HomeMy WebLinkAbout2001-04-09 City Council (13)City of Pal. Alto
City Manager’s Report
TO:HONORABLE CITY COUNCIL
2
FROM:
DATE:
SUBJECT:
CITY MANAGER
APRIL 9, 2001
DEPARTMENT:PLANNING AND
COMMUNITY ENVIRONMENT
CMR: 187:01
PROPOSED NEIGHBORHOOD TRAFFIC CALMING PROGRAM
RECOMMENDATION
Staff recommends that the City Council:
Adopt the City of Pal. Alto Neighborhood Traffic Calming Program (NTCP), as
amended by the Planning and Transportation Commission. and the Policy and
Services Committee, including the designation of the City Manager as the approving
authority for trial installation of spot treatment traffic calming projects on local
streets using any traffic calming measures except street closures, diverters, or other
measures that substantially divert traffic to other streets.
Refer to the Finance Committee consideration of increased funding for spot treatment
traffic calming projects, beyond the allocated $100,000 annual budget.
Refer to the Finance Committee the following issues regarding neighborhood traffic
calming studies, as a prerequisite toincluslon of such studies in the NTCP:
(a)
(b)
Consider funding options for neighborhood traffic calming studies, which are
funded by the $100,000’ annual budget for spot treatment traffic calming
projects;
Include education and enforcement in addition to engineering solutions for
neighborhood traffic calming studies, with consideration of the funding
implications thereof; and
(c)Design neighborhood traffic calming projects with attention to the importance
of aesthetic impact, with design of traffic calming measures by a landscape
architect, and with consideration of the funding implications thereof.
DISCUSSION
On March 1, 2001, the Council Policy and Services Committee reviewed the proposed
NTCP. The Committee recommended that City Council approvethe spot treatment program
on¯ the consent calendar, with the following changes:
CMR:187:01 Page 1 of 4
(a)
(b)
(c)
Include education and enforcement in addition to engineering solutions as part of a
comprehensive program for traffic calming;
Design traffic calming projects with attention to the importance of aesthetic impact,
with design of traffic calming measures by a landscape architect; and
Request that the Finance Committee consider an increase in the existing $100,000
annual fimding amount, as this amountis not sufficient to meet the community
expectation that approval of the NTCP will engender, nor to design projects in an
aesthetically pleasing manner.
The Committee approved inclusion of neighborhood studies in concept only, with a
recommendation to forward this aspect of the NTCP to the Finance Committee for further
discussion and recommendations. The Policy and Services Committee recommends that the
Finance Committee consider the following issues pertaining to the traffic calming program
for entire neighborhoods:
(d)
(e)
(0
Consider funding options for neighborhood studies, which are currently not funded
by the $100,000 annual spot treatment traffic calming budget, as well as increased
funding for the spot treatment projects;
Include education and enforcement in addition to engineering solutions for traffic
calming (and the resource implications thereof); and
Design traffic calming projects with attention to the importance of aesthetic impact,
with design of traffic calming measures by a landscape architect (and the resource
implications thereof).
Spot Treatment Program
Staff has modified the defmition of traffic calming and associated language in the NTCP to
allow for education and enforcement as part of traffic calming projects (see revised
def’mition under "Project Description" above). A few cities conduct their traffic calming "
programs with education and enforcement as a required first phase of a traffic calming
project, including before and after data-analysis, before any engineering measures can be
considered. Staff would not propose this approach. Most Palo Alto residents interested in
traffic calming feel that the impacts of education and enforcement, while potentially
effective in the short run, fade over time as these resources are moved to other locations.
Furthermore, education and enforcement by themselves are not effective in reducing the
volume of cut-through commute traffic, which is a common problem for which residents
request traffic calming. Therefore, staff proposes to use enforcement and education
primarily in combination with physical traffic calming measures. The sole use of education
and enforcement would be most appropriate when a traffic calming request does not meet
the minimum criteria to qualify for physical measures, or when a qualified request faces a
long wait for.physical measures due to insufficient funding or staff’mg.
CMR:187:01 Page 2 of 4
With regard to aesthetics, staff anticipates proposing only higher-quality designs, as
explained on page 10 and Attachment 4 of the September 27, 2000 Transportation Division
staff report to the Planning and Transportation Commission. The Policy and Services
Committee desires that only high quality designs be considered, with design by a landscape
architect. Therefore, for traffic calming designs that staff contracts out (which should be the
norm), staff will contract with a .landscape architectural f’mxi as the lead for the project. For
any projects that are designed in-house, staff will work with the City’s town architect for
review and approval of the design. Once an acceptable design for a measure has been
developed (a gateway, for example), staff would anticipate using the same or a similar
design for future installations of the same measure, with only a brief review by the .town
architect. One commonly-used traffic calming measure, the:~Speed hump, does not have any
architectural or landscape elements, and is considered by many. residents to be unattractive.
This results in some degree of self-elimination of this measure when residents decide not to
request speed humps for aesthetic reasons. Staffwill review the standard speed hump design
to seeif any of the signing or striping elements (the most unsightly aspects of speed hump
projects) could be eliminated or reduced in size.
Neighborhood Studies
Staff has modified the NTCP to remove neighborhood studies from the program, pending
further discussion by the Finance Committee.
The NTCP (Attachment A) includes all of the above amendments requested by the Policy
and Services Committee, as well as the amendments previously made by the Planning and
Transportation Commission and staff.
POLICY IMPLICATIONS
A full discussion of policy implications-is contained in pages 21 - 23 of the September 27,
2000 Transportation Division staff report to the Planning and Transportation Commission,
and on pages 7 - 8 of CMR:105:01 of January 16, 2001.
TIMELINE
Staff will agendize those issues referred by the Council to the Finance Committee.
ATTACHMENT
A. City .ofPalo Alto Neighborhood Traffic Calming Program (revised April 9, 2001)
CMR:187:01 Page 3 of 4
PREPARED BY: Carl Stoffel, Transportation Engineer ¯
DEPARTMENT HEAD:
G. EDWARD GAWF
Director of Planning and
Community Environment
Assistant City Manager
cc:NTCP Workshop Attendees
CMR: 187:01 Page 4 of 4
A’n’ACHMENT A
Neighborhood
, Oii\c Ca ming Progro/b
Draft
City of Palo Alto
Department of Planning and Community Environment
Transportation Division
April 9, 2001
CITY OF PALO ALTO
NEIGHBORHOOD TRAFFIC CALMING PROGRAM
TABLE. OF CONTENTS
INTRODUCTION ....................2
II.OBJECTIVES 5
II1.GUIDELINES ..................... .. 8
IV.PHYSICAL TRAFFIC CALMING MEASURES .....11
V.PROS AND CONS OF TRAFFIC CALMING .......13
VI.PROCEDURE FOR REQUESTING TRAFFIC
CALMING MEASURES ..................17
VII.
VIII
NEIGHBORHOOD TRAFFIC CALMING REQUESTm
MINIMUM QUALIFYING AND RANKING CRITERIA . .23
REMOVAL OF TRAFFIC CALMING MEASURES. ..25
Traffic Calming Program
Page 1 DRAFT
April9,2001
PATCP. 12
CITY OF PALO ALTO
NEIGHBORHOOD TRAFFIC CALMING PROGRAM
for Local and Collector Streets
INTRODUCTION
The City receives numerous requests, complaints, and suggestions from residents about traffic
issues--pertaining to maintenance, stop signs, visibility impairment, parking, traffic signal timing,
lane striping, speeding, traffic volumes, trucks, crashes, and others. City staff responds in several
ways to these requests. For example, routine maintenance of streets, signing, signals and
landscaping is handled by the Public Works and Utilities Departments. Violations of speed limits
and other rules of the road are handled by the Police Department. Stop sign requests are evaluated
by the Transportation Division and require City Council approval. Specific operational issues--for
example, a parking problemor a traffic lane configuration problem are routinely investigated by the
Transportation Division. The Transportation Division also manages the Residential Arterial Traffic
Calming Program, as discussed on the next page. The Transportation Division and the Police
Department often address student~ safety and transportation issues by undertaking special school-
related studies. The Transportation Division is also active in several organizations dealing with
traffic concerns at the regional level.
Somewhat different than the above traffic issues are the concems of some residents about chronic
problems affecting local residential streets--speeding, commuter shortcutting, or just too much
traffic--affecting areas ranging from a single block to an entire neighborhood. Addressing these
problems poses a challenge because they are not easily addressed by the usual City actions described
above. For. example, the degree of speeding is often not severe or frequent enough to warrant taking
Police Department time away from other problem areas, Commuter shortcutting is not a traffic
violation that can be addressed by enforcement. Educational techniques that are provided by the
Police Department or Transportation Division can help address these issues to some degree, but
require continual effort. Often, the City has addressed such neighborhood traffic problems only
when the issues were pervasive enoughto affect an entire neighborhood. The result is a sometimes
uncertain procedure or a neighborhood-wide traffic study that requires considerable City Council
involvement. The Neighborhood Traffic Calming Program (NTCP) makes it easier for the City to
respond efficiently and fairly to neighborhood traffic problems by:
establishing a defined formal procedure for evaluating requests for "spot" treatments
affecting one or a few streets without causing noticeable spillover traffic onto other
residential streets; and
¯providing a dedicated funding source for these "spot" treatments.
Traffic Calming Program
Page 2 DRAFT
April 9, 2001
PATCP. 12
For purposes of this program, traffic calming is defined as the combination of physical, educational,
and enforcement measures that reduce the negative effects of motor vehicle use, alter driver
behavior, improve safety for non-motorized street users, and improve neighborhood livability.
Physical measures include devices such as speed humps and traffic circles, and are discussed in more
detail in Chapter IV. The Neighborhood Traffic .Calming Program unifies and formalizes existing
City policies and programs relating to protection of neighborhood streets from impacts of vehicular
traffic. The City Council has established an annual budget of $100,000 (subject to periodic renewal)
in order to fund the design and installation of simple traffic calming measures under this program.
Some expensive projects, such as multiple fully landscaped circles and islands, will require a
separate funding allocation from the City Council. Projects involving an entire neighborhood will
not be prioritized or acted upon as part of this program. They will require special approval and
funding from the City Council before they can be undertaken. T, he Transporlation Division
manages the overall program, including design, construction, and appropriate educational activities.
The Police Department provides enforcement and, where appropriate, safety and educational
outreach. The Public Works Operations Division is responsible for maintenance. Figure 1 illustrates
how the traffic calming program fits in with the other ways the City addresses traffic issues.
The traffic calming program described here is only for residential local and collector streets. Figure.
2 shows which streets are local, collector and arterial streets. Local and collector streets must be
predominantly residential in character in order to qualify for the traffic calming program (i.e.,
having at least 50 percent of street frontage in single or multiple family uses). Traffic issues related
to arterial streets are quite different from those of local and collector streets, as the purpose of
arterial streets is to carry larger volumes of through traffic in a relatively free-flowing manner. In
fact, many of the problems that residents experience on local and collector streets result from
congested traffic conditions on arterial streets. This Neighborhood Traffic Calming Program does
not address arterial street issues, except that a traffic calming project might include traffic flow
improvements on a nearby arterial street that are designed to attract shortcutting traffic out of a
neighborhood and back onto an arterial. Indeed, reducing traffic problems on local and collector
streets depends partly on maintaining free-flowing arterial traffic. Changes to arterial streets that
impede free traffic flow make traffic calming on nearby local and collector streets more challenging.
Recognizing the interest in, and need for;. traffic calming on arterial streets that are residential in
nature, the City has already embarked on a multi-year project that will implement physical changes
to residential arterial roadways. The primary goal of the Residential Arterial Traffic Calming
Program is to reduce speeds on residential arterial streets while maintaining full arterial traffic
volumes and full access for all vehicles and other road users. This is a distinct program from the
Neighborhood Traffic Calming Program described here and is being .implemented on a separate
track.
The City intends to apply the guidelines and procedures of the Neighborhood Traffic Calming
Program in a flexible manner. This program should be viewed as a "living document" that will be
modified frequently as the City. gains experience with the various aspects of the program, such as
the minimum qualifying criteria, ranking system, and/or procedures. Every effort has been made
to streamline this program, while still including the important elements of citizen participation and
Traffic Calming Program April 9, 2001
Page3 D [~ A[l I PATCP.12
involvement of the Planning and Transportation Commission and City Council in the most
important decisions.
Traffic Calming Program
Page 4 DRAFT
April 9, 2001
PATCP.12
II.OBJECTIVES
The following objectives have been established for the Neighborhood Traffic Calming Program.
Improve pedestrian and bicycle safety and neighborhood livability by reducing traffic
speeds, crashes, and cut-through traffic on local and collector streets, by means of
engineering, education, and enforcement measures.
Establish a defined formal procedure to implemeilt traffic calming measures in an
efficient, fair, and timely manner in response to residents concerns.
Provide an annual budget for "spot treatment" traffic calming projects (i.e. projects of
one or a few streets, with no noticeable traffic shift onto other residential streets).
Focus Planning and Transportation Commission and City Council involvement on the
major decisions required to implement traffic calming projects.
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Page 5 DRAFT
April 9, 2001
PATCP. 12
cal & Collector Streets
Figure 1: Types of Traffic/Transportation Issues
LOUI,
F_.Y~ P I~__~ WAy
F P, F- F_.WAY
FIGURE 2 [DRAFT)
III. GUIDELINES
The following guidelines are observed in the Neighborhood Traffic Calming Program.
1.Traffic not generated by or related to a specific neighborhood should be encouraged to use
arterial streets.
A low ambient level of non-neighborhood traffic on local streets usually exists and is
virtually unavoidable (estimated at approximately 10-20 percent of total daily volume).
Preservation of emergency vehicle access will be maintained in traffic calming projects.
Reasonable automobile access to traffic calmed streets should be maintained. Pedestrian,
bicycle, and transit access should be encouraged and enhanced wherever possible. The
policy of the Comprehensive Plan is to keep all neighborhood streets open unless there is a
demonstrated safety or overwhelming through traffic problem and there are no acceptable
alternatives, or unless a closure would increase the use of alternative transportation modes.
Lanes may need to be narrowed at specific locations in order to accomplish traffic calming,
thus lessening the shared space available for bicyclists and drivers. The resulting vehicle
speeds and volumes will determine the extent to which bicyclists feel negatively affected.
Any localized impacts on bicyclists must be balanced with the overall benefit to bicyclists
and neighborhood residents of lower vehicle speeds and/or lower traffic volumes attained
through traffic calming.
Removal of parking spaces may be necessary in order to provide sufficient room to
install some traffic calming measures. Parking removal authorized by City staff will not
exceed 60 feet on side of a local street, within every 400-foot length of street (excluding
intersecting public or private streets or alleys). Parking loss at specific locations must be
balanced with a neighborhood’s desire to realize the benefits of the traffic calming
measures.
The traffic calming program is limited to local and collector streets that are primarily
residential in nature. As defined in the Comprehensive Plan, local streets are designed to
provide access to adjacent properties only, while collector streets perform not only that
function, but also distribute traffic within an area to and from arterials. This program does
not apply to non-residential streets nor to any arterial street (refer to Figure 2).
Traffic Calming Program
Page 8 DR.AFT
April 9, 2001
PATCP. 12
10.
11.
12.
13.
Traffic calming measures on a local street will be designed to minimize the diversion of
traffic to another adjacent local street. However, some diversion may be unavoidable. An
increase of up to 25 percent of existing volume on an adjacent local street is considered to
be acceptable on most streets, as volume changes up to that magnitude are not perceived by
most residents. One exception is that the resulting total traffic volume on an adjacent local
street (existing volume plus the added volume diverted from the. traffic calmed street) should
not exceed 2500 vpd.1
Traffic calming measures on a collector street will be designed to address primarily speed.
As noted above, collector streets are designed to serve some level of neighborhood-related
through traffic to/from arterials. In some cases, diversion 0ftraffic from a local to a collector
street may be appropriate, depending in each specific case on the nature and amount of the
diverted traffic, up to an increase of 25 percent of existing volume.
In the hierarchy of city streets, arterials are the designated and desirable carriers of through
traffic and, as such,, will often receive non-neighborhood through traffic diverted from local
and collector streets by neighborhood traffic calming measures.
Traffic calming projects to be undertaken in this program may range from a single block
to multiple streets, but not an entire neighborhood. Neighborhood traffic calming studies,
and any unusually expensive or complex traffic calming projects will be conducted and
funded separately after specific authorization of the Planning and Transportation
Commission or City Council.
The procedures established for this program will ensure that requests for traffic calming
¯ are treated fairly in that they must meet certain minimum criteria to be considered for
study, and will be prioritized according to stated criteria. Exceptions to the normal
prioritizing procedure would usually be considered only as .a consequence of (a)
unanticipated impacts of new development or redevelopment; (b) unanticipated impacts
of changes in the City’s street network; (c) unanticipated impacts of other traffic calming
projects in the City; o.r (d) appearance of unusual safety problems on a street or in a
neighborhood. In one or more of these instances, Transportation may forward a revised
list of rankings for review by the Planning and Transportation Commission and approval
of City Council.
The number of traffic calming projects may exceed the available level of funds and staff.
1The 25 percent increase is based on the Traffic Infusion on Residential Environments (TIRE) index that shows
that, up to this point, most residents do not perceive the increase in volume. The TIRE index is a method of describing and
measuring residents’ perceptions of the effect of street traffic on residential activities such as walking, cycling, playing,
interacting with neighbors, and backing a car in and out of a driveway. The index was developed by neighborhood traffic
management researchers in the United States and England, and serves as a reference tool for judging the anticipated effect
of changes in traffic volumes. The City has employed this index in prior neighborhood studies, in evaluating traffic impacts
of land development projects, and in the Environmental Impact Report for the Comprehensive Plan.
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April 9, 2001
PATCP. 12
14.
This may result in delw,,~ of from one to three years for consideration of some requests,
or the inability to address these requests..
If a trial traffic calming plan results in traffic diversion to adjacent streets that exceeds
the allowable 25 percent threshold, causes unacceptable delays to the emergency
services, or has other unintended results as determined by City staff,the trial will be
terminated, even if residents are in favor of the plan.
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April 9, 2001
PATCP. 12
IV. PHYSICAL TRAFFIC CALMING MEASURES
Typical physical traffic calming measures are listed below and are illustrated and described in
the Appendix. They are listed generally in order of increasing effectiveness in reducing traffic
volumes and/or speeds.
Warning and Specialty Signs
Stop Signs [technically not a traffic calming device but may be used in traffic calming plans]
Speed Limit Signs
Gateways
Textured Crosswalks.
Special Striping, Narrow Lanes
On-Street Parking
Bulbouts, Chokers, Curb Extensions
Median Island Slow Points
Raised Intersections**
Traffic Circles
Serpentine Streets, Chicanes*
Speed Tables and Raised Crosswalks**
Speed Humps*
Slow Streets*
Turn Prohibition Signs
Diagonal Diverters, Forced Turn Channelization, Median Barriers*
One-Way (Half) Street Closure*
Full Street Closure*
*Not permitted on collector streets unless an exception is granted by the Fire
Department and/or the Transportation Division. All speed hump projects will be
reviewed by the Fire Department before approval is given.
**Permitted on collector streets at intersections after Fire Department review. Speed
tables and raised crosswalks may be permitted on collector streets midblock if Fire
Department approves the specific location.
These measures can be used individually or in combination. Not all of them may be feasible or
acceptable in all locations. For example, street closures, though very effective at reducing non-
neighborhood traffic, are usually very controversial, disrupt the traditional neighborhood street grid,
can limit emergency vehicle access, and may shift too much traffic to adjacent local streets.
Comprehensive Plan Policy T-33 discourages street closures except for certain situations, such as
an overwhelming through traffic problem with no alternative measures available, and/or if closures
would increase the use of alternative transportation modes. Traffic calming options are much more
limited on collector streets, as collectors are the designated carriers of neighborhood traffic to and
from arterials, as well as part of the Fire Department’s primary emergency response network. Speed
humps, while very effective at reducing speeds without prohibiting access, have a substantial
Traffic Calming Program April 9, 2001
Page 11 D [~ A [: ]"PATCP.12
negative impact on fire and paramedic services. Therefore, they cannot be used on collector streets
unless the Fire Department and the Transportation Division grant an exception. More discussion on
the limitations imposed on the use of traffic calming measures is contained in the next chapter of
this program.
Some measures, such as bulbouts and medians, could be installed inexpensively with painted
striping or raised pavement markers instead of constructing raised islands. This is not
recommended, because experience has shown that drivers often drive over painted stripes and
markers, thus reducing the effectiveness of the device. Similarly, the use of signs is not as effective
as actual physical devices on the pavement because drivers may ignore the signs, and regular police
enforcement is usually requiredl Traffic calming can also be accomplished to somedxgree bythe
presence of on-street parking, which narrows the traveled way. Another effective, but expensive,
engineering method of reducing speed is the complete re-engineering of an entire street corridor in
order to create a narrower crossection, and/or to "’close in" the street environment with extensive
landscaping, on-street parking, or other infrastructure.
The detailed procedures and minimum qualifying criteria by which residents can obtain traffic
calming measures are described in Chapters VI and VII later in this document.
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April 9, 2001
PATCP. 12
V. PROS AND CONS OF TRAFFIC CALMING
Traffic calming projects have successfully reduced speeds and volumes in a variety of situations.
Most cities, including Palo Alto, have numerous physical traffic calming measures already
employed, and more are constantly being installed. Physical traffic calming programs are popular
among residents, resulting in a high demand for projects. Generally, the benefits of traffic calming
are obvious and predictable, while the disadvantages may not be quffe so obvious. If not
implemented correctly, traffic calming measures could result in problems more significant than the
original concern. The following discussion is provided so that residents can be fully informed before
¯ they request action, and so they understand the issues that the City must consider in implementing
a traffic calming project.
The Benqfits o.fTra.ffic Calming Measures. Speeding is one of the primary complaints that the City
receives about traffic conditions on local streets. The most effective speed control measures are
those that force drivers into vertical or horizontal movement. These are speed humps, speed tables,
raised crosswalks and intersections, traffic circles, median slow pointh, and serpentine streets. These
measures generally reduce vehicle speeds to 15 mph at the device, and to 25 - 30 mph along a
corridor of multiple devices, depending on their spacing. Reduced speeds result in lower noise
levels; reduced severity of crashes; improved neighborhood environment for bicycling, walking and
residential activities. Non-neighborhood traffic can be reduced by approximately 10 - 20 percent
by a series of speed reduction measures, and can be dramatically reduced (up to 100 percent) by
street closures and diverters. The benefits of reduced traffic volumes are similar to those of reduced
speeds. Reducing the level of non-neighborhood traffic may also reduce littering and crime. Many
measures provide opportunities for landscaping in formerly paved areas, thus contributing positively
to neighborhood aesthetics. There is some evidence that a well-designed traffic calming project can
increase neighborhood property values.
One of the most important impacts of traffic calming is the potential reduction in the severity and
number of crashes on traffic calmed streets. Safety is enhanced through increased driver awareness
of other street users and through reductions in volumes, speeds and conflicts. In the United States,
reduction of crashes due to installation of traffic calming measures has been reported to be an
average overall of 50 percent. Traffic circles appear to offer the greatest reduction in collisions.
Speed.reduction is especially important for pedestrian safety, as the severity of injury to a pedestrian
when hit by an automobile is dramatically reduced by lowering of vehicle speeds from 35 mph
(usually fatal) to fewer than 20 mph (usually just minor injuries). The value of such safety
enhancements can partially offset the negative impacts of some traffic calming measures on
emergency vehicle access.
Delays to Emergency Response Vehicles. Some traffic calming measures can cause substantial delay
to fire and paramedic vehicles and ambulances. These vehicles are particularly susceptible to the
vertical displacement of speed humps because of the weight and length of fire trucks, and the
delicate instruments and patients in paramedic vans and ambulances. Creating bumps, dips and
curves is precisely the result being sought in many traffic calming measures. While these maneuvers
will cause moderate discomfort and delay for normal passenger vehicles, including those used by
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April9,2001
PATCP. 12
the Police Department, they cause a much greater problemfor fire and paramedic vehicles. These
vehicles must come to_almost a complete stop before passing over a speed hump. Measures that
create horizontal displ~ement, such as traffic circles, serpentine streets, or median slow points, also
delay emergency vehicles, but less than humps. Traffic calming measures that are placed at
intersections, such as traffic circles, raised crosswalks, and raised intersections, are less of a problem
for the emergency services, because drivers of emergency vehicles must slow down at intersections
anyway. Delays caused by traffic calming measures must be considered by the emergency services
as they strive to meet the adopted mission goals of response times of four minutes or less for 90
percent of fire and basic medical calls, .and six minutes or less for 90 percent of advanced medical
(paramedic) calls. For example, each speed hump creates a delay of up to ten seconds for a ladder
truck and up to five seconds for an ambulance. Speed humps are usually installed in sets of two to
three humps per block, so potential delay can accrue quickly in a multi-block speed hump project.
For the purpose of this traffic calming program, the Fire Department has designated the City’s
network of expressways and arterial and collector streets as the primary fire response network
(illustrated in Figure 2). The Department may also designate certain local streets as routine
emergency routes, especiallyif they are in the immediate vicinity of a fire station. Because collector.
streets are eligible for this traffic calming program, yet are part of the emergency response network,
traffic calming measures for collector streets must be specifically designed to have minimal impact
on emergency vehicle access times. The traffic calming measures designated with an asterisk (.*) in
Chapter IV usually cannot be used on collector streets, in part, because of emergency vehicle
response impacts. The Fire Department emphasizes that all City streets, including local streets,
should be available for possible response routes in emergencies. On the other hand, the Department
understands that a reasonable number of traffic calming measures should be permitted on local
streets due to residents concerns about impacts of automobile traffic on their neighborhoods. It
should be expected, however, that the Fire Department would resist most speed hump projects, and
instead advocate for other types of traffic calming measures. All requests for speed humps, whether
on local or collector streets, will be reviewed by the Fire Department .before approval is given. Due
to impacts on the emergency services, speed hump installations will be limited to a maximum of 50
percent of the traffic calming capital budget for each fiscal year.
. Traffic calming measures will typically reduce the severity of automobile crashes, thus reducing the
number of calls for service in the traffic calmed area. But the Fire Department also responds to fires,
medical emergencies, and domestic accidents that, collectively, represent the majority of calls on
local neighborhood streets. In the final analysis, there must be a balance between the speed of
emergency vehicle response versus the neighborhood quality of life improvements that result from
traffic calming. The City and residents must keep this balance in .mind in considering the
implementation of traffic calming measures.
Solving the Problem or Shifting the Problem? A traffic calming project must be carefully designed
and monitored to minimize shifting traffic from one neighborhood street to another. The drivers
most likely to change routes are those who are not residents of the street on which the traffic
calming measures are installed. Any traffic calming device that effectively reduces speeds can be
expected to divert s ome portion of traffic to other routes (10 - 20 percent for a series of speed humps
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and traffic circles), even though the street remains open. This is because, for most drivers, time is
the primary factor in route choice. A 50 - 90 percent reduction in traffic volume can be obtained
with full and partial street closures, with that level of traffic moving to other streets and corridors.
This high level of diverted traffic is diffict~lt to control and can be a problem if it moves to adjacent
local neighborhood streets.
Ideally, drivers diverted by traffic calming measures should move to a nearby arterial route if it is
not too overcrowded. Other drivers who are closer to their origins or destinations might properly
shift to neighborhood collector streets. Sometimes drivers shift to other routes that are in entirely.
different corridors from the original route. Unfortunately, not all diverted drivers will shift to a
"proper" route and may end up on another local residential street. The City endeavors to design
traffic calming installations that minimize this "shifting of the problem" to other local streets. A
good traffic calming design will minimize the volume of diverted traffic, and/or control to which
streets the diverted traffic moves. This traffic calming program is based on a permissible shift of
traffic that amounts to an increase of up to 25 percent of the volume on the street to which the shift
occurs. This increase is based on traffic research that shows that, up to this point, most residents do
not perceive the increase in volume (refer to Guideline 8). Traffic calming measures are effective
in reducing speeds in the immediate vicinity of the measures. In order to reduce speeds along a
corridor, an effective traffic calming project will usually require a series of measures. Drivers may
"make up" lost time by speedingup between widely spaced measures or after a series of measures.
Everyone Is Inconvenienced. Enforcement and education efforts aimed at controlling speeds or
influencing driver behavior impact primarily the irresponsible drivers--usually a relatively small
percentage of the driving population. On the other hand, physical traffic calming measures create
delay and inconvenience for all drivers using the particular street.
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Impacts on Parking and Other Road Users. Bicyclists, pedestrians and any other road users can
encounter problems with physical traffic calming measures. All measures are designed to be
acceptably safe for all users, assuming that these users are attentive as they proceed down the street.
Speed humps and traffic circles, for example, are two of the most popular traffic calming measures.
Bicyclists can traverse speed humps at typical cycling speeds without slowing down, However, if
a bicyclist is careless (e.g., riding with no hands, not watching the road, no lights at night, etc.), the
cyclist might unexpectedly encounter a hump and be caught off balance. Where lanes are narrowed,
bicyclists and drivers usually must share the lane, po.ssibly becoming a problem if traffic volumes
are moderate to high. Traffic circles force drivers to the right at intersections, toward (but not into)
the crosswalks, and pedestrians sometimes feel that their safety is being compromised. Residents
who are used to parking in front of their homes in the street may be impacted also, as some measures
require prohibition of on-street parking. These disadvantages for various user groups need to be
considered along with the recognized benefits of overall traffic speed and volume reduction in the
area that results from a traffic calming project.
Visual Concerns. While some traffic calming measures can be visually pleasing by introducing
landscaping into formerly paved areas, Others can be unsightly. Since these measures are intended
to pose obstacles to drivers, they must be well signed, striped and reflectorized in order to avoid
safety problems and limit potential liability exposure for the City. For example, a traffic circle offers
the visual benefit of providing a large new area of landscaping in a former expanse of asphalt.
However, this visual benefit is partially offset by the addition of several new poles with highly
visible reflective signs. Speed humps offer only increased visual clutter, with highly visible traffic
signing, reflective markers and signs. Negative visual impacts are multiplied when a street with a
series of measures is viewed from one end of the traffic calmed area. This visual consideration
should be part of residents decision-making process in requesting traffic calming measures.
Costs: Most well-designed traffic calming measures are expensive.. Administration of the traffic
calming program and the design, installation, maintenance and enforcement of traffic calming
measures create recurring costs to the City. The annual cost of the "spot treatment" element of the
Neighborhood Traffic Calming Program is $100,000, not including administration, enforcement,
maintenance, neighborhood studies, or unusually expensive traffic calming measures. Ultimately,
all these costs are borne by Palo Alto taxpayers.
The City has considered the general balance of the above, pros and cons and, by its adoption of this
traffic calming program, concludes that the benefits of traffic calming outweigh the disadvantages.
This process must then be repeated by the City and residents for each specific traffic calming
project. The purpose of the guidelines and criteria that govern this program is to insure, to the
greatest degree possible, that traffic calming measures are used where there is a reasonably high
probability that the benefits will outweigh the disadvantages.
Traffic Calming Program
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PATCP. 12
VI. PROCEDURE FOR REQUESTING TRAFFIC CALMING MEASURES
When a request for.traffic calming is received, the Transportation Division first determines whether
the request could be handled through other simpler procedures described, in the Introduction. For
example, a problem of drivers speeding around a sharp curve might be solved simply by installing.
appropriate signs or striping at that specific location. The City will make every effort to mitigate the
identified problem(s) at this early stage without having to embark on an actual traffic calming
project.
Many steps in this procedure will not be necessaryfor simple traffic calming projects--such as speed
humps. Once a traffic calming project has begun, the Transportation Division will determine which
steps in the procedure would apply to that project and will guide residents accordingly. If the City
determines that a project would be too large for the budget of this traffic calming program, or
would/shouldinclude an entire neighborhood, the project will be considered as a "complex project"
or "neighborhood project". Due to the usual high capital expense and staffing needs associated with
such projects, they will be placed on a separate project list to be forwarded annually to the City
Council for separate funding and authorization to proceed. When such projects are started, they
would usually be conducted following the same procedure as for other traffic calming projects, as
follows.
Receive request and determine eligibility and ranking.
A request for traffic calming on one or a few streets must include a petition signed by 25
percent of the households on each block where action is requested. A household is defined
as any owned or rented living unit with its own street address, regardless of how mariy people
live in the unit. Each household is represented by one signature, regardless of the number of
people in the household. The street(s) for which traffic calming is requested must have at
least 50 percent of the ~otal street frontage developed in, or zoned or, single or multiple
family land uses.
A traffic calming request may pertain toproblems of speedingl through traffic, or crashes on
local or collector streets. Upon receipt of a traffic calming request, the Transportation
Division collects the data required to determine if the minimum qualifying criteria described
in Chapter VII are met. Qualified requests are then placed on the project list according to the
ranking criteria in Chapter VII. If the minimum criteria are not met and, if the problem can
be addressed through police enforcement, education, or other means, the City will take the
best corrective action. Transportation staff will begin work on traffic calming projects
according to the project’s position in the project list and the staffing available. Other possibl.e
exceptions to the standard criteria are discussed in Chapter VII.
Traffic Calming Program
Page 17 DRAFT
April 9, 2001
PATCP. 12
2.Determine project area and notify residents.
Once Transportation is ready o work on a traffic calming request, the staff first determines
the "primary~ street" segment(s) where traffic calming measures might be placed. Primary
street segments are usually bounded by collectors, arterials or other through streets.
Transportation also determines whether any cross streets or adjacent parallel streets might be
affected by traffic calming actions that might be taken on the primary street(s). This larger
area, consisting of the primary streets, cross streets and/or adjacent parallel streets, is termed
the "project area." A letter is then sent to all households within the project area to notify
residents that a project is beginning, to share the data gathered so far, and to~.~ if there are
other traffic issues that should be addressed. Transportation staff can add any new primary
streets or segments to the project, based on the feedback obtained from this outreach.
Hold first project area meeting.
Residents of the prgject area are notified of the first Project area meeting, the purpose of
which is to introduce the project and to identify any other traffic issues that should be
addressed. The impacts of various traffic calming measures on the provision of emergency
services will be specifically discussed. Volunteers are solicited to form aworking groupthat
will meet separately to begin development of one or more traffic calming plans to address
issues on the primary streets. If the traffic calming project is simple (e.g., involves only one
street), Transportation staff will develop one or more traffic calming plans for presentation
at this first meeting. For such simple cases, agreement on a traffic calming plan might be
reached at this meeting. Any potential plan involving the use of vertical traffic calming
measures (speed humps, speed tables, raised crosswalks, raised intersections) will take into
consideration the needs of any person living in the project area who has a disability as defined
in the Americans with Disabilities. Act (ADA). 2
Gather additional data and hold working group meetings.
Additional data, possibly including a license plate survey to determine the extent of non-
neighborhood through traffic, may need to be gathered at this point, depending on what other
issues were raised in the initial interest survey. One or more working group meetings are
2 A situation could arise in which a person with a disability protected by the ADA would be denied ingress or
egress to the person’s place of residence because of the impact of driving over such a device. That person should be able to
reasonably demonstrate that the proposed measure.would aggravate tile protected disability. In that situation, any traffic
calming plan under consideration that included any of the above vertical measures would need to be modified to provide
an unobstructed route of ingress and egress to the person’s residence.
Traffic Calming Program
Page 18 DRAFT
April 9, 2001
PATCP. 12
convened to refine Transportation Division’s original plans and/or develop ideas for new
plans. The working group continues to meet until agreement is reached on a preferred plan
and one or more alternates.
Mail plans to residents and hold second project area meeting.
~The preferred plan and alternate(s), including projected traffic data developed by
Transportation staff, are mailed to project area residents along, with announcement of a
meeting. Residents are asked to mail comments back to the City and/or attend the meeting.
The plans are presented to residents at the meeting. Transportation will attempt to include any
modifications desired by residents. It is desirable for project area residents to reach consensus
on the preferred plan by this point.
Conduct survey to determine if a trial should be implemented.
The Transportation Division prepares a survey for residents that describes the traffic calming
measures proposed to be placed on the primary street(s) and asks if they would support
undertaking a four-month trial (six months for complex projects). How the survey is
conducted is determined by the type of traffic calming project. Because some traffic calming
projects will not fit neatly into the following categories, Transportation might need to vary
the survey procedure to best fit special cases.
(i)For spot treatment local street projects that do not include street closures, diverters,
or other measures that might substantially divert traffic to other streets, only those
households located on the primary street(s) will participate in the survey. If measures
are proposed for intersections (e.g., traffic circles), households on the intersecting
street up to one block in either direction will also be surveyed. One response is
allowed per household, regardless of the number of people in the household. Non-
resident property owners and households on other project area streets will not
participate in the survey at this time. In order for a trial to be considered for approval,
a simple majority (50+ percent) of all households on the primary street(s) (i.e., not
just of survey responses) must indicate support for the trial. If alternative plans are
included in the survey, the total support for all plans must be a simple majority, and
the alternative with the most support will be considered for a trial. Based on the
survey results, the City Manager will decide if a trial can proceed. The Transportation
Division prepares a study of potential project impacts. Neither Planning and
Transportation Commission nor City Council approval for a trial is required for these
projects, so the procedure skips to Step 8.
(ii) For collector street projects, complex projects, and projects including street closures
Traffic Calming Program
Page 19 DRAFI
April 9, 2001
PATCP. 12
m
or diverters, all project area households will be eligible to participate in the survey
(i.e., residents of the primary street(s) plus any adjacent street(s) affected by traffic
diversion). One response is allowed per household: Non-resident property owners will
not participate in the survey at this time. A simple majority (50+ percent) of survey
responses must indicate support for the trial. If alternative plans are included in the
survey, the total support for all plans must be a simple majority, and the alternative
with the most support will be recommended to. proceed to a trial. The
recommendation of the Planning and Transportation Commission and the approval
of the Director of Planning and Community Environment are required for the trial to
proceed.
If the required resident support described above is not obtained, the procedure may either
return to Step 4 (working group meeting) to select another alternative and repeat the above
procedure, or the process ends at this point.
Planning and Transportation Commission review and Director of Planning
and Community Environment approval to conduct a trial plan of collector
street projects, complex projects, and projects including street closures or
diverters.
The Transportation Division prepares a report to the Planning and Transportation
Commission in order to request its review of a trial of the traffic calming plan (including
selection of the preferred alternative for the trial, if necessary). The entire project area is
notified of the meeting. The Commission listens to public testimony and discusses the
proposed trial. The recommendations of the Commission are then forwarded to the Director
Of Planning and Community Environment for final approval. If the trial is not approved, the
procedure may either return to Step 4 (working group meeting) to select another alternative
and repeat the above procedure, or the process will end at this point.
Design, implement and conduct approved trial.
The detailed plan for the trial is designed and bids are solicited for construction. The design
effort may need to be contracted out, in which case bids would also need to be solicited for
the design work. Traffic data is gathered before the trial is implemented, and at or near the
end of the trial. The typical trial period will be four months for spot treatment pr.ojects and
six months for complex projects.
Evaluate trial results and hold third project area meeting.
At or near the end of the trial, City staff evaluates the results of the trial plan. Residents of
Traffic Calming Program
Page 20 DRAFT
April 9, 2001
PATCP. 12
the entire project area are notified by mail of the trial results. An optional third project area
meeting may be held at which the results of the trial are discussed. At any point during a trial
or at the end, Transportation could determine that the trial was clearly having substantial
unacceptable impacts and should be removed, as discussed in Chapter VIII.
10.Conduct survey of residents regarding results of trial.
11.
Transportation distributes a survey to determine if residents believe that the trial was
successful and if the project should be considered for permanent installation. The survey area
includes residents and property owners in the entire project area. In order for Transportation
to consider recommending to the Planning and Transportation Commission that the project
be approved for permanent installation, support must be indicated by a simple majority (50+
percent) of project area survey responses, including 50+ percent of all_ households on the
primary street(s).
Planning and Transportation Commission andlor City Council review of
results of trial plan and decision on permanent installation.
Transportation prepares a report to the Planning and Transportation Commission on the
outcome of the trial plan. If the trial was successful, City staff prepares an environmental
review based on the results of the trial. Residents and property owners of the project area are
notified. If the minimum project area support described in Step 10 is not obtained, or if the
plan was clearly not successful as described in Step 9, Transportation will recommend
removal of the trial traffic calming plan. Trials on local streets that do not involve street
closures or diverters can be recommended for permanent installation by the Planning and "
Transportation Commission, with final approval by the Director of Planning and Community.
Environment. Trials of all other projects require review by both the Commission and City
Council, with final approval resting with the City Council. In both cases, the Commission
and/or Council listens to public testimony, discusses the project, and recommends whether
the trial plan should be removed, modified, or made permanent. If the decision is made not
to approve a permanent installation of the traffic calming plan, the project ends at that point,
unless the Commission or Council directs that the process return to Step 4 to select another
alternative.
12.Design and implement permanent plan and conduct follow-up evaluation.
The permanent installation is designed and bids are solicited for construction. The design
might also need to be confracted out, in which case bids would also need to be solicited for
the design work. Meetings with residents may be needed for designs of permanent measures.
.City Council approval is required for consultant and construction contracts exceeding a
certain amount. A follow-up evaluation of the effectiveness of the plan may be conducted up
to three years after permanent installation. Congratulations! The project is now complete.
Traffic Calming Program.
Page 21 DRAFT
April 9, 2001
PATCP. 12
Tim~ Line. Most spot treatment projects will require about ten months to reach approval for a trial
installation (Steps 1 - 6). The remainder of the process--designing, implementing and evaluating the
trial, and continuing through approval, design and installation of the lrmal plan, will take
¯ approximately an additional 10 - 14 months, for a total elapsed time of 20 - 24 months. Projects
consisting only of speed humps, with a staff-approved trial and no final design requirements, would
require only about 18 months. Complex projects would take at least twice as long as the above time
frame, due to the need to obtain City Council funding, and the much greater complexity of those
projects.
The above time estimates assume that there are sufficient City funds and staffing to handle the
project workload. If there were a high citizen demand for projects, a project might be on the initial
project waiting list up to 24 months. If construction funds were insufficient in any given year, an
additional wait of 12 - 24 months might occur (one or two funding cycles) for construction of trial
and/or permanent traffic calming measures.
Resident Funding of Permanent Installation. If residents desired to speed up the final construction
process, the City would consider full (not partial) resident or property owner funding of a traffic
calming project. Project area or primary street residents and property owners determine how to
collect the money. Any number of residents and/or property owners can contribute (full funding
could even be provided by just a single resident), and residents are solely responsible for amassing
the required amount before presenting it to the City. A deposit of 50 percent of the estimated project
costs must be made to the City before the final design, of the project can begin. Residents must
deposit the remaining 50 percent of the estimated project costs with the City before construction
begins. Resident funding will be received only for approved traffic calming projects, with the
purpose being to speed up permanent construction. Resident funding will not be used to speed up
the qualification and study process or to qualify otherwise unqualified projects.
Traffic Calming Program
Page 22 DRAFT
April 9, 2001
PATCP. 12
VII.NEIGHBORHOOD TRAFFIC CALMING REQUEST
MINIMUM QUALIFYING AND RANKING CRITERIA
Qualifying Criteria
Requests for traffic calming on residential local and collector streets may be made for one or more
candidate streets. Local and collector streets are illustrated in Figure 2. Requests involving one or
a few streets (i.e., for "spot treatment") must include a petition signed by 25 percent of the
households, as described in Step 1 of Chapter VI. The street(s) for which traffic calming is requested
.must have at least 50 percent of the total street frontage developed in, or zoned or, single or multiple
family land uses. In order for a request for spot treatment traffic calming projects to be eligible for
this program, at least two of the following five criteria must be satisfied:
(a) Minimum 85th percentile speed of 32 mph for local streets, and 35 mph for collector streets;3
(b) Minimum volume of 1,200 vehicles per day (vpd) for local streets and 4,000 vpd for collector
streets;4
(c) Location within 1,000 feet walking distance of a school, senior citizen facility, facility for the
disabled, park, community center, or other site with significant pedestrian activity;
(d) Evidence (survey or field evaluation) of significant cut-through (i.e., through or non-
neighborhood) traffic;
(e) Unusual accident history (as defined by six or more crashes, or one fatal crash, in the prior three
consecutive years - crashes due to parking~ vehicle equipment, drug/alcohol, and certain other
causes clearly not solvable by traffic calming will usually not be counted.)
Ranking Criteria
Requests that meet the minimum qualifying criteria are placed on a project list according to the
following ranking scheme. Due to funding and staffing concerns, the Transportation Division will
place complex/neighborhood projects on a separate project list to. be forwarded annually to the
Planning and Transportation Commission and the City Council for special funding, staffing, and
authorization to proceed.
Speed at, or up to 10% above, the minimum speed criterion--one street:
Speed at, or up to 10% above, the minimum speed criterion--two+ streets:
Speed more than 10% above the minimum speed criterion--one street:
Speed more than 10% above the minimum speed criterion --two+ streets:
Volume at, or up to 20% above, the minimum volume criterion--one street:
3.0 points
6.0 points
4.0 points
8.0 points
1.5 points
3 Speed measurements will be multiplied by_+5 percent to allow for measurement error and random daily variability. If
any point in the resulting speed range .meets or exceeds the above minimum, this criterion will be satisfied.
4 Volume measurements will be multiplied by_+10 percent to allow for measurement error and random daily variability.
.If any point in the resulting volume range meets or exceeds the above minimum, this criterion wi!l be satisfied.
Traffic Calming Program
Page 23 DRAFT
April 9, 2001
PATCP. 12
Volume at, or up to 20% above, the minimum volume criterion--two+ streets: 3.0 points
Volume more than 20% above, the minimum volume criterion--one street: 2.0 points
Volume more than 20% above, the minimum volume criterion--two+ streets: 4.0 points
Within 1000 feet walking distance of a school, senior citizen facility, facility
for the. disabled, park, community center, or other site with significant
pedestrian activity---one site:2.5 points
Within 1,000 feet walking distance of a school, senior citizen facility, facility
for the disabled, park, community center, or other site with significant
pedestrian activity--two+ sites:5.0 points
Evidence of significant cut-through traffic--one street:.1,0 points
Evidence of significant cut-through traffic--two+ streets:2.0 points
Request supported by more than 50% of households on 9roblem street(s):2.0 points
Traffic Calming Program
Page 24 DRAFT
April 9, 2001
PATCP. 12
VIII. REMOVAL OF,TRAFFIC CALMING MEASURES
Traffic calming measures may be subject to removal at the trial or permanent stages for various
reasons, including conformity with the Americans with Disabilities Act (ADA), impacts on the
emergency services, safety problems, unacceptable traffic impacts, or by request of affected
residents.
.Conformity with ADA. Traffic calming measures that force vertical movements for drivers
(speed humps, speed tables, raised crosswalks, and raised intersections) could have a harmful
effect on persons with certain disabilities, under certain circumstances. A person with a disability
protected by the ADA might move residence to a street where one of these measures has
previously been installed or is in a trial stage, and where there is no route of ingress and egress
for the new resident that does not require travel over one of these measures. If that person
requests removal of one or more of these measures because that person reasonably demonstrates
that the measure aggravates the protected disability, the request will be evaluated and granted by
the Chief Transportation Official (CTO). As part of that decision, the CTO would determine if
removal of the device would negatively impact the overall traffic calming plan. If a potential
negative impact were expected, the CTO would direct that a monitoring program be conducted
to determine the impact of the change. If a negative impact were found, the CTO would direct.
that a project be initiated, generally following the procedures in Chapter VI, to evaluate a
modification of the traffic calming installation. The goal would be to reduce or eliminate the
impact of the device removal.
Impacts On the Emergency Services. During City consideration of any potential trial or
permanent installation of traffic calming measures; the Fire Department will evaluate impacts on
its mission with regard to delay in providing fire and paramedic services. The Fire Department is
particularly concerned withspeed humps and other vertical measures on local and collector
streets. A traffic calming plan that is expected to create unacceptable delay for the Fire
Department would not be implemented. If a trial traffic calming.plan were implemented and
then found to introduce unacceptable delays in emergency response, the trial would be adjusted
accordingly, or even be removed. After the traffic calming plan has been tested, evaluated,
approved, and permanently installed, it is unlikely that the Fire ’Department would later find that
the plan is causing unacceptable delay impacts. If, for that reason, the Fire Department requests
modification or removal of a permanent traffic calming plan, Transportation will take the request
to the Planning and Transportation Commission and City Council for a recommendation or
decision, whether or not the original installation was approved by those bodies. If modification
of the plan were directed, Transportation would follow the same procedure in Chapter VI under
which the plan had been originally installed.
Traffic Calming Program
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April 9, 2001
PATCP. 12
Unacceptable Impacts. At any time during a trial period or at the end, if Transportation determines
that the trial is. clearly having substantial unacceptable impacts .(e.g., traffic diversion substantially
exceeds the 25 percent threshold, substantial resident comPlaints, crashes, substantial delays to the
emergency services), the procedure would return to Step 4 (working group meeting) to make
modifications and repeat the trial. If it appeared that modifications could not be developed that
would resolve the problem(s), the Chief Transportation Official would direct that a staff-approved
trial be abandoned and the project would end at that point, even if residents were in favor of the
trial. If commencement of the trial required review by the Planning and Transportation Commission,
City staff would prepare a report to the Commission recommending that the trial be abandoned. If
problems were serious enough, Transportation could end the trial and remove the trial measures
without notice, even if residents were in favor of the trial.
Residents" Request. Once a traffic calming plan has been developed, successfully tested in a trial
installation (and changes made if necessary), and permanent measures designed and installed, it
is unlikely that anyone would request removal of the installation. This has not occurred with any
traffic calming projects in Palo Alto. However, there could be circumstances under which
residents would desire such a removal. City staff would handle such a request on an ad-hoc
basis, following the same procedure in Chapter VI under which the traffic calming plan had
originally been installed. Usually, only residents from the project area, as defined in Step 2 of
Chapter VI would be eligible to make the request. The same percentage of project area
households that is required to vote for installation of a plan would be required for its removal. A
request for removal would be taken to the Planning and Transportation Commission and City
¯ Council for discussion and action, whether or not those bodies approved the original installation.
Traffic Calming Program
Page 26 DRAFT
April 9, 2001
PATCP. 12
Draft pp
INVENTORY OF NEIGHBORHOOD
TRAFFIC CALMING MEASURES
Neighborhood Traffic Calming Program
City of Palo Alto
Department of Planning and Community Environment
Transpoffation Division
April 9, 2001
Inventory of Neighborhood
Traffic Calming Measures
For Local and Collector Streets
Table of Contents
Introduction
Description and Illustrations of Traffic Calming Measures
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Waming and Specialty Signs
Stop Signs [technically not a traffic calming device but may be used in traffic calming plans]
Speed Limit Signs
Gateways ¯
Textured Crosswalks
Special Striping, Narrow Lanes
On-Street Parking
Bulbouts, Chokers, Curb Extensions
Median Island Slow Points
Raised Intersections**
Traffic Circles
Serpentine Streets, Chicanes*
Speed Tables and Raised Crosswalks**
Speed Humps*
Slow Streets*
Turn Prohibition Signs
Diagonal Diverters, Forced Turn Channelization, Median Barriers*
One-Way (Half) Street Closure*
Full Street Closure*
*Not permitted on Collector streets unless an exception is granted by the Fire Department and/or the
Transportation Division. All speed hump projects will be reviewed by the Fire Department before approval is
given.
**Permitted on collector streets at intersections after general Fire Department review. Speed tables and raised
crosswalks may be permitted on collector streets midblock if Fire Department approves the specific location.
III. Directory of Traffic Calming Web Sites
Inventory of Local and Collector Street
Traffic Calming Measures
I. Introduction
In Palo Alto, traffic calming is defined as the combination of mainly physical measures that
reduce the negative effects of motor vehicle use, alter driver behavior, improve safety for non-
motorized street users, and improve neighborhood livability. This traffic calming program does
not include the educational and enforcement programs that are provided by the Police
Department and the Transportation Division. Many residents feel that education and enforcement
do not have a permanent impact on driver behavior; thus, this traffic calming program is focused
on physical measures that should cause noticeable, lasting changes in driver behavior.
The following pages describe and illustrate traffic calming measures that may be used on local
and collector streets in Palo A!to. For a variety of reasons, not all measures may be acceptable or
desirable in all situations. Some measures are not acceptable for use or/collector streets or on
certain local streets determined by the Fire Department to be important emergency response
routes. The determination of which measures best suit which application will be worked out
between neighborhood residents, the Transportation Division and Fire Department, following the
guidelines and qualifying criteria described in the Neighborhood Traffic Calming Program
document. Many of the measures described herein may be used in combination with each other,
and there are also many design ,variations of each measure. Residents are encouraged to see and
experience traffic calming measures that are installed in Palo Alto and nearby communities--
some locations are included in the description of each measure. The .Transportation Division has.
an extensive library of traffic calming books and photographs that residents can peruse.
Additionally, the World Wide Web sites listed at the end of this inventory provide extensive
additional information and illustrations.
The traffic calming measures in this inventory are listed generally in order of increasing
effectiveness at reducing the volume Of shortcutting traffic and/or speeds. The least effective
measures are usually "passive," meaning that drivers can choose whether or not to obey them.
The most typical examples of passive measures are traffic signs and striping. The next level is
the "active" measures that physically constrain the driver to certain paths or areas in the
roadway. The most desirable and effective active measures are those that force drivers into
horizontal or vertical movement, therefore causing drivers to reduce speed--the primary objective
of traffic calming. Reduced speed translates into increased travel time that, in turn, may decrease
traffic volumes because drivers may abandon a slowerroute. Some examples of these measures
are traffic circles and speed humps. The most drastic active measures are those that partially or
completely block traffic movements, with dramatic effects on traffic volume and the incidence of
speeding. Partial and full street closures are examples of this type of measure.
For further information, please contact the City of Palo Alto Transportation Division at
(650) 329-2552.
1. WARNING AND SPECIALTY SIGNS
1. WARNING AND SPECIALTY SIGNS
Warning signs are standard signs prescribed by the State to warn of specific obstacles and conditions,
such as curves, bumps, driveways, pedestrian crossings, advisory speed, etc. Usually such a sign would be
installed only because of the existence of the particular condition. Many traffic calming devices require
installation of warning signs to warn drivers of the impediment. Warning signs by themselves are usually
not considered to be traffic calming devices.
Other warning signs are non-standard in that they are not recognized by the State. Some can be termed
"specialty" signs, and may carry messages such as "Residential Street", "Children Playing", or novel
messages such as odd speed limits and other non-standard messages. Somenon-standard signs may be
necessary to warn drivers of unusual traffic calming devices. Novel messages may catch the driver’s eye a
few times, but aider a while novelty wears off. In general, the messages of all these signs can wear off
quickly on regular drivers on a particular route, whether they are local residents or shortcutting drivers.
Palo Alto discourages non-standard signs except where they must be used to warn of an unusual device.
Some specialty signs warn of conditions that most drivers should presume to exist in every neighborhood
and/or are inherently obvious. Examples are the two given above. If such signs were used extensively, but
not everywhere, drivers could come to think that their absence indicates that those conditions are not
present when they might actually be present. In general, specialty or novel signs can be considered to be
traffic calming devices, but their long-term impact is minimal in all respects. Each sign installation costs
approximately $150.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
2. STOP SIGNS
Berkeley
Seattle
2. STOP SIGNS
A stop sign is not considered to be a traffic calming device, but is included here because stop signs could be
included in a traffic calming plan under certain circumstances and because many residents request
installations of stop signs for traffic calming purposes. The purpose of a stop sign is to assign right-of-way
at intersections with significant traffic volumes or safety problems. Official warrants, describe the
conditions under which stop signs should be installed. Because it assigns right-of-way, th~ stop sign is the
most imPortant regulatory sign in traffic engineering. If drivers disregard it, severe consequences for "
drivers can result. In order to maintain driver respect for the stop sign and to not dilute its importance, it
must not be used inappropriately o~ too frequently. Nevertheless,. stop signs have,been installed for
neighborhood traffic calming purposes, oftei] at the i~sistence of residents and often without the
recommendation of the City traffic engineer. Ironically, a common resident complaint is drivers running
stop signs. Stop signs are appropriate in traffic calming projects at some locations where accidents occur
due to unresolvable visibility or right-of-way problems. The best example of stop signs used primarily for
traffic calming purposes is Palo Alto’s "guard and go" stop sign system that was implemented Citywide in
1961.
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
Isolated stop signs are not effective at reducing volumes. If a series of stop signs is
installed, and if there is an alternative and faster collector or arterial route, the volume
of non-neig~hborhood traffic can be reduced.
¯ Palo Alto’s 1976 stop sign study showed that, with stop signs installed every other
block, 85th percentile speeds ranged from 23-37 mph between stop signs, with speeds
at or !ess than the25 mph residential speed limit at only 3 out of 60 locations. The
conclusion of the study was that speeds with the guard and go system were as fast as,
or faster, than they would be without it.
¯ If stop signs were installed at every block, mid-block speeds might be reduced further
than noted above, but. widespread disobedience of stop signs would be expected. Even
with stop signs every other block, the stop sign study found that over 70 percent of
traffic does not come to a full stop at intersections, with speeds through the intersection
ranging from 2.5 to 10 mph.
¯ Speeds are reduced within about 200 feet of the intersection at which they are
installed.
Stop signs increase emissions, fuel consumption and noise.
As noted in the stop sign .study, safety is compromised by too many stop signs, because
of the disobedience caused by having to stop frequently for no apparent reason.
Minimal impact on emergency response.
As with any traffic sign, aesthetics is usually degraded. A single sign has minimal
negative visual impact. Pavembnt legends (stop bar and stop legend) contribute to the
negative visual impact.
Maintenance for a single sign and stop bar is relatively small, but compounds for a
series of signs.
$200 for new sign and legend installation.
Generally unpopular with bicyclisis, because a series of complete stops can
substantially lower average speed.
Appendix." Inventory of Neighborhood Traffic Calming Measures May 10,2000
3. SPEED LIMIT SIGNS
SPIED
LIMIT
2
3. SPEED LIMIT SIGNS
"~11 residential local and collector streets in Palo Alto have a prima facie speed limit of 25 mph, which is
typically not posted on local streets. Residents often request the post~g of speed limit signs for traffic
calming purposes. Usually this request is denied, as most drivers know that the residential speed limit is 25
mph. Fu~.~ermore, if signs were posted on some local streets but not others, drivers could think that only
the post~i streets had the 25 mph limit. 25 mph speed limit signs might be posted on major collector streets
if the physical characteristics of the street communicate to drivers that a higher speed would be acceptable.
In general for all types ofsigns, their passive nature and the fact that regular drivers of a route may
eventually not consciously notice them, the result is typically insignificant impacron driver behavior.
Traffic ......No impact .....
Volume
Speed Studies and field observations in Palo Alto and other cities show that drivers.’ speeds
include relatively little consideration for the posted speed limit. Absent sustained
police enforcement, drivers tend to travel at a speed at which they feel is comfortable
for the circumstances. However, this may not be the speed that residents of the street
feel is comfortable and safe while they are engaging in "residential activities" not in
their vehicles. Usually more active devices than signs are needed to encourage or
force drivers to slow down.
Minimal impact.Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Minimal impact on traffic safety. No impact on emergency services.
Incremental negative aesthetic impact from each additional sign.
Maintenance Incremental increase in maintenance for a single sign.
Approximate $150 per new sign installation.
Cost
Appendix." Inventory of Neighborhood Traffic Calming Measures May 10,2000
4. GATEWAYS
Gateway
University Drive, Menlo Park
Gateway
Ninth Avenue, Fair Oaks
4. GATEWAYS
A gateway consists of an architectural or roadway feature on each side and/or in the center of a roadway,
used primarily to indicate to drivers that they are entering a special area, usually a residential neighborhood
in the case of traffic calling. The most effective gateways include vertical elements such as trees or
columns. Gateways may be formed by curb bulbouts, fences, poles, signs, artwork, and other features
which can be combined with each other. If the gateway were narrow, it would reduce spe~: ~ at that point
and could reduce through traffic. Local examples: Fair Oaks neighborhood near Athertoz~i entrance to
Lindenwood neighborhood, Atherton; Cambridge west of El Camino Real, and University south of Middle
in Menlo Park.
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
’Reduction in-traffic volume wouldn.ormally be small because gateways do not occur in
a series, nor do they typically reduce speeds. The narrower the gateway, the greater the
opportunity for some volume reduction.
If a gateway is substantially narrower than the normal roadway width, some speed
reduction is possible at the gateway only. Refer also to above comments about volume
reduction.
Typically there would be minimal impacts on noise production, air quality or energy
’consumption. If the gateway were particularly narrow, especially if two-way traffic
could proceed in only one direction at a time, some increased noise could result from
braking and acceleration in the gateway area.
Accident data is generally inconclusive. There is some evidence indicating that
accidents may be reduced with gateway treatments, even extremely narrow ones.
Minimal impact on the emergency services. "
Normally, gateways add to the aesthetic appeal of the area, due to the architectural
features or landscaping. Special signing that would reduce aesthetic appeal is usually
not required unless the width of roadway is reduced to a one-way crossection.
All traffic calming devices require maintenance. Gateways usually do not create
interference with roadway surface work. For landscaped gateways, refer to
maintenance descriptions for landscaped devices.
There is a wide range of costs for gateways depending on their design. A simple
wooden fence such as used in the Fair Oaks arga could be co~nstructed for
approximately $1000. Designs involving curb bulbouts would cost from $20,000 to
$40,000. High-quality designs involving architectural features such as columns and
portals could cost around $100,000.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
5. TEXTURED CROSSWALKS
Textured Crosswalks
Downtown Menlo Park
5. TEXTURED CROSSWALKS
Crosswalks, whe~ midblock or at intersections, can be textured by means of special pavers or other
treatment. When used as part of a larger traffic calming project, the primary intention is to impart a
message to the driver that the area being traversed has some special identity, such as an area where
pedestrian traffic is frequent, and/or that special driving attention,is required. A textured crosswalk can be
used in isolation, usually for the specific purpose of calling greater driver attention to the specific
crosswalk. Local examples: University Avenue between Cowper and High (Palo Alto), Downtown
Redwood City and Menlo Park (none are neighborhood calming projects).
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
No change in traffic volume would normally be expected.
Only minor reduction in speeds would be expected, if any.
Depending on the type of textured treatment, some amount of increased noise is likely.
No impact on air quality and energy consumption.
No data is available on traffic safety impacts. No impacts on emergency response
vehicles.
Special pavement treatments add to aesthetic appeal of a street or intersection.
Additional signing is not required for the sole purpose of converting typical asphalt to
specia! paving.
Maintenance Increased maintenance, possibly including stockpiling of special materials, is required
for special .pavement treatments. Removal and replacement may be required for street
resurfacing.
Approximate $10,000
Cost
Other By themselves, textured crosswalks are not particularly effective traffic calming
devices. They are best used in conjunction with other traffic calming measures, such as
bulbouts, raised crosswalks and raised intersections. Another method of calling
attention to a crosswalk is the use of lights installed in the pavement that are activated
when a pedestrian wishes to cross. However, such a device is usually used as a specific
crosswalk safety device rather than for the broader purpose of traffic calming.
Appendix." Inventory of Neighborhood Traffic Calming Measures May 10,2000
6. SPECIAL STRIPING AND NARROW LANES
Narrow Lane
Stanford Avenue, Palo Alto
6. SPECIAL STRIPING/NARROW LANES
Some geometric design features employing islands and circles to call traffic can be installed with traffic
striping and/or pavement markers to form the island or circle. Such installations are relatively inexpensive,
low-maintenance, and do not interfere with drainage, and street sweeping. However, because they can be
driven over, and because they produce no visual obstruction when seen fi’om a distance, they have ’-’
relatively small impact on driver speeds and ~iumes. In’this regard~ use of striping to achieve traffic
calling can be considered a "passive" measure, like installing signs, because drivers are not physically
forced to change their behavior. Regular Police Department enforcement is usually required to produce
effective results from such passive devices.
Traffic lanes may be narrowed merely by changing the striping layout to reduce, for example, 12-foot lanes
to 10-foot lanes. If appropriate, bicycle lanes can be added, to a street, with consequent reductions in width
of the other lanes. Narrower lanes may give drivers the impression era narrower street and/or less room for
maneuvering, thereby potentially reducing speeds. The lack of physical width restrictions (such as raised
islands, landscaping, parked cars) results in substantially less impact on driver behavior than the other
physical measures.
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
¯ A narrow lane on some major arterial streets in Pale Alto does not appear to have
reduced traffic volumes noticeably. Minimal impact expected from devices created by
striping only. ¯
A narrow lane on some major arterial streets in Pale Alto does not appear to have
reduced traffic speeds noticeably. Minimal impact expected from devices created by
striping "only.
Minimal impacts would be expected.
Minimal impacts would be expected.
No impact on aesthetics if the amount of striping remains the same. If new striping
were added, the impact on aesthetics would be moderately negative.
Maintenance Any additional striping requires increased maintenance for striping. Street resurfacing
becomes more costly with increased replacement striping.
Approximate Cost depends on the length of striping removed and installed and varies depending on
Cost the overall size of the project. Removal and replacement of thermoplastic striping costs
approximately $1.00 per linear foot,
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
7. ON-STREET PARKING
Palo Alto
Seattle
7. ON STREET PARKING
Reduction in width of traffic lanes, especially when physical objects are brought closer to the outside edge
0fthe traffic lane, can reduce driver speeds, as drivers perceive that there is less width for maneuvering and
sight distance is reduced. Parked cars are especially conducive in this regard, as they indicate numerous
hazards, such as the possible presence of pedestrians, car doors opening, cars pulling out, children
appearing suddenly from between cars, and the "wall effect" causing drivers to feel that the lane is
narrower than it really is. A row of parked cars also provides a buffer between pedestrians on the sidewalk
and moving vehicles. Adding on-street parking is usually only possible if the demand is already present and
parking has heretofore.been prohibited. On-street parking areas can be created on alternating sides of the
street, with traffic lanes shiftingback and forth t6 accommodate the parking areas (refer to description of
"serpentine street"). If sufficient width is available, diagonal parking can be introduced, producing a
different "feel" to the neighborhood.
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Response
Aesthetics
Maintenance
Approximate
Cost
No data specific to this measure is available.
No data specific to this measure is available.
Minimal impacts would be expected.
Minimal negative impacts on driver safety would be expected. In some cases of very
narro~v lanes, drivers may become more conscious of opposing traffic and, in
combination with reduced speeds, safety may increase. Heavy on street parking,
however, introduces safety problems for cyclists: narrower lanes may not allow a
cyclist and a driver to share the lane, and the increased probability that a driver will
open a door into the path era passing cyclist. Minimal impacts on emergency services,
unless the combination of high traffic volume and narrow lane widths is such that
emergency vehicles cannot f’md enough room to pass waiting cars.
Heavy on-street parking, to most observers, has negative aesthetic impacts, such as .
increased number of signs, reflections from metal and, glass, blocking views of
landscaping, damaging trees, and increased noise and litter.
Increased maintenance is required for any signs and striping used to control on-street
parking, and special signs and programs must be introduced if street sweeping is to be
conducted without parking present.
Depends on how it is instituted. Typically, the primary cost would be for new signs at
approximately $150 each.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
8. BULBOUTS, CHOKERS, AND CURB EXTENSIONS
Bulbout
Park Blvd/Lambert
Curb Extension with drainage
and landscaping -
Milvia Street, Berkeley
Bulbout
Park Blvd/Lambert
Bulbout
Park Blvd between
Grant & Sheridan
Bulbout not attached to curb - Willow Road, Menlo Park
8. BULBOUTS, CHOKERS, CURB EXTENSIONS
Bulbouts, bumpouts, curb bulbs, chokers, curb extensions and neckdowns are synonymous terms for an
extension of the curb into the former paved street area, typically for th~ width of a parallel parking space.
The 10w-cost (budget) design does not literally extend the curb line; rather a gap remains between the
former curb line and the new islands, in order to maintain gutter flow. Bulbouts may be installed at
intersections or midblock, on one or both sides of the street. They usually do not impede or redirect traffic
flow; rather, they typically reduce the width of the traveled way to the minimum required for two-way
traffic (in Palo Alto, they willnot be used to narrow the street to less than the minimum of 20 feet required
for two-way traffic, unless .used ~}nly .for one-way, traffic)..They may .be used for numerous purposes,
including (i) reducing curb radii at intersections to slow turning traffic, (ii) enhance pedestrian safety and
visibility at pedestrian crossings, Off) provide extra space for landscaping and sidewalk amenities; (iv)
possibly reduce driver speed by creating a sense of narrowness, (v) create a neighborhood gateway feature.
For bulbouts u~ed on one side of the street in conjunction .with offset centerlines, refer to discussion for
serpentine streets and chicanes. Bulbouts may be short (e.g. about one car length), and could be much
longer (e.g., a large portion of a city block). Examples of intersection bulbouts: University Avenue
(Downtown Palo Alto); Santa Cruz Avenue (Downtown Menlo Park). Examples of longer bulbouts: Park
Boulevard between Grant Avenue and Lambert Avenue (Palo Alto). None of the above examples are
neighborhood traffic calming projects.
Traffic Studies have shown that bulbouts reduce traffic volumes only if they narrow the street
Volume to less than two lanes with two-way traffic, or are installed frequently along a
considerable length of street. Thus, in most installations, bulbouts are not considered to
be a serious volume reduction measure.
Speed The effect on speeds is similar to the above discussion on volumes. In most
installations, bulbouts are not considered to be a serious speed reduction measure,.
except for turning traffic when bulbouts are used to shorten comer radii at
intersections.
No substantial effects have been identified.Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
When used at intersections and other pedestrian crossings, pedestrian safety arid
visibility is enhanced by bringing waiting pedestrians Out closer to the traffic lane, and
shortening the crossing distance. On higher-volume streets, bicyclists may be
adversely affected when they are forced to share the narrow travel lane with drivers.
Providing bicycle lanes through the bulbouts essentially defeats the primary purpose of
bulbouts, which is to substantially narrow the traveled way. Bulbouts do not noticeably
interfere with movement of emergency vehicles, provided that the minimum turn radii
are provided at intersections.
Bulbouts may be landscaped, adding greenery where asphalt was formerly present.
Required signs and reflective devices may be unattractive.
Every traffic calming device requires .maintenance. Automatic irrigation decreases the
need for landscaping maintenance and watering. Depending on the design, bulbouts
may interfere with street sweeping and gutters may clog.
Budget design (not attached to curbs): $19,000 per pair. High aesthetic/low
maintenance design (attached to curb): $40,000 per pair (higher or lower depending on
new storm drainage construction). The above estimates are for short bulbouts as might
be used at intersections. Longer bulbouts would cost proportionately more.
Parking spaces will be eliminated in bulbout locations, but may be less at intersections
where parking may alread3i be prohibited. At intersection, minimum comer radii
requirements for small trucks and emergency vehicles may reduce the potential for
shortening pedestrian crossing distance.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
9. MEDIAN ISLAND SLOW POINTS
Portland, Oregon
9. MEDIAN ISLAND SLOW POINTS
Raised islands can be installed along the centedine of a street, narrowing the street and lane widths, either
at intersections or midblock. Traffic lanes wilt be offset towards the curbs. The resulting narrowing and
moderate horizontal deflection can lower speeds in the vicinity of the median. Because horizontal
deflection is usually not extreme, speed reduction is not large. Therefore, these devices do not substantially
reduce trafc volumes~ The mild horizontal deflection does not seriously slow down emergency vehicles.
Thus, this measure may be used on collector streets. Curb bulbouts could be used in conjunction with
median islands to create a greater feeling of constriction, thus reducing speeds more. The median islands
can be used in conjunction with crosswalks, with the median serving as a pedestrian refuge. Another
variation is the angled slow point, wherethe.median.island and~~rresponding bulbouts are angled to
produce greater horizontal deflection, thus greater speed reduction.
Traffic Traffic volumes may be reduced by about ten percent if a series of slow points is
Volume.installed.
Speed Speeds may be reduced by about five percent, depending on the "before" speed and the
severity of the horizontal offset.
Minimal changes in noise, air quality and energy consumption.’ Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
When used as pedestrian refuges, median slow points improve pedestrian safety by
slowing traffic and breaking the crossing into two segments. If the medians areused on
higher volume streets that are also bicycle routes (e.g. exceeding about 4000 vpd),
bicyclists may be adversely affected when they have to share the travel lane with
vehicles around the circle. With a series of circles, bicyclists may benefit from overall
speed and volume reductions. Bike lanes could be maintained through the slow point,
but the added width offsets the effectiveness of the narrowing in slowing down
vehicles. Median slow points may be used on emergency response routes. The angled
slow point cannot be used on emergency response routes because of the more severe
narrowing and horizontal deflection.
Median islands may be landscaped, adding greenery where asphalt was formerly
present. From a distance, trees may lead drivers to believe that the street is somehow
obstructed, and therefore may help reduce volumes. New signs are required, adding
visual clutter.
Each traffic calming device requires maintenance. Automatic irrigation decreases the
need for landscaping maintenance and watering. Because medians are located in the
center of streets, drainage and street sweeping are not affected.
The standard minimum-width median design includes landscaping and automatic
irrigation, at about $25,000 for a 40-foot length. A hardscape design would cost about
$20,000. Longer medians would cost proportionately more.
Medians used at intersections must be designed to allow for turns by large vehicles,
possibly affecting the location and effectiveness of the medians. Parking will probably
have to be prohibited in the vicinity of the medians.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
10. RAISED INTERSECTIONS
I
I
I
Raised Intersection
Andronico’s Market - Quarry Road, Paio Alto
10. RAISED INTERSECTIONS
A raised intersection is somewhat analogous to a midblock speed table as a speed reduction technique. The
entire intersection is raised fi’om three to six inches above grade, and may be given a special pavement
treatment. This technique has been used extensively in Europe. In the U.S., they have more often been
used as enhancements for pedestrian safety and aesthetics in shopping areas, rather than for neighborhood
traffic management. Local examples: Main entrance to Andronico’s Market (Stanford Shopping Center);
Central Park Area (Stanford West Apartments).
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
No data is available, but the volume reduction should be less than for speed humps and
tabl6s,.due to.the greater length, of.the plateau in the direction of travel .....
Minimal available data indicates minimal overall speed reduction, except at the raised
intersection itself.
Noise can increase due to braking, acceleration, crossing textured pavement, and
bouncing cargo in trucks. Minimal impact on air quality and energy consumption.
Pedestrians benefit at raised intersections because the street is raised to the same grade
.as pedestrians, making the area pedestrian territory and encouraging drivers to take
extra care. Due to the long raised plateau of raised intersections, and their location at
intersections, this measure is acceptable for use on collector streets. Fire trucks and
paramedic vans will have to slow to cross the raised intersection, but they usually slow
anyway at intersections.
Potential for improved aesthetics if special pavement treatment is used. Warning signs
may be required, which would degrade aesthetics.
Additional maintenance is required, especially for special pavement treatments. Raised
intersection interferes with street overlays, and may have to be removed for a
resurfacing project.
Actual data is not available. A rough estimate is $30,000 - $60,000 for asphalt
construction, including drainage work; and $40,000 - $70,000 for concrete/paver
construction, including drainage work. Over half of the above costs represents drainage
work.
Appendix." Inventory of Neighborhood Traffic Calming Measures May 10,2000
11. TRAFFIC CIRCLES
Traffic Circle
Lytton/Fulton, Palo Alto
Trdffic Circle
Park Ave/Park Blvd
Traffic Circle
Park Ave/Park Blvd
11. TRAFFIC CIRCLES
As used for traffic calming .purposes, traffic circles are relatively small circular or oval islands (usually
landscaped) placed at the center of intersections of local and/or collector streets. Their primary purpose .is
to reduce speeds through an intersection or, if used in a series, reduce speeds for several blocks. Depending
on their design, traffic circles can also reduce conflicts at intersections. Because they are located in the
middle of two streets, they may give drivers on both streets the impression that the ~treets may not be
"through". They can be used with and without stop signs. Traffic circles are different from "roundabouts",
the iatter being a more formalized version of a circle which are usually installed on higher-volume streets
Though roundabouts reduce speeds through an intersection, their primary purpose is to facilitate traffic
flow rather .than discourage it. ~Local examples: Addison/Bryant, Lytton/F~lton, and Park Blvd/Park Ave
intersections (Palo Alto); Fair OaksNeighborhood (near Atherton). .~
Traffic Reduced speeds and the appearance of obstructions in the roadway will reduce
Volume volumes by about 20% for a series of circles; minimal reduction for a single circle.
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic.
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost ,
Other
Reduced about 100-200 feet before and after the circle, compared to no previous traffic
controls at intersection. Reduced to about 15 mph at the circle. A series of circles at
several intersections will reduce speeds between intersections to 25-30 mph, depending
on spacing.
If a circle replaces stop signs, noise, fuel consumption and emissions will decrease. A
series of circles, by reducing overall speeds, will have the same effects over a length of
street.
Intersection accidents can be decreased where circles completely replace stop signs.
They may increase hazards for pedestrians, as vehicles are forced close to (but n6t
into) the pedestrian crossing area. If the circles are used on higher volume streets that
are also bicycle routes (e.g. exceeding about 4000 vpd), bicyclists, may be adversely
affected when they have to share the travel lane with vehicles around the circle. With a
series of circles, bicyclists may benefit from overall speed and volume reductions.
Some drivers, especially those of large vehicles, may turn left in front of the circle and
therefore encroach into the oncoming traffic lane. Circles do not block access to any
street. They will reduce speeds of emergency response vehicles, .but they must reduce
speeds anyway at intersections. Circles may be used on emergency response routes.
Circles may be landscaped, adding, greenery where asphalt was formerly present. From
a distance, trees may lead drivers to believe that the street is not a through street. New
signs are required, adding visual clutter.
Every traffic calming device requires maintenance. Automatic irrigation decreases the
need for landscaping maintenance and watering. Because circles are located in the
center of streets, drainage and street sweeping are not affected.
The standard traffic circle design for Palo Alto includes landscaping and automatic
irrigation, costing approximately $30,000. A hardscape design costs about $25,000.
In order to provide passage for large fire trucks, it is likely that parking will be
prohibited within about 50 feet of the intersection on all sides of the two affected
streets. Utilities in the center of many streets may not allow planting of trees, may add
to cost, and may cause other complications.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
12. SERPENTINE STREETS AND CHICANES
Seattle
Seattle
12. S ,IT PENTINE STREETS, CHICANES
A serpentine street or chicane is an artificially created curving two-way street on a naturally straight road
section. The curves can be created by offset centerline striping, a series ofbulbouts or parking areas
installed on alternating sides of the street, or by varying the size or shape of a series of median islands. The
length of the curve and the amount of side-to-side offset can be varied to obtain more or less reduction in
Speed. May be used midblock or at intersections. In addition to forced speed reduction, a serpentine
alignment that is created by landscaped islands gives the appearance that a street may not be a convenient
shortcut, thus possibly causing such drivers to awdd the route. If raised islands do not force the lane offsets,
many drivers would easily "straighten th~ curves’~ by not staying in the proper lanein the transition area,
thus reducing the effectiveness of this measure. Lanes Usually need to be narrowed in order to further
reduce the abili.ty of drivers to straighten the curves. In some cities, chicanes are used that are only a single
lane side for two-way traffic. Such severe artificial narrowing is discouraged at this time in Palo Alto
installations.
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response "
Aesthetics
Maintenance
Approximate
Cost
Other
If the design speed of the offset transition is similar to that for other devices such as
speed humps or traffic circles, and ifa series of offsets is used, volume reduction
similar to a series of those devices should occur, i.e., up to about 20 percent.
The offset transition can be designed for any amount of speed reduction. If the
horizontal offset is similar to that for other devices such as traffic circles, and if a
series of offsets is used, speed reduction similar to a series of those devices should be
obtainable, i.e., down to about 15 mph at the offset and down to 25-30 mph between
offsets. Effectiveness of this measure is reduced if drivers are able to "straighten the
CUrveS".
Noise could increase due to braking, accelerating, and passing over centerline pave-
ment markers at the curves. Noise would be reduced between curves due to slower
speeds. Minimal impact on air quality and energy consumption.
If the offsets are used at intersections, vehicles will be forced toward the curb close to
(but not into) the pedestrian crossing area. This could degrade pedestrian safety.
Drivers may not stay in the proper lane in the transition area, thus posing potential
safety problems. If lanes are narrowed, bicycles and motor vehicles may be forced
together in the transition areas, which could be a problem on higher volume streets. For
a short segment of serpentine street With mild and/or infi’equent horizontal offsets, the
impact on emergency services response times should not be great, as emergency
vehicle drivers can legally "straighten the curves" by driving down the center of the
roadway. Long sections may impact emergency services and thus may not be
appropriate for collector streets. A minimum width of 20 feet for two-way travel will
be maintained, as required by the Fire Department for emergency access and by the
Transportation Division for normal traffic flow.
Raised islands can be landscaped, adding greenery where asphalt was formerly present.
Painting of curbing may be required, and warning signs and reflectors are required,
decreasing aesthetic appeal.
Every traffic calming device requires maintenance. Automatic irrigation decreases the
need for landscaping maintenance and watering.. Depending On the design, bulbouts
may interfere with street sweeping and gutters may clog.
Cost depends heavily on length of serpentine street segment and types of devices used
to create the horizontal offsets. Refer to costs for devices such as bulbouts and median
island slow points.
This measure may be combined with other measures, such as speed humps, creating a
"slow street" (refer to separate description for slow streets). Parking spaces will be.
eliminated in bulbout locations, but may be less at intersections where parking may
already be prohibited.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
13, SPEED TABLES AND RAISED CROSSWALKS
Stanford Campus
Stanford Campus
Terman Drive, Palo Alto
13. SPEED TABLES AND RAISED CROSSWALKS
Speed tables and raised crosswalks are a gradual rise and fall in the pavement, typically to a maximum
height of three inches over a distance of 22 feet in the direction of travel. The central ten-foot section of the
table is flat. They may be used singly for a raised crosswalk, or in a series of two or more for the purpose of
speed reduction. When used as a raised crosswalk, the table should extend all the way to the curb, possibly
requiring new storm drainage construction and thus increasing cost considerably. Speed tables and humps.
usually taper down to street grade at the gutter, thus leaving the gutter open for normal drainage. The long
length of speed tables allows long wheelbase vehicles to cross with substantially less jolting than with the
12-foot humps, permitting higher speeds. Their longer profile results in higher speeds across and between
the devices compared to speed humps. T~aus these devices may be used on collector streets where Speeds
are usually higher, and whi~ch may also be emergency vehicle and transit bus routes. Usually, speed tables
and raised crosswalks are placed midblock, but a raised crosswalk may be permitted.at an intersection
under certain circumstances. Local examples: Terman Drive, Bryant Court (Palo Alto); Campus Drive
between Quarry Road and Ross Way (Stanford).
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety, .
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
Because speed tables do not reduce speeds as much as do speed humps, volume
reduction due to discomfort and slower travel times is less. A series of speed tables
will typically reduce volumes by about ten percent. This minimal traffic diversion to
other streets makes tables acceptable for use on collector streets.
Speed reduction depends on the spacing of tables. At the closest spacing of 200 feet,
85~ percentile speeds average about 30 - 33 mph between tables. 85t~ percentile speeds
at the tables themselves is reduced to about 25 to 30 mph. The less abrupt speed
reduction of tables makes them acceptable for use on collector streets, where speeds
are generally higher.
Slower speeds result in lower noise levels between tables. Noise levels at the tables
themselves may increase due to braking, accelerating and bouncing of cargo in trucks.
Minimal change in air quality and energy consumption.
Speed tables have not caused safety problems or liability claims. Long wheelbase
vehicles can more easily cross 22-foot tables than 12-foot humps, making them
acceptable for use on collector streets. If speed tables were to proliferate on collector
streets, this could eventually create a cumulative negative impact on emergency
vehicle response times, restricting their further installation.
Speed tables have nearly the same negative aesthetic impacts as speed humps, except
that the fiat portion of the table may be constructed with pavers or textured concrete.
The choice of acceptable materials may be severely limited by the need to withstand
the heavy vehicle loading that occurs due to the vertical deflection and heavier traffic
loads on collector streets.
Every traffic calming device requires maintenance. In addition, speed tables interfere
with street resurfacing and may have to be removed and replaced for such projects.
Any special pavement treatment on the top of speed tables may require more frequent
and expensive maintenance than asphalt.
About $5,000 - $8,000 per table when cons!ructed of asphalt. Special textured
pavement treatments on the top of the table and/or the ramps can approximately double
this cost. For raised crosswalks that extend across the gutters, an additional $5000 -
$10,000 per location would be required, depending on the extent of new storm sewer
connections.
The use of raised traffic calming measures on collector streets should be done with
restraint, due to the impacts on the response times of the fire and paramedi~ services.
The Fire Department may not permit the use of too many such measures because
collector streets are part of the emergency response street network. Parking is allowed
on and next to speed tables. Parking may be removed in advance of raised crosswalks
for visibility purposes.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
14. SPEED HUMPS
Speed Humps
Colorado/Gaspar
Speed Humps
Cowper/Oregon Expressway
Speed Hump
Ross Road/Colorado
Speed Humps
Cowper/Marion
14. SPEED HUMPS FOR LOCAL STREETS
Speed humps are a gradual rise and fall in the pavement surface, usually with a circular profile, to a
maximum height of three inches over a distance of 12 feet in the direction bf travel. Typically they are
installed in a series of two or more separated by at least about 200feet. This type of speed hump is installed
only on local residential streets. The primary purpose of speed humps is to produce sufficient discomfort to
a driver to reduce travel speed to 15 mph, which is posted as the advisory speed. The spacing of speed
humps is such as to result in an average 85t~ percentile speed of 25 - 30 mph between humps, depending on
the spacing. This design causes drivers to reduce speed, yet allows them to maintain control of their
vehicles. Drivers of longer wheelbase vehicles, such as trucks and buses, will normally have to reduce
.speeds to less than 15 mph;to avoid discomfort.’ For thisxeasoni:this type of speed hump is not usually
installed on transit, truck, or emergency vehicle routes. A primary characteristic of speed humps is their
high-speed control effectiveness at minimal cost. Local examples in Palo Alto: Cowper Street and Ross
Road south of Oregon Expressway, Marion and Colorado Avenues east of Cowper Street, Guinda Street
north of University Avenue, Palo Alto Avenue between Seneca and Chaucer Streets.
Traffic A series of at least three speed humps will typically reduce traffic volumes by about 10
Volume - 20 percent, with the reduction usually being in "through" traffic that can shift to
other routes.
Speed Speed reduction depends on the spacing of humps, ranging f~om approximately 200 to
600 feet. With the closest spacing, 85t~ percentile speeds are usually reduced to about
25 mph between humps. 85~ percentile speeds at the humps themselves is reduced to
about 15 to 20 mph.
Slower speeds result in lower noise levels between humps. At humps themselves, noise
can increase due to braking, accelerating and bouncing of cargo in trucks. Minimal
change in air quality and energy consumption.
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
Humps have not caused safety problems or liability claims. Long wheelbase vehicles,
including fire trucks, must cross humps very slowly to avoid significant jolting.
Drivers may drive in the gutter to partially avoid the humps. A series of bumps will
cause substantial delay in emergency vehicle response times, but does not reduce
access to streets. Palo Alto Fire Department has experienced at least one injury to a
firefighter who hit his head on the roof of the truck while passing over a hump. While
the Fire Department will allow humps to be placed on local streets, proliferation of
humps on many local streets may eventually cause a cumulative negative impact on
emergency vehicle response times. This impact may restrict further installation of
humps in the future. "
Because speed humps cannot be landscaped and must be clearly marked with signing
and striping, their negative visual impact is substantial.
Every traffic calming device requires maintenance. In addition, humps interfere with
street resurfacing and may have to be removed and replaced for such projects.
$3500 per hump, including signing and striping.
Speed humps are very common in California cities, with some cities having hundreds
of installations. Speed humps can be longer than 12 feet and have a flat top, in which
case they are referred to as raised crosswalks and speed tables (refer to separate
descriptions of these devices). Due to their effectiveness and low cost, the Palo Alto
traffic calming program provides preferences for speed hump installations under
certain circumstances. Parking is allowed on and next to speed humps,
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
15, SLOW STREETS
Slow Streets
Milvia Street, Berkeley
15. SLOW STREETS
The slow street employs a combination of traffic c, alming devices. On Milvia Street in Berkeley, the slow
street employs road bumps, bike lanes, a serpentine centerline, stop signs, and a one-way closure at one
end. The purpose of the design is to slow traffic.
Traffic Volume can be reduced by 10 - 20 percent in a 1 - 3 block segment of slow street.
Volume
Speed Speed reduction will depend on the individual traffic calming devices used. Speeds
will normally be reduced to about 25 -30 mph between devices and 15 - 20 mph at the
devices.
Minimal impact on air quality.and.fuel consumption. ~Noise impacts from speed humps
as described for that device.
Noise, Air ..
Quality,
Energy
Consumption
i Traffic
Safety,
Emergency
Response
Aesthetics
The effects on safety and emergency service, s depend on the mix of devices used (refer
to individual descriptions). A slow street may be acceptable on emergency response
routes if speed humps are not employed.
Impacts on aesthetics are the same as for the various devices used. The density of
measures used may result in a hea~y concentration of signs and striping which will
degrade aesthetics. Use of landscaped islands adds greenery where asphalt was
formerly present.
Maintenance Every traffic calming device requires maintenance. Refer to maintenance requirements
for the individual devices used.
Approximate The cost is the sum of costs for the various devices employed. Refer to costs for
Cost individual devicgs such as bulbouts, speed humps, speed tables, and median islands.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
16. TURN PROHIBITION SIGNS
M
16. TURN PROHIBITION SIGNS
The basic purpose of turn prohibition signs is to prohibit certain turns in order to improve safety or prevent
congestion on main streets. As used in neighborhood traffic calming, "No Right Turn" or "No Left Turn"
signs, with 0r without specified hours of the day, can be used to block or break up shortcutting traffic
patterns on residential streets. Since these are passive devices, their success depends on their general
acceptance by drivers and on police enforcement. Without enforcement, driver violation rates can be high.
Even with enforcement, violation rates are typically 20 percent, and generally leads to resident complaints.
Turn prohibition signs are an inexpensive way to achieve volume reductions similar to diverters, median
barriers and street closures, but driver violation and requests for enforcement are usually nagging problems.
Local examples: Churchill at Alma (Palo Alto), Willow Road between Middlefield and U.S. 101 (Menlo
Park).
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
Significant volume reduction is possible, up to about 70 percent. Potential large
undesired diversion of traffic to other nearby streets. Best used where this diversion is
to arterial or major collector streets.
If the movement being prohibited had formerly been used by a driver population as a
speedy through route, substantial reduction in the incidence of speeding is possible.
Speed of remaining traffic is not affected.
Noise reduction is proportional to volume reduction. Emissions and fuel consumption
will decrease on street where the restriction is .located, but could be offset by minor
increase due to detours of residential traffic in the nearby area.
Accident reduction is expected if the prohibited movement had been an accident
problem. No impacts on emergency services.
A single sign has an incremental negative aesthetic impact.
Maintenance for a single sign is minimal.
$150 per installation.
Limited experienc~ in Palo Alto suggests that regular Police enforcement must be
provide to prevent flagrant violation. Because such enforcement is usua!ly not
possible, this measure is usually not recommended for traffic calming purposes. If
channelization (raised islands) are used in conjunction with a turn prohibition sign,
compliance is increased, along with cost, reducing the need for Police enforcement.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
17. DIAGONAL D1VERTERS, FORCED CHANNELIZATION,
AND MEDIAN BARRIERS
Diagonal Diverters with Full Street Closures
Median Barrier
Park Blvd/Mead0w, Palo Alto
Median Barrier
Charleston/Louis, Palo Alto
17. DIAGONAL DIVERTERS, FORCED TURN CHANNELIZATION,
MEDIAN BARRIERS
Forced turn channelization refers to one or more raised traffic islands at intersection approaches or within
intersections, designed to force traffic to make or forego certain movements. There are numerous variations
of design and placement of islands depending on which movements are being allowed or prevented. A
diagonal diverter forces all traffic onto an intersecting street. These measures break up through routes,
making vehicle travel through a neighborhood difficult, while not actually preventing it. Thus, these
devices are more forgiving than street closures. The primary purpose of these measures is to reduce or
eliminate through traffic’movements.’Residents must. adopt a new-,driving.route to access the affected street.
Bicycle and pedestrian access is usually maintained. Similar restrictions in traffic movements may be
accomplished by regulatory signing only, but the raised islands provide a physical deterrence that signing
by itself cannot provide. Local examples in Palo Alto: Park Boulevard at Margarita Avenue, Bryant Street
at Embarcadero Road, E. Meadow Drive and Charleston Road at Park Boulevard, Charleston Road at Louis
Road.
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
Up to about 70% reduction possible, depending.on how many movements are
restricted. Potential large undesired diversion of traffic to other nearby streets. Best
used where this diversion is to arterial or major collector streets.
Reduces speeds in the vicinity of the device and may also reduce or eliminate the
driver population that had previously used the street as a speedy through route. Thus,
the incidence of speedin~ mar be reduced.
Reduces noise if volumes are reduced. Emissions and fuel consumption may decrease
on street where the device is located, but offset by minor increase due to detours of
residential traffic in the nearby area.
Reduces accident potential in the immediate vicinity, but may shift the potential to
other streets. If an opening in the closure provides emergency access with a raised
block in the center ("pan basher"), fire and paramedic vehicles will encounter minimal
delay but police vehicles will not be able to pass. If access requires the unlocking of a
removable bollard, delay will be substantial, and emergency drivers will usually use an
alternate route. A minimum width of 20 feet for two-way travel will be maintained. For
one-way sections (such as where a median splits the two travel directions), a minimum
width of 16 feet will be maintained for one-way travel .where the one-way sections are
longer than 30 feet. Where the one-way section is less than 30 feet long, a minimum
width often feet will be maintained for one-way travel. These widths are the minimum
required by the Fire Department for emergency access and by the Transportation
Division for normal traffic flow.
Islands may be landscaped, adding greenery where asphalt was formerly present.
Required signs and reflective devices may be unattractive.
Every traffic calming device requires maintenance. Automatic irrigation decreases the
need for landscaping maintenance and watering. Depending on the design, half!
closures may interfere with street sweeping and gutters may clog.
Costs will vary widely depending upon the size, number and location or raised islands.
For a diverter, a budget design (not attached to curb) is $12,000. High aesthetic/low
maintenance design (attached to curb): $40,000 (varies depending on new storm
drainage construction). Landscaped median barrier with automatic irrisation: $25,000.
Depending on the design, drivers may drive around the channelized area and make
illegal turns or U-turns. Drivers of high-clearance private vehicles may driver through
the pan-basher type of opening, generating resident complaints and need for occasional
enforcement. Parking spaces may be eliminated in the vicinity of these devices.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
18. ONE-WAY (HALF) STREET CLOSURES
Half-Street Closure
Park Blvd
Half-Street Closure
Park Blvd/Chestnut
Portland
18. ONE-WAY (HALF) STREET CLOSURES
A one-way closure is a closure to traffic in one direction only, while permitting two-way traffic on either
side. This closure is best installed to prohibit entry to a street segment, rather than to prohibit exit. Its
primary purpose is to eliminate shortcutting or through traffic in one direction on the street on which it is
installed. Access for emergency vehicles and bicycle and pedestrian access are maintained. Residents must
adopt a new driving route to access the affected street. Many of the characteristics of full street closures
apply to half-closures, but the latter are less extreme because they allow traffic flow in one direction. Half
street closures can take the form of a simple barricade or landscaped islands. Because they only block half
the street, they are easily violated~ ..thus .generatingxesident ,complaints. Local examples: Park Boulevard
north of College Avenue; Park Boulevard south of Lambert Avenue.
Traffic
Volume
Speed
Noise, Air
Quality,
Energy
Consumption
Traffic
Safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
Eliminates all but local residential access traffic in one direction on the street on which
it is installed. Potential large undesired diversions of traffic to other nearby streets.
Best used where this diversion is to arterial or major collector streets.
Does not reduce speeds, per se, but eliminates part of the driver population that
previously had used the street as a speedy through route. Thus, the incidence of
speedin~ mar be dramaticall), reduced
Due to reduced traffic volume on the street, noise and emissions are reduced on that
street. Emissions and fuel consumption may increase due to minor detours of
residential traffic.
Reduces accident potential in the immediate vicinity, but may shift the potential to
other streets. Emergency vehicle access is .not impaired, as drivers can enter the open
side of the street. For one-way sections, a minimum width of 16 feet will be
maintained for one-way travel where the one-way sections are longer than 30 feet.
Where the one-waYsection is less than 30 feet long, a minimum width of ten feet will
be maintained for one-way travel. These widths are the minimum required by the Fire
Department for emergency access and by the Transportation Division for normal
traffic flow.
Half closures may be landscaped, adding greenery where asphalt was formerly present.
Required signs and reflective devices may be unattractive.
Every traffic calming device requires maintenance. Automatic irrigation decreases the
need for landscaping maintenance and watering. Depending on the design, half
closures may interfere with street sweepin~ and gutters may clog.
Budget design (not attached to curbs): $6,000. High aesthetic/low maintenance design
(attached to curb): $20,000 (higher or lower depending on new storm drainage
construction).
Ease of driver violation (driving the wrong way around the half closure) may result in
resident complaints and may require Police Department enforcement Parking spaces
eliminated in half closure locations.
Appendix: Inventory of Neighborhood Traffic Calming Measures May 10,2000
19. FULL STREET CLOSURES
Palo Alto
Palo Alto
Palo Alto
Palo Alto
19. FULL STREET CLOSURE
A street closure is a complete closure of a street either at an intersection or midblock. Its primary purpose is
to eliminate shortcutting or through traffic On the local street on which it is installed. Ideally, through traffic
will be mostly rerouted to streets intended for that purpose (arterials and, to a lesser degree, collectors).
!Access for emergency vehicles can be p~’ovided across the closure. Bicycle and pedestrian access is
maintained. This is perhaps the most extreme traffic management measure in that it requires a complete
detour for all drivers. Residents must adopt a new driving route to access the affected street. Street closures
are discouraged by Policy T-33 of the City’s Comprehensive Plan ("Keep all neighborhood streets open
unless there is a demonstrated safety or overwhelming through traffic problem and there are no acceptable
alternatives, ’or unless ~’a closure ~wouid increase the~ use of.*alternative transportation modes.") .Street
closures are controversial because (i) unless carefully sited, they unbalance the traditional traffic street grid,
easily diverting large volumes of traffic onto other residential streets; and (ii) they impose significant
detours for local residents. Multiple street closures can create a cul-de-sac pattern similar to new suburban
subdivisions, except that access is retained for cyclists, pedestrians and emergency vehicles. Street closures
can take the form of a simple barricade, landscaped islands, a cul-de-sac, or a mini-park. Local examples in
Palo Alto: Evergreen Park and College Terrace neighborhoods, Bryant Street at Lowell and El Verano
Avenues, various locations along Embarcadero Road.
Traffic Eliminates all but local residefitial access traffic on the street on which it is installed.
Volume Potential large undesired diversion of traffic to other similar streets. Best used where
this diversion is to arterial or major collector streets.
Speed Does not reduce speeds, per se, but eliminates the driver population that previously had
used the street as a speedy through route. Thus, the incidence of speeding is
dramatically reduced.
Due to reduced traffic volume on the street, noise and emissions are reduced on that
street. Emissions and fuel consumption may increase due to minor detours of
residential traffic.
Noise, Air
Quality,
Energy
Consumption
Traffic
safety,
Emergency
Response
Aesthetics
Maintenance
Approximate
Cost
Other
Reduces accident potential in the immediate vicinity, but may shift the potential to
other streets. If an opening in the closure provides emergency access with a raised
block in the center ("pan basher"), f’u’e and paramedic vehicles will encounter minimal
delay but police vehicles will not be able to pass. If access requires the unlocking of a
removable bollard, delay will be substantial, and emergency drivers will usually use an
alternate route.
Closures may be landscaped, adding greenery where asphalt was formerly present.
Required signs and reflective devices may be unattractive.
Every traffic calming device requires maintenance. Automatic irrigation decreases the
need for landscaping maintenance and watering. Depending on the design, closures
may interfere with street sweeping.and gutters may clog.
Budget design (not attached to curbs): $12,000. High aesthetic/low maintenance design
(attached to curb): $40,000 (varies depending on new storm drainage construction).
Mini-park design: $100,000+
Closures with emergency vehicle openings created by a low concrete block ("pan
basher") may be violated by high clearance non-emergency vehicles, generating
resident complaints and need for occasional police enforcement. Parking spaces
eliminated in closure locations.
Appendix: Inventory of Neighborh.ood Traffic Calming Measures May 10,2000
DIRECTORY OF
TRAFFIC CALMING
WEB SI°I’iES
Compiled By: Bhavna Mist.ry
City of Palo Alto
Department of Plarming and Community Environment
Transportation Division
Joseph Kott, Chief Transportation Official
Ashok Aggarwal
Olubayo Elimisha
Rob Gill
Amanda Jones
Gayle Likens
Bhavna Mistry
. Carl Stoffel
Christopher Thnay
A Review of Current Traffic Calming Techniques By T. Harvey (HETS)
http://www.its.leeds.ac.uk/primavera/p calmiug.html#AR
Contents, Abstr.act, introduction, Background, Traffic Calming Techniques, Traffic calming
on links, Traffic calming at junctions, Gateways Traffic management measures, Traffic
calming on main roads, Effectiveness of Traffic Calming Measures, Speed reduction,
Accident reduction, Noise reduction, Air, pollution,-Public Consultation, The Cost of Traffic
Calming, Conclusions, References, Appendix A: Examples of Traffic Calming on Main
Roads. Appendix References
Canadian Guide to Neighborhood Traffic Calming
http://www.tac-atc.ca!pro~ams/caiming/~alming.htm
¯Chapter I provides an introduction to traffic calming, highlighting the key issues affecting
planning, design and implementation.
¯Chapter 2 describes how the community, elected officials and municipal staff can participate
in a meaningful and effective way in a traffic calming study.
¯Chapter 3 provides information and a process to assist in screening and selecting the most
appropriate measures to resolve a particular transportation problem. The chapter describes 25
different measures currently used by Canadian municipalities to calm traffic, which include
vertical deflection, horizontal deflection, obstruction and signing measures.
¯Chapter 4 provides detailed design guidelines for the 16 traffic calming measures carried
forward from Chapter 3. The chapter begins with a discussion of the general factors to be
considered in the design phase, including the implications of grades, long vehicles, surface
drainage, maintenance, materials, street-scaping, and temporary installations. The remainder
of the chapter provides detailed geometric, signing and pavement marking design guidelines.
Center for Transportation Research and Education
http://www.ctre.iastate.edu/research.htm
¯CTRE ensures that research will be oriented toward real-world results and applications by
structuring its research activities .around interdisciplinary and interorganizational teams.
CTRE staff conduct research in
¯Advanced Transportation Technologies: CTRE is a leader in the development and
evaluation of field operational tests of intelligent transportation systems (ITS) for commercial
vehicle operations (CVO).
¯Transportation Planning and Information Systems: CTRE is a leader in fusing data with
technology to create tools for transportation planning and problem solving, and specializes in
geographic information systems applications for transportation (GIS-T).
¯Portland Cement Concrete: The new Center for Portland Cement Concrete (PCC) Pavement
Technology will condtict training, technology transfer, and applied research on PCC
pavement design, construction, materials science, and maintenance.
Citizens Alliance for Livable Municipalities, Wakefield Chapter
http:/!ou~vorld.compuserve.com/holnepa~es/kbarrett/cahnwake.htm
¯Improving the quality of life through formation of a safer, community-enriching and
environmentally friendly transportation system
¯How to Start a Traffic Calming Group in Your Town
¯A group of concerned Wakefield Massachusetts citizens working to preserve and restore the
peacefulness, vitality, attractiveness, and safety of our community, which is threatened by
excessive speed and volume of automobile traffic.
¯Advocate for: traffic calming for slower, safer speeds, reducing the volume of traffic and
demand for parking,, improving conditions for walking and bicycling.
¯Issues and Potential Projects
¯Send email to CALM Wakefield (74650.120@compuserve.corn)
City of Albuquerque, New Mexico
Neighborhood Traffic Management Program
http:/Avww.cabq.gov/streets~ntmp.html
¯City Involvement, Policies, Objectives, Types of Projects : (1) Local Street Improvement
Projects, (2) Neighborhood Area Studies, (3) Collector Speed Control Projects
City of Austin, Texas
Transportation Department
http://www.ci.austin.tx.us/roadworks/
City of Bellevue, Washington
http://204.236.15.221/transportation/traffic/neighbor.htm
¯Department Overview, Current Projects, ROW Permits, Bicyling in Bellevue, Useful Links,
Programs, Construction Updates, Find Your Bus Route, FAQs, View Current Bellevue
Traffic, Plans and Studies, Downtown Access Project
City of Berkeley, California
Public Works Department
http:/!www.ci.berkele¥.ca.us/pw/traffic/traffic.html
¯Traffic: Design Features, Traffic Calming Devices
¯Parking: Parking Restrictions, Parking Requirements - Plan, Residential Permit
¯Parking Program
¯Other: Speed Limit, Block Party Activity
¯Traffic Volume Counts
¯Map
¯Truck Routes
City of Boulder, Colorado
Neighborhood Traffic Mitigation Program
http://www.ci.boulder.co.us/publicworks/depts/tr7.htn~l
¯Your Neighborhood Traffic Mitigation Program
¯About the NTMP - General Information
¯Background Information
¯NTMP Educational Resources
¯Enforcement - Photo Radar And Photo Red Light Information
¯Traffic Mitigation Device Explanations & Evaluations
¯Traffic Mitigation Device Locations
City of Broken Arrow, Oklahoma
Traffic Calming Program
http://www.citv.broken-arrow.ok.us/trafcalm.htm
City of Buffalo, New york
Neighborhood Traffic Calming
http://www.bu finet.net/-allemand/TC.html
City of Cambridge, Massachusetts
Cambridge Traffic Calming Program
http~//cambridgema.ab~ut.c~m/~ca~/neweng~andus/cambridgema/gi/dynamic(~ffsite.htm?site=http
://www.ci.cambridge.ma.us/%TECDD/envirotrans/trafcalm/
¯The goal of traffic calming projects
¯Current and Previous Projects
¯Bibliography of Traffic Calming works
City of Cupertino, California
Neighborhood Traffic Management
http://www.cupertino.org/traffic/NTM.html
Neighborhood traffic management is a high priority goal for the Cupertino City Council. We
want to have livable neighborhoods that are free from traffic impacts. Staff is available to help
neighborhoods to resolve their traffic concerns in a public review process.
Traffic calming goals
Traffic calming objectives
City of Fairfax, Virginia.
http://www.ci.fairfax.va.us/ci _tyinfo/traffic.html
¯Policy For Use Of Traffic Calming On City Streets - City of Fairfax, Virginia
¯Installation of Residential Traffic Calming (RTC) Devices
¯Residential Traffic Calming Devices
City of Fort Worth, Texas
Department of Public Works
Speed Humps Project
http://~i.fort-worth.tx.us/fortworth/tpw/SpeedHumpPilot2.htm
City of Houston, Texas
Department of Public Works and Engineering
http:/!www.ci.houston.tx.us/departme/works/
¯Speed Hump Policies and Procedures
City of Las Vegas, Nevada
Department of Transportation
Speed Humps
http://www.c Llas-vegas.nv.us/speed~ bumps.htln
City of Missoula, Montana
Traffic Calming Program
http://wwwrci.missoula.mt.us/publicworks/calming.htm
City of New York, New York
http://www.ci.n¥c.n¥.us/html/dotlhtml/aboutdot/faqs.html#Slowin.~ Down Traffic
FAQ: Slowing Down Traffic: Traffic Calming Information
Q: What is the difference between a speed hump and a speed bump?
Q: How can I get a speed hump installed on my block?
Q: How can I have a mid-block crosswalk installed on my street?
City of Portland, Oregon
Traffic Calming Program
http J/www.trans.ci.portland.or.us/Yraffic Management/trafficcalming/
¯How it Works
¯Traffic Calming Devices
¯Portland Project Evaluations
¯Traffic Calming and the Law
¯Current and Future Projects
¯New Traffic Calming Research
¯Studies and Reports
¯Traffic Calming Calendar
¯Program Info and Staff
City of Salem, Oregon
Strategies For Citizen Involvement In Traffic Issues
http://ww~v.open.or~-scserv/neighbor/h6traffc.htm
¯Introduction, Remembering the Big Picture, Preliminary Contact with Traffic Staff, Make the
Appropriate Contacts, Know the Key Players in the System, Gather Your Information,
Presenting Your Case at Meetings, Conclusion
City of San Buenaventura, California
Neighborhood Traffic Management and Calming Program
http://www.ci.ventura.ca.us/meet/depts/traffic/Traffic Calmin~ Pro~ram/Program.html
¯Traffic Calming for Livable Neighborhoods
¯Neighborhood Traffic Management Options
¯Current City Practices
¯Proposed Neighborhood Traffic Management Process
¯Effectiveness of Traffic Calming Devices
¯Effect on emergency Vehicles.Response Time
¯Traffic Diversion
¯Impacts to Transit and Utility Vehicles
¯Consideration for Other Roadway Uses
¯Noise Impacts
¯Loss of Parking
¯Liability Exposure Implications
¯Visual Impacts and Aesthetic Concerns
¯Increased Maintenance Costs
City of San Francisco, California
Strategic Analysis Report on Traffic Calming - Initiated by Commissioner Leslie Katz
http://www.ci.sf.ca.us/sfia/final.htm
City of Tempe, Arizona
Traffic Management Program
http://www.tempe.gov/traffic/trafingnt.litm
¯This plan has the goals, policies, guidelir~es for placing traffic calming devices in the city.
Speed Hump Request Flow Chart
Requests Procedui
City of Toronto, Ontario Canada
Installation of Speed Humps on City Streets - Policy Report, August 1997
http://old.ci _t3,.toronto.on.ca/4service/spdhmp.htm
"Do speed humps work? Study says they divert traffic to parallel streets"
By: Andrew D. Beadle, Staff Writer
http://www.gazette.net!archives/199806/news/coun _t3,/sto _ry007.html
Federal Highway Administration
Flexible Design/Traffic Calming
http:/!www.fh wa.dot.gov/environm ent/calming2.htm
To help meet that challenge, the FHWA has prepared a guide, "Flexibility in Highway,
Design", for the purpose of provoking innovative thinking for fully considering the
community values and scenic, historic, aesthetic, and other cultural values, along with the
safety and mobility needs of our highway transportation system. The Guide does not establish
any new or different geometric design standards or criteria for highways and streets in scenic,
historic, or otherwise environmentally or culturally sensitive areas, nor does it imply that
safety and mobility are less important design considerations. Instead, it should be used as a
companion to the AASHTO "Green Book" helping highway project managers accommodate
these various arfd often conflicting values when solving transportation needs.
Fehr & Peers Associates. Inc - Transportation Consultants
http:!/www.fehrandpeers.com/
¯Your comPlete guide to traffic calming and neighborhood traffic management, and how they
can be used to reduce speeds, reduce traffic volumes, and improve safety in residential
neighborhoods.
This informational traffic calming site is provided as a pubic service to city and county publicworks officials, residents, motorists, and anyone else interested in f’mding out about traffic
calming: what it is, where it has been one, .how well it works, etc.
How is Fehr & Peers Associates involved in Traffic Calming? The information on this site is
drawn primarily from Traffic Calming State of Practice, by Reid Ewing, written for the
Institute of Transportation Engineers with funding from the Federal Highway Administration.
Institute of Transportation Engineers
http://www.ite.org/traffic/index.httn
Calming Measures, Library, Seminar Materials, Events, Selected Materia!s, Discussions,
Other Links
The following are cities or counties that have reported experience~ with traffic calming, but do not have
any traffic calming information on their Web sites:
Annapolis, MD, USA; Anne Arundel County, MD, USA; Asheville, NC; Boca Raton, FL, USA; Brea, CA,
USA; Bridgeport, CT, USA; Broward County, FL, USA; Chicago, IL, USA; Chico, CA, USA; Collier
County, FL, USA; Columbus, OH, USA; Carrborro, NC, USA; Costa Mesa, CA, USA; Cypress, CA, USA;
Dallas, TX, USA; Dayton, OH, USA; Decatur, IL, USA; Edmonds; WA, USA; El Monte, CA, USA; E1
Paso, TX, USA; Fort Lauderdale, FL, USA; Fort Worth, TX, USA; Fresno, CA, USA; Gainesviile, FL,
USA; Germantown, TN,USA; Gwinnett County, GA, USA; Hartford, CT, USA; Hawthorne, CA, USA;
Hilton Head Island, SC, USA; Kitchner, Ontario, Canada; La Mesa, CA, USA; Little Rock, AR, USA;
Long Beach, CA, USA; Los Angeles, CA, USA; Menlo Park, CA, USA; Merced, CA, USA; Moscow, ID,
USA; Nepean, Ontario, Canada; New Orleans, LA, USA; Oakland, CA, USA; Ojai, CA, USA; Orange
County, CA, USA; Orinda, CA, USA; Palm Beach County, FL, USA; Palm Desert, CA, USA; Pasadena,
CA, USA; Phoenix, AZ, USA; Portland, ME, USA; Poway, CA, USA; Prince William County, VA, USA;
Raleigh,NC, USA; Raytown, MO,’USA; San Bernardino, CA, USA; San Diego;CA, USA; San Jose, CA,
USA; San Leandro, CA, USA; Scottsdale, AZ, USA; Seminole County, FL, USA; Tallahassee, FL, USA;
Thornton, CO, USA; Troy, MI, USA; Upland, CA, USA; Upper Arlington, OH, USA; West Palm Beach,
FL, USA
Linden Hills Neighborhood - Traffic Calming and Bicycle Plan
http://freenet.msp.mn.us/ip/nhoods/mpls/linden/transtop.htm
¯Part I: PurpoSe and Background Information - pages 1-13.
¯Part II: Problems, Neighborhood-Suggested Solutions & Staff Recommendations: pages 14-41
Montgomery County, Maryland
Maryland Department of Public Works and Transportation
Residential Traffic Calming Program
http://www.dpwt.com/TraffPkgDiv.htm
Speeding and unsafe driving practices on residential streets have become increasing concern
to County residents and to the government agencies charged with ensuring traffic safety.
Excessive speeds jeopardize both the safety and "liveabi!ity" of our neighborhoods. The
Department of Public Works and Transportation (DPWT) and the Department of Police have
cooperatively implemented a comprehensive residential speed control program which enlists
community residents in helping to solve the speeding problem .and improve the residential
environment. The program includes the three components necessary to successfully reduce
speeding: education, engineering and enforcement.
DPWT and the police provide traffic safety services for over 1600 miles of residential streets.
In order to provide the most effective service for these streets given resources, we have
developed a triage system for addressing excessive speed on residential streets: Low Volume:
Local Traffic Streets, Moderate Volume: Collector Streets, Higher Volume: Collector Streets.
Neighborhood Traffic Calming Program For Residential streets
Town of Brookline, Massachusetts, September 1995 Author: Nancy Sabol Conger
This document was part of a Community Service Fellowship which studied the concept of
Traffic Calming as initiated by the Salisbury Road/Corey Farm Neighborhood Association.
The fellowship was funded by the Harvard University Graduate School of Design, The Town
of Brookline Public Works Department, the Salisbury Road/Corey Farm Neighborhood
Association (SRCFNA) and the Brookline Community Fund.
TLCNET: The Transportation for Livable Communities Network
http://www.tlcnetwork.or~resource.html
On-line resources:
Institute of Transportation Engineers, American Association of State Highway and
Transportation Officials*, Bicycle Federation of America]Bicycle and Pedestrian
Clearinghouse Surface Transportation Policy Project*, Train Riders Northeast Transportation
Alternatives (Greater New York City bicycle and pedestrian advocates) Flora Community
Web Site Metro Magazine’s Transit Center National Trust for Historic Preservation
Transportation Research Board U.S. Department of Transportation*, Cars and Their
Environmental Impact Federal Transit Administration American Public Transit Association
Local Government Commission/Center for Livable Communities Sustainable Com~munities
Network LUTRAQ (1000 Friends of Oregon’s Land Use, Transportation, Air Q~~iity Project)
Pedestrian Network*, Congress for the New Urbanism City of Portland Traffic Calming
Information Site
¯Email Listserv
¯New and Commentary on Transportation
¯Community Bulletins
Traditional Neighborhood Development
Traffic Calling Toolkit
http://unix.worldpath.net~-chellman/tct.htmi
Traffic Calming - A Report By: Kris Jacobson
http://www.netaccess.on.ca/-jacobson/calming.html
Traffic Calming in Australia, Canada, and Europe
http://www.usroads.com/iournals/p/rilj/9801/ri980105.htm
Traffic calming truly has become an issue of international significance, tt has been a focus of
debate in the United States, Australia, Canada, and many European countries. Transportation
professionals from several countries discussed their approach to traffic calming in the July
1997 issue of the I~E Journal.
TRANSPEED
Transportation Partnership in Engineering Education Development
Traffic Calming - Techniques and Management
http://www.en gr.washin gton.~du/-uw-epp/Transpeed/trc html
Web cams of Traffic Sites
http://www.looksmart.com/eus I/eus53832/eus62416/eus328828/eus 142577/eus277666/eus290108
/r?l&izl&pin=991228x5c2be87663f4bd0baal &