Get documents about "Neighborhood Traffic ManagementProcess and Results
Shared by: tcu11291
Categories
Tags
traffic calming, neighborhood traffic management, traffic management, city council, speed humps, city staff, traffic management program, management strategies, congestion management, mitigation measures, neighborhood streets, neighborhood association, the neighborhood, management process, residential streets
-
Stats
- views:
- 1
- posted:
- 5/14/2010
- language:
- English
- pages:
- 7
Document Sample
Neighborhood Traffic Management:
Process and Results
Patricia B. Noyes
William C. Fox, P.E.
Overview residents that they don’t have a traffic
Neighborhood traffic management, also problem in their neighborhood if they believe
known as traffic calming or traffic mitigation, one exists. Therefore, the planning and
has become a major focus in local public involvement process is a critical, if not
government and the traffic engineering the most critical, aspect of neighborhood
profession. As the use of the automobile traffic management.
continues to increase, so does the outcry to
minimize its impact on residential streets. Define the problem
Cities of all sizes have focused on managing Traffic calming is a term used to address a
traffic in residential areas for a number of range of problems with an even wider range
years, but the issue is getting increasing of solutions. These include the speed and
attention and scrutiny. The common goal is volume of traffic; traffic safety; pedestrian
to “calm traffic,” with a specific focus on and bicycle safety cut-through traffic in
residential areas. Although there is general neighborhoods; traffic noise impacts and
agreement among transportation other quality of life concerns associated with
professionals about the tools used to calm traffic. Therefore, it is essential to define
traffic, there is not always clear agreement which specific issues exist in each
on the process for selecting and neighborhood or area of the city before
implementing the tools or on the use and appropriate solutions can be demonstrated or
effectiveness of various devices. implemented. Because there are so many
traffic calming tools in the “toolbox,” each
This paper focuses on the planning process, with its own set of advantages,
approaches to working with local residents, disadvantages and results, the decision to use
implementation considerations, and the a specific traffic calming technique should be
actual effectiveness of various tools. made based on a clear definition of the
problem. Without a clear understanding of
The Process the problem traffic calming devices can
The process used to develop a neighborhood create more disruption and more problems
traffic management plan is ofien more than they are intended to solve.
important than the specifics of the plan itself.
Traffic management problems are, in large Defining the problem is not a simple issue of
part, citizen perception. In no way does this data collection and professional judgment. It
mean they are any less significant than those requires sharing hard data, anecdotal data
that are clearly documented, it only means and perceptions in an open dialogue among
that the selection of tools and the measures city staff, residents of the neighborhood,
of success need to incorporate their affected travelers and any others with an
perceptions. No amount of traffic interest. Because traffic management
engineering data will convince neighborhood addresses various quality of life issues,
perceptions of the problem and of the If neighborhood traffic calming is to be
effectiveness of the solutions are as valuable, successful, it must address the unique set of
and in some cases more valuable, than hard concerns within each neighborhood.
engineering data. The rush to judgment in Neighborhood plans should be developed
defining the problem is often the main source that provide a comprehensive approach for
of failure of traffic calming efforts. the neighborhood, focus on the specific
problems defined for the neighborhood, and
Planning approach minimize the negative impacts. This requires
There are a number of ways to address a systematic public outreach and involvement
traffic issues in residential areas. In some process on a neighborhood-by-neighborhood
cases, it is most appropriate to respond basis to develop a shared definition of the
quickly and directly to a speciilc traffic problems to be solved and appropriate traffic
concern. This applies to site-specific safety control measures. The bottom line is, fit
concerns that can be addressed with simple doesn ‘t work for the residents, it won ‘t work
signing or operational changes. This is for the City, and all of the effort expended to
usually not a good approach to address develop a solution will have been wasted.
traffic calming concerns such as traffic speed
or cut-through traffic, as these concerns Develop the range of solutions
generally occur over a larger area and site To develop an effective toolbox of traffic
speciilc techniques may simply move the management devices there must be a
problem cause different problems, or be common understanding of the advantages,
labeled as ineffective by concerned residents disadvantages, limitations, and appropriate
who raised the issues in the first place. applications of each device. This requires an
education process on the part of all involved
The recommended approach for and the development of guidelines for the
neighborhood traffic management is a more use of each device. Some devices work well
comprehensive neighborhood planning under certain circumstances while creating
process. The advantages to this approach problems, without the desired results, under
include consistency in addressing traffic others. It is important that the appropriate
issues throughout the city; greater application of each device be defined and
involvement of the neighborhood in the guidelines developed. Agencies must review
planning process; solutions better suited to each possible tool to determine its
the unique problems experienced by the appropriateness for use by the agency before
residents; ownership of the solutions by the the discussion is brought to the public. A
residents who will be most impacted; and staff workshop to review the appropriateness
reduced impacts to parallel streets or other of specific calming tools is recommended.
neighborhoods. The major disadvantage is With staff support in place for the toolbox,
that a comprehensive neighborhood planning the public plan development process will be
effort requires more resources in terms of most effective.
staff and resident time, and the overall cost
of the process and improvements. The costs, Sample tool evaluation
however, are often well worth the investment Given the number and range of traffic
to find the best set of solutions to implement management tools, it is important to consider
which does not result in unanticipated each tool very carefidly before including it in
secondary problems. the toolbox. For example, let’s consider the
applications, advantages, disadvantages, Policy considerations
limitations and other impacts of neckdowns, There are several significant policy
or curb-extensions. considerations in developing a
comprehensive traffic management plan.
Neckdowns are used to physically and These include finding, prioritization and
visually narrow the street at an intersection system impacts.
or at mid-block locations. They are the
actual realignment and reconstruction of the Funding and Priorities
curb to bring the curbline into the roadway. Funding is an important part of the planning
They can be used on streets that are wide and implementation of traffic calming
enough to accommodate on-street parking. measures. In new developments where
The realigned curb is generally parallel to the traffic cahning can be designed into the plan,
on-street parking lanes. Neckdowns are the cost of traffic calming should be
used where traffic speed and pedestrian incorporated into the cost of development.
safety are a concern. They provide shorter However, in previously developed areas that
crossing distances for pedestrians at require retrofitting devices, the tiding of
intersections and, if landscaped, they provide these improvements becomes a much more
a visually narrowing effect and improved complex issue. The cost of the
aesthetics. improvements is often higher than a new
installation due to necessary changes in street
However, neckdowns may create drainage and other roadway
impediments to bicyclists and reduce the reconfiguration.
turning radius at intersections if not designed
carefi.dly. These impacts should be The question of who pays is one that should
considered for streets serving as a bicycle, be addressed in a public forum. Unless the
truck or emergency route. Some other City has adequate finding to install all traffic
limitations on the use of neckdowns include calming devices citywide within a short time
the cost of realigning the intersection or period, prioritization of neighborhoods is
street and potential issues with storm necessary. When finds are limited, one
drainage. Used by themselves, neckdowns option is to consider incremental
may not achieve the desired traffic calming improvements, starting with less expensive
effect. techniques, testing the results and adding
new tools as necessary. These issues need to
Neckdowns area fairly expensive option that be addressed on a citywide basis to ensure a
provides aesthetic and pedestrian safety level of equity throughout the city.
benefits, They are best used as part of
neighborhood-wide strategy, in conjunction Residents need to be involved in the finding
with other tools such as medians, traffic discussions from the beginning of the traffic
circles or raised pedestrian crossings. They calming process. Some cities approach
are generally well received by residents and neighborhood traffic calming on a 50/50 cost
create minimal user and emergency service sharing with local residents. The residents
impacts if appropriately designed. themselves should be involved in the
definition of who is responsible for the local
cost sharing to ensure that the cost is
distributed equitably.
Impacts Policies regarding the allocation of both
As well as their intended positive impacts on positive and negative impacts must be a part
neighborhood traffic, calming techniques of the planning process to give clear
have potentially negative impacts as well. guidance on the agency’s priorities for
Some of these include impacts on emergency various concerns. These should include
response, impacts to facility users, ongoing impacts to residents as well as various
costs, and negative impacts to the services within the agency.
neighborhood residents. Resident impacts
may include financial costs, noise associated Demonstration and evaluation
with certain traffic calming devices, access Demonstration projects with comprehensive
limitations, visual impacts from increased evaluation of effectiveness are extremely
signs, and general nuisance impacts. Impacts important in initiating new traffic
to other users include potential increases in management plans. Demonstration projects
emergency response times and inconvenience should be undertaken in both new
created by various devices. developments and existing neighborhoods
requiring retrofit solutions. The evaluation
Impacts on emergency response is an process must include hard data, anecdotal
important consideration. Tests conducted by data, and resident and driver perceptions.
several fire departments have determined a
range of delays to fire trucks induced by Traffic calming effectiveness cannot be
traffic circles and speed humps. The results boiled down to the change in 85th percentile
of these studies are shown in Table 1, below. speed or number of accidents. It is more
Although the impact of any one device may elusive and qualitative, and measures should
not be significant, a series or system of include all aspects of the original problem
devices may add significant delay to definition for evaluation. Measures of
emergency response routes. resident satisfaction need to be developed
and documented when evaluating the
Device Boulder, CO Portland, OR Austin, TX effectiveness of a traffic calming plan.
I Traffic I 7.5to 10 I 1.3 to 10.7 I NA
Circle seconds seconds
Speed 2.8 to 4.7 0 to 9.4 1.8 to 9.8 The Results
Hump sewnds sewnds sewnds Issues of implementation and the
Table 1: Emergency Response Delay effectiveness of dillerent traffic calming
techniques are also important considerations
The use of certain devices can also create in addressing neighborhood traffic concerns.
traffic diversion to parallel routes. Dii%erent tools address difherent needs.
Sometimes the shill is desirable, such as Some are well suited for reducing traffic
when the receiving street is an arterial speeds, while others mitigate cut-through
roadway. But sometimes, if the plan is not traffic and volume. Some measures have the
developed carefidly, the traffic shifl may added benefit of being an attractive,
impact another local street or neighborhood. landscaped amenity to the neighborhood.
A policy should be developed ahead of time
to address how to deal with undesirable As various devices are implemented and
traffic shifts. evaluated, more data are available on
implementation concerns and how the
devices actually affect traffic in the
neighborhoods. The data below are fi-om typically reduce the average speeds by 2 to 6
recent studies conducted on various traffic mph.
management devices implemented on both
trial and permanent bases. Recent testing in Boulder of experimented
traffic circles on collector roadways with
Effectiveness of traftlc calming devices over 10,000 vehicles per day indicates that
Recent studies of permanent and trial average speeds are reduced by up to 8 mph
installations conducted in a few Colorado when measured halfivay between two circles.
communities offer encouragement on the use In one case, the percentage of motorists
of various traffic calming devices. The City exceeding the posted speed limit was
of Golden found that speed humps used in reduced from over 90 percent to fess than 40
series resulted in a 13 to 15 mph reduction in percent, as illustrated on Figure 1.
the 85th percentile speed and at least a 14
mph reduction in the maximum speed All-way stop signs have been less effective at
observed. Despite these impressive results, reducing travel speeds. Recent tests of
the speed humps were unpopular with the speeds in Boulder one-half block from all-
local residents. The humps were removed way stop control indicated that average
and were replaced with a combination of speed changes ranged from a 1 mph decrease
median islands, curb extensions, and a traffic to a 4 mph increase as compared to the
circle, all of which were attractively “before” condition.
landscaped. These landscaped features were
not quite as effective in reducing the 85th San Leandro, California conducted tests on
percentile speeds (9 to 12 mph reduction) speed humps and traffic circles. The speed
but were actually more effective in reducing hump tests found an average 9 mph
the highest speeds observed. The final result reduction in speeds, practically eliminating
is a much more livable roadway and a all speeds above 35 mph. They also found
neighborhood that is pleased. that the speed humps did not divert traffic to
the parallel streets.
The City of Thornton, Colorado recently
reported reducing 85th percentile speeds by San Leandro’s tests of traffic circles showed
5 mph through the use of a mobile speed a reduction of speeds from 34 mph to 26
trailer. Based on these encouraging results, mph, and average 8 mph reduction. In all
the City is considering expanding the cases, the speed reduction is higher when
program. measured close to the traffic calming device.
The City of Boulder, Colorado has been When considering the effectiveness of traffic
experimenting with traffic calming measures calming measures, it is important to consider
for quite some time and has employed speed that neighborhood resident satisfaction is just
humps, raised pedestrian crossings, flat top as important as hard speed and volume data,
speed tables, traffic circles, all-way stops, but is much harder to measure. Local
medians, neighborhood entry islands, residents perceive the benefits of slower
diverters, semi-diverters, turn restrictions, moving traffic through their neighborhoods
realigned intersections, and raised in ways that are diilicult to measure. Quality
intersections. Boulder’s speed humps of life increases are often lost in a typical
“after study.” Additionally, motorists
TRAFFIC CIRCLE SPEED REDUCTION TESTING
6000
50 100%
u Before Traffic Circle 1
7
I s W ith Traffic Circle I
45 90$6
5000
40 1 00%
4000 35 70%
30 60%
li
3000
~25- 50%
d
=20- 40$6
2000
15 30%
10 20% 4
i 000
5- fo%
0 0 + 0%
Daily Avg. Mml 95th %
Traffic Spead P.rcenlSe ParcentSe Speading
Volume (mph) Speed Speed
[mph)
(mph) FIGURE 1
traveling cross-town on a roadway that has their mobility has been critically impaired
been “calmed” will often express the without their input, it can become an
perspective that their mobility on the public emotional public debate, oflen in front of
roadway has been impaired for the benefit of a city council or in the local press, where
a few local residents. Surveys of resident images of children being hit by cars are
and user satisfaction should be considered. pitted against people dying in burning
Without documented information on citizen buildings or medical emergencies.
satisfaction, the measure of effectiveness
may be reduced to which interest group . Residents need to have a clear
screams loudest at public hearings or is most understanding of what the traffic calming
often published in the letters to the editor of measures will look like in their
the local newspaper. neighborhood before the contractor
shows up. The use of photographic
Implementation considerations examples of similar installations and/or
When preparing a traffic calming plan, there landscape architectural renderings of the
are a number of considerations that may proposed streetscape are vital to ensuring
affect the successful implementation of the that residents are not surprised at the
project. As noted above, a thorough public time of implementation. Similarly,
process with interested stakeholders is residents need to have a clear
critical. Specific planning and design issues understanding of the traffic control signs
that should be carefidly addressed include: that will need to be added to support the
selected devices. Signs are often viewed
. Emergency response agencies must be as a visual intrusion in the neighborhood
involved in the plan development. If if their need is not understood.
emergency response agencies believe
. Test installations are less attractive, and carefully planned and implemented so
in some cases less effective, than final that it does not become a safety hazard.
installations. In a test case, green Particular attention should be paid to the
landscaping is often substituted by sight distance needs of pedestrians and
something that either is made of concrete motorists using the local transportation
or painted some shade of orange or system. Low shrubs and deciduous trees
yellow. Test installations are important with limbs trimmed up above six feet can
in many cases, but extra communication be used near intersections and pedestrian
efforts are needed ahead of time to help crossings without compromising safety
local residents and political leaders of the traveling public.
endure the “ugly stage” of the test.
It is important to keep in mind that the
. The implementation of vertical traffic success of the traffic calming project often
calming measures (humps, raised depends on the system of devices that it
crossings, raised intersections, etc.) includes. Any one device would not likely be
needs to be carefidly designed and effective in solving a traffic calming need.
carefidly constructed to insure that the However, a system that includes a number of
device meets the desired speed reduction devices and types of devices that are
goal. A constructed device that is too carefidly spaced in the neighborhood has a
aggressive or too mild will not achieve high probability for success, both fi-om the
the goals of the project and will discredit perspective of measured engineering data
the entire traffic calming program. and improved quality of life for the residents.
. The implementation of horizontal traffic
calming measures (medians, traffic
circles, curb extensions and neckdowns, Patricia B. Noyes, Member
etc.) also needs to be carefhlly designed Pat Noyes & Associates
and constructed. Drainage issues need to 1566 County Road 83
be addressed before the pond develops, Boulder, CO 80302
and truck and service vehicle traffic (303) 440-8171
needs to be carefidly accounted for so
that service can be provided and trucks William C. Fox, Member
are not rerouted to other neighborhood TransPlan Associates
streets. 1375 Walnut Street, Suite 211
Boulder, CO 80302
. The combination and spacing of traffic (303) 442-3130
calming measures is critical to their
successful implementation. Each
neighborhood is unique and the local
considerations must be addressed when
preparing the plan.
. Landscaping of the traffic calming
measures often becomes an amenity to
the local streetscape, but it needs to be
