(2005) Conversations About Traffic Calming

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Conversations About Traffic Calming A Review of current Papers and Discussions

December 2005 UIC Prepared for Kazuya Kawamura By Mary Kaufman

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Table of Contents

Executive Summary Traffic Calming Naperville’s 3 E Program Residential Streets On-street parking Additional Designated Lanes

Intersection Geometrics

Roundabouts Impacts on Emergency Vehicles

Roadside Treatments Alternative Traffic Calming Strategies Lighting Appendix

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Executive Summary

The purpose of traffic calming is to

reduce collision frequency and severity,

increasing the safety and the perception of safety for non-motorized users of the

street,

reducing the need for police enforcement,

enhancing the street environment

increasing access for all modes of transportation, and

reducing cut-through motor vehicle traffic studies in Seattle, for instance, have shown

dramatic reductions in motor vehicle crashes after traffic calming.1

1 Lockwood, Ian. ITE Traffic Calming Definition. ITE Journal, July 1997

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Traffic Calming: an introduction Culd-de-sacs, although sadly popular in DuPage County, have very negative impacts

in terms of increasing congestion on local collectors and arterials. Culd-de-sacs are

directly responsible for difficulty in routing by Pace Suburban Bus Company. Further,

emergency response times increase because of increased traffic congestion on arterials

then might ordinarily occur on an open grid system. In some cases, direct routing can be

very difficult for emergency and transit vehicles.

Calm streets do not happen by accident. Curbing speeding and aggressive driving

behavior has to be a priority of the community, the planners, the engineers, the elected

officials and the police department. The coordinated efforts of public compliance,

through education, enforcement and good design, will solve the problem of calming

traffic.

Often, the municipality can further more than just the goal of traffic calming.

Sometimes a conversion in terms of lanes, parking or even pedestrian facilities more than

pay for the effort and materials involved by allowing for more public spaces, faster mass

transit and multimodal choices. This can add to the vitality and richness of a

neighborhood and retail district and keep home values from depreciating.

Civil engineering solutions that impede traffic such as Chicanes, Bulbs, etc. should be

used as a last resort. It is the most expensive of all the alternatives of traffic calming and

may have mixed results when not accompanied by public education and good will.

Further, it will increase emergency response times but depending on the device used, this

may be a relatively small trade off involving only seconds.

Generally geometric changes to a road is needed when

The traffic is out of character with the context of the road.

The traffic is not strictly local in nature.

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In both cases, education is not going to do it alone as the drivers are outside of the range

of the outreach capabilities of the municipality and further, if the roadway enhances

negative driving behavior, this must be remedied by correcting the design.

This reference hopes through discussions by engineers and planners and highlighting

research in traffic calming to give ideas to those who are trying to solve speeding in their

own communities.

Naperville’s 3 E Program

Brent Coulter P.E. of Coulter Transportation Inc., and Steve Cope, P.E. of

Naperville's Public works were the guest speakers featured for the 2004 DuPage Mayors

and Managers meeting. The subject of their presentations was to address the county's

concern over the increased speeding problems in the suburbs and talk about solutions that

had been found effective in some of the suburban communities. Featured predominantly

was the Naperville's Three E Program.

Brent Coulter, of Coulter Transportation, Inc. and Cemcon, Ltd.

“I’m a proponent of the 3 to 4 E process when alerted to a traffic calming problem and

am also putting together an online database for the traffic calming measures in North East

Illinois. Traveling in your car starts out like a football game with a game plan and trying

to move the ball around traffic, doing an end run around a block and shouldering your

way through, but as you near home, suddenly the game of baseball comes into play where

the goal is to reach home safely. And this is the objective we are trying to address.

The object of the current study is to help separate the emotion of irate stakeholders,

frustrated politicians and law enforcement from fact and to separate the real from the

perceived. Two things we have learned,

Selective speed enforcement works

Stops signs don’t work

So we have drawn from the Europe experience with physical barriers to some extent,

traffic circles, speed humps, tables and so on. The definition of traffic calming from ITE

usually involves physical alterations to the roadways. But for some roadways, especially

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local collectors restricting traffic flow is not something one wants to do right away. The

processes that get ignored are ITS, education and enforcement.

The 3 to 4 E process is as follows

Education

Enforcement

Engineering

*Expectancy, which ties to education*.

Expectancy is important because communities need to understand what is and isn’t

possible in terms of policy and engineering. It is realistic to eliminate the high end of the

speeding curve, but not realistic to eliminate ALL speeding.

First, selective speed enforcement does work according to most surveys that have been

conducted. However, the survey also shows that police departments are way too thin to

adequately cover the problems. One good solution seems to be the use of speed trailers

strategically placed and when combined with enforcement is very, very effective.

Enforcement needs to be done on a regular basis until people are conditioned that a

specific “problem” corridor is a “speed trap.”

Most departments are using speed trailers but they would be more effective if police

and public works did better communication and coordination. Specifically for the

purpose of collecting before and after data on things tried for speeding.

Steve Cope: Naperville Public Works: Traffic and Safety Engineer “The goals of my department is to make the community livable, aesthetically pleasing,

safe and functional for the residents,” said Steve. “I use the four E principles

emphasizing education and teamwork with neighborhoods in our community.”

The Process that Naperville uses is the following.

A resident calls to complain

That mobilizes public works to explain the program to them and offer to send

more information. If there seems to be more of an interest or a bigger problem

than just an educational one, they offer to send out an application to have the

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situation assessed by our department. 10 residents in the effected area must sign

the application

Public works goes to meet them.

Once the application has been turned in with the required signatures, the

Three-E team goes out to meet them to establish specific concerns and find out

the scope of the problem. They meet in their homes, churches and on a time

schedule that most residents can attend.

Neighborhood Traffic Teams (NTT) are established.

Traffic studies are performed to identify what the real measurable conditions

are.

Education components are implemented as agreed upon by the NTT.

The public works engineers expect that the NTT will invest time into meetings

and do communication between themselves and other residents, school officials or

businesses. Sometimes public works never gets to this phase because the

neighborhood doesn’t feel the time expenditure is worth solving the problem they

have. To date (2004) 44 Neighborhoods have requested the 3-E process and of

those

o 14 Neighborhoods are active in ongoing efforts

o 21 Requests are closed due to lack of response

o 9 have been completed with satisfaction

Examples of programs we implement if we find out there is a problem

o Friendly Streets Yard Sign

o Pace Car program

o Neighborhood traffic safety pledge

o Walking School Bus Program

3-E programs seem to concern school areas. Residents are most concerned about

speeding in school routes and near schools.

We perform after studies to determine effectiveness

After studies are performed with standard civil engineering methodology, then

the results are reported back to the residents. If there has been very little change

then the public works department reaches for…..

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The Enforcement phase

In the enforcement phase, we not only engage one or two police officers,

public works actually give residents a radar gun and instruct them how to use it.

This does two things.

o Verifies that the milder forms of speeding control measures through

community commitment and education have been effective

o Allows residents the ability to tattle on speeders by writing down their

license plates and turning their findings over to the police who can issue

letters of warnings to the offending drivers.

If none of this works the next step is….

An Engineering Solution

Some of the engineering traffic solutions for speeding are traffic circles, chicanes,

speed bumps and tables, chokers, bulbs and highlighting speed signs. For example

we can put a bright border around a speed sign to make it stand out. We can also put

speed signs in the middle of the street near pedestrian crossing facilities. The point is

engineering solutions that change the design of the road should be the last strategy to

be used to solving residential speeding.

Steve Cope said, “Why speeding exists is due to poor driving behavior. That is our

driving culture, unfortunately, and what we are up against. My future goal of all public

works should be to measure the successes and failures and then alter their own practices

as necessary.”

Residential Streets

Onstreet parking

Onstreet parking has a traffic calming effect in three ways.

1. It narrows and organizes the lanes of through travel when the road is 44 or more

feet in width.

2. It constricts travel to one lane on narrower streets so that cars cannot pass each

other and must stop to let another car through.

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3. Causes a bit of anxiety to some drivers and makes them slow down so that they do

not have an accident with a stationary vehicle.

The strengths of onstreet parking is that parked cars act like chokers and other narrowing

street devices without being a permanent fixture to that road. The weakness are that

accidents do occur from occasionally a parked driver not looking for traffic and opening

his car door into the lane of travel of a moving car. Children who tend to dart out into the

street are at increased risk from parked cars as by the time the driver sees them, they are

already in the lane of activity.

Lanes Three-lane roads Three-lane roads are marvelous engineering traffic-calmers. Built to enhance traffic

flow where left hand turns are causing congestion, they have the capacity of a four-lane

undivided road during rush hour. They are friendly to pedestrians and cyclists since there

is more room to include bike lanes aesthetically. The slower speeds are especially

beneficial to the older driver.

Three-lane road volumes should be from 10,000 to 16,000 vehicles per day. Well-

designed and appropriate application of a three-lane road can handle up to 28,000

vehicles per day. In order to work well three-lane candidates should have a fairly good

line of sight, not involve railroad tracks, not have excessive busing beyond school buses,

very few controlled intersections, and have about 50 access points per mile. Some worry

that the Two-Way Left Turn Lanes, (TWLTL), are “suicide” lanes. Improperly built,

three-lane roads can combine with impatient drivers and can lead to unsafe driving, but

that is true on any facility. It is important to have the TWLTL placed where it would be

maximized and a nontraversible median, preferably landscaped in residential or park

settings where the TWLTL is not truly needed.

Because three-lane roads are a natural traffic calmer it is vitally important that there be

no additional impedance to traffic. Right turn lanes need to be installed on high volume

corners in order to move as much traffic out of the through lane as possible at signalized

intersections with a right on red allowed. Three-lane roads in combination with

roundabouts keep a good speed of 25 to 35 mph depending on the roundabout and

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Figure 1: Bus and Bike

Lane Courtesy of UK

volume. Three lane roads should have 12-foot through-lanes and either designated and

well marked bus, bicycle lanes or both.

Three-lane roads are a safety benefit. A three-lane road has a 25% lower crash rate

than a four-lane undivided. Three-lanes tend to make accidents less severe since they

eliminate weaving and in some cases eliminates speeding. The greatest accident

reduction is in rear-end collisions. In general, rear-end crashes are reduced by about 50%

because it moves those vehicles that want to stop to make a left turn out of the thru-lane.

Designated Lanes

Designated lanes can facilitate multi-

modalism that benefits the nondriver and

community. For example, designated bus

lanes for bus rapid transit (BRT) assure

better schedule compliance and, under

some conditions, can nearly compete with

the automobile by shielding the buses

from congestion delays. A designated

lane eliminates one of the through lanes and thus increases congestion on the lanes

remaining. In terms of traffic calming, a little congestion is not a bad thing, but too much

congestion will increase the social impacts beyond the safety and/or aesthetic benefit.

Mixed designated bus and bike lanes have been used in

various cities around the country with some degree of

success. A number of communities are using shared bus

and bike lanes to give preferential treatment to both bikes

and public transport. Examples currently include Tucson,

Ariz.; Madison, Wis.; Toronto, Ontario; Vancouver, BC;

and Philadelphia, Pa. Often the lanes are also able to be

used by taxis and right-turning vehicles. Because buses and bikes will pass each other in

these lanes, lane width is an important issue. The city of Madison likes to use 16-foot

lanes to allow a clear three feet of separation between the bicyclist and a passing bus.

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But if either bus or bike traffic is light and space is limited the width of a shared lane

might be 14 feet or even less.2

Bike-lanes help to define a roadway surface by constraining the through-lane both

physically and visually. Bus and bike designated lanes actually slow traffic to a

reasonable speed without directly impeding the drivers or altering the geometric design of

the roadway in terms of new concrete poured or removed. Bike lanes can help make

riders more visible to drivers, increasing the safety for bicyclists.

Often bicyclists object to traffic calming measures fearing that it will destroy or impair

a street's rideability for cyclists. But Clarke and Dornfeld (FHWA, 1994) found from

studies in Europe and the United States that traffic calming actually encouraged bicycling

use.

David Davies, presenting at the 1999 Velo City conference in Graz, Austria, wrote

that "traffic calming should benefit bicyclists in so far as it reduces motor vehicle speeds.

Indeed, Hass Klau (1991) found that it was a more effective way of encouraging cycling

than the creation of cycle routes."

Curves

A straightaway encourages higher speeds. Gently curving a road not only slows a

vehicle because of the laws of physics, but also shortens the driver line of sight and

encourages drivers to “pay attention” to the road as it meanders. It can also be more

scenic which will slow many drivers down. People tend to linger where it is pleasant and

move hastily through unpleasant areas.

Intersection Geometrics At speeds higher than 30 miles per hour, control systems like traffic signals are often

needed. Larger intersection designs, roundabouts, medians and islands, turning bays,

staggered signals, and overpasses are particularly useful when intersections are

accommodating various and unequal modes of traffic (e.g., pedestrians, cyclists, trams,

and drivers). The downside is that enlarging an intersection requires not only additional

space but also time—a resource that is not always available or desirable. For every

second given to one direction, a corresponding second must be subtracted from another.

2 http://www.bicyclinginfo.org/de/onstreet.htm

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This decrease often translates into lost time for all users, for they must now navigate an

unusually large intersection, or stare an unusually long time at a red light Whereas at

slower speeds vehicles can move much more closely together and drivers can use eye

contact to engage and make decisions especially with pedestrians and cyclists present.

Narrowing intersections allow for quicker and more multilayered operations. For some

intersections this allows for a greater capacity across all modes.

Signals and stop signs should be the last resort for traffic calming. Studies have

shown that they increase congestion on roads and their impact on safety is mixed as

drivers tend then to trust too much in the intersection controlling devices and relinquish

part of their vigilance to other drivers and pedestrians.3

Raised Intersections

Raised intersections are flat raised areas rather like traffic

tables that cover entire intersections, with ramps on all

approaches and often with brick or other textured materials on

the flat section and ramps.4

According to the Institute of Transportation Engineers5,

these work well when combined with other traffic calming

measures, and should be applied in areas where loss of parking

would be unacceptable. Other traffic calming solutions sometimes eliminates parking by

narrowing the street as it approaches an intersection or the creating of engineering

devices can sometimes require parking space for proper implementation. Other issues to

consider are the surface condition of the street as changes in elevation are created. A

good example is the increased need for proper drainage with regards to the additional

change in runoff flow and direction that would occur with raised intersection.. Ideally,

the raised intersection should be at sidewalk pavement elevation.

The advantages of this intersection treatment are it reduces midblock speed by 10%

while having no effect on access.6

3 King, Michael, "Calming New York City Intersections", 1993,

http://gulliver.trb.org/publications/circulars/ec019/Ec019_i3.pdf 4 TE/FHWA Traffic Calming CD-ROM

5 Ibid

Courtesy ITE.org

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Pork Chops and Chanelization and diverters

Pork chops, and diverters like the star

diverter seen in the picture to the right

allow for clearer directed traffic flow.

However these types of treatments tend to

frustrate drivers and also can divert

emergency vehicles unnecessarily. Raised

pedestrian crossings, raised intersection

pavement (like a table but for the entire

intersection), roundabouts, and other non intersection control devices should be favored

before reaching for access limiting solutions such as these.

Roundabouts

Roundabouts are ideal intersection traffic

calmers on roads. .They are versatile tools. For

example, instead of a stop sign or signals at the

end of an exit ramp off of the expressway, why

not a roundabout? The Minnesota Department

of Transportation uses them for some exit ramps

off of I-35.

6 http://www.ite.org/traffic/raised.htm

Star Diverter: Picture Courtesy of Walkable Communities

Communitiey

Roundabout exit off of I-35: Courtesy MN-DOT

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Interview with James Rosenow, P.E. Minnesota DOT Geometrics and Design Engineer on the process of constructing a good roundabout. Roundabouts are unlike any other type of intersection devices in that they are tailor-

design oriented. No two roundabouts are alike and no two roundabouts have exactly the

same operating speed across all classes of vehicles even if the intersections appear very

similar. The key to Roundabouts is the horizontal curvature and lane width for its

slowing capability. There is no way to determine in advance what that will truly be.

One of the design keys is the Apron. Most medium sized emergency vehicles will be

able to negotiate MOST medium sized roundabouts without resorting to mounting the

apron. Usually, only the hook and ladder trucks, and Mayflower moving vans are the

only vehicles that must use the apron to negotiate a turn through the roundabout. Care

must be taken not to counter the traffic-calming element by making it so that large

emergency vehicles expect very little delay. Anything a large vehicle can do, a car can

do faster. In order to use a roundabout one has to accept some small delay in emergency

vehicle time.

Design Investigation

In order to have exact delay models for any roundabout, first, lay out the potential

roundabout on paper. . There is software that can also help with this, Auto Turn

Software is one, Auto CAD is another. In this software, one can pick the design paths,

horizontal turns and types of vehicles. The software will show where the tires end up at

all times throughout the turn. Then, if possible lie out a mock roundabout, and actually

run the emergency vehicle of concern through the intersection that has been

approximately “papered” for consideration.

Policy Review

Once the investigation has been concluded, it is important to do a policy review.

A policy review has two different steps.

A review of existing policies to make sure that nothing is in violation with the

proposed design

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A review of the design to make sure that all needs and purpose are met in regard

to the intersection and transportation grid.

Design and Construction

This is the final phase. Actually designing and constructing a roundabout that will do all

the things it’s supposed to do. This will be the result of the Design investigation, and the

Policy Review, and should be done with lots of public input and education.

Comparative Safety of Roundabouts Roundabouts may improve safety at an intersection by eliminating or altering

conflicts, the number of conflicts being key to intersection design safety, decreasing

speeds into and through the intersection and reducing the speed differential on the streets

as a whole. Refer to figure 5.2 and 1. Several studies in Europe, the U.S., and Australia

have found that roundabouts perform better in terms of safety than other intersection

forms. In particular, single-lane roundabouts have been found to perform better than

two-way stop-controlled intersections in the U.S. Although the frequency of reported

crashes is not always lower at roundabouts, the reduced injury rates are usually reported.

Safety is better in the small or medium capacity roundabouts. While overall crash

frequencies have been reduced, the crash reductions are most pronounced for motor

vehicles, less pronounced for pedestrians, and about the same for bicyclists, depending on

the study and bicycle design treatments7

7 FHWA, “Roundabouts: An informational Guide” chapter 5, RD-00-67, June 2000

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Figure 1Pedestrian Conflict conventional and roundabout

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Problems with roundabouts

While roundabouts are good traffic- calmers, for some pedestrian situations, they are

less than ideal8 For example, motorized volume that is too heavy at times to provide a

sufficient number of gaps acceptable for pedestrians may warrant a pedestrian signal

equipped with audible devices to assist people with visual disabilities. 9

Bicyclists on Roundabouts In low speed roundabouts, traffic and bicycles can share lanes. Bicycles merge into

traffic like a car would. This is not impossible when roundabouts are calming traffic to

15 – 25 mph, which is common for residential roundabouts. Entering motorists yield to

bicyclists just like you would any moving vehicle. Cyclists should not be “cut off” by

exiting motor vehicles.

Roundabouts also tend to have a wide sidewalk for pedestrian and cyclists to share.

However, cyclists MUST yield to pedestrians if they are sharing their space.

The rule of thumb with Roundabouts space sharing by multimodalities is the slowest

vehicle is yielded to.

Roadside Treatments Vegetation Vegetation sounds simple, but comes actually with many hidden constraints. Cost,

hardiness, maintenance, customer satisfaction, visibility and safety are all major factors to

be considered.

Trees come in a variety of species, heights, trunk

thickness, colors, shapes, and growth rates. Trees

need room for their roots to absorb water. They

need their trunks exposed to air; they need to be

able to endure road salt. They also are variable in

price.

8 Safe Pedestrians and a Walkable America: Pedestrian Forum, Federal Highway

Administration, vol 22, Fall/Winter 2002. 9 www.tfhrc.gov/safety/00-0672.pdf

Courtesy of PPS

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Traditionally, engineers do not like trees due to safety and costs issues. However,

street trees tend to slow traffic by enhancing the visual environment, seeming to narrow a

road visually, and offering shade to reduce glare. Tall trees give the perception of

making a street feel narrower, slowing people down. Closely spaced trees give the

perception of speed (they go by very quickly) slowing people down. A treeless street

enhances the perception of a street being wide and free of hazard, thereby increasing

speeds. Increased speed leads to more accidents.10

A caveat must be mentioned. Trees

can become deadly if placed to close to the curb on streets where the posted speed is

more than 30 mph. Trees can serve as a buffer between moving vehicles and pedestrians

increasing pedestrian safety. The issue of trees beside roads is a hot subject of debate.

Does the benefits of the trees outweigh the risk of a driver striking them? Some learned

professors like Kathlene Wolf, Ph.D. University of Washington believes that the benefit

of trees far outweighs the risk in a low speed environment.

Shrubs and tall grasses can also be used along

with floral selections. Shrubs can occlude

driver visibility for pedestrians and also bike

traffic if a bike path is along side the road but

grade separated. A hedge can be better as

pedestrians and cyclists usually cannot traverse

a hedge. The hedge however should end at least

150 feet before an intersection to improve the

diver’s visibility of all incoming traffic,

pedestrian, cyclists, and drivers from cross streets to the intersection.

Often, roadside vegetation landscaping efforts can irritate homeowners because native

plants are often considered to be weeds. Indeed native plants tend to “be weedy” and

insinuate themselves into lawns. Thus public involvement is necessary when choosing

landscaping. Also municipalities tend to be reluctant to increase maintenance costs by

maintaining flowerbeds instead of grass that only has to be mowed.

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http://www.coloradotrees.org/benefits.htm

Figure Courtesy Walkable Communities

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Artificial Structures Artificial structures include light

poles, flags, benches, bus stops, etc. For

traffic calming it is important for these

fixtures not to be so close as to impede

traffic significantly, be in danger of

being hit by an unusually large vehicle

such as a fire truck, or endanger people

waiting or resting along the way. However, with the proper planning, the roadside

environment can seem to be an extension of space to the roadway, which might slow

down traffic if there is a lot of street life and color.

Access

Access is one of those hot topics in regard to Traffic calming that has stirred a lot of

debate. Access means many things from pedestrian access, to adults with disability

access and vehicle access. Many organizations from many states are opposed to Traffic

Calming for reasons of accessibility issues. This report encourages maintaining access.

Finding traffic calming solutions that do not conflict with the accessibility objective is the

key.

What are the engineering and other solutions that allow for accessibility.

1. If the AADT is in the range of 6000 AADT and 15,000 AADT, with a low growth

forecast, a three-lane road may be the best lane configuration. It is not unusual

for a three-lane road to achieve LOS C to D if the traffic volume is stable at as

high as 24,000 vehicles per day. This road configuration, which encourages a full

use of the Two-Way Left-Turn Lane (TWLTL), functions best when there are 50

to 80 access points to the roadway per mile. Signals on a three-lane road should

be minimal, no more than 1 fully signalized intersection per every two miles.

This road works best in combination with roundabouts, or right turn lanes at

intersections, and vegetated medians where the TWLTL is not maximized. The

maximization of a TWLTL is when there are enough vehicles using the facility

throughout the day so that they become a visual inhibitor to other drivers, who

would otherwise be tempted to use the lane for through driving purposes.

Kungsportsavenyn Göteborg, Sweden:

Courtesy PPS

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2. Narrowing of the lanes from 13 feet to 10 to 11 foot and adding horizontal and

vertical curvature to the road. (Please note that 3 lanes do not work on “hilly”

roads as well.) Road narrowing may be considered as another supportive measure

to vertical deflections such as speed humps and raised intersections. It is not as

effective a speed-reducing device in itself, but it can act as a reminder or

encouragement to drive slowly or calmly.

3. Adding vertical visual height in the form of street trees and vegetation alongside

the road

4. Lighting that is reduced and focused

5. Adding transit on designated Transit and bike lanes and reducing the number of

through lanes.

6. On street parking

7. Speed trailers

8. Pace cars

9. Temporary devices used intermittently to discourage unnecessary cut through

traffic on good weather days.

With Emergency vehicles it is not just about whether the vehicle can get through, but

the speed. Emergency vehicle access and traffic calming often seems to be in conflict.

But it doesn’t have to be. Choosing an educational approach, choosing enforcement, and

stretching the alternatives along with using combinations of solutions can still allow

access but calmer streets! Every second counts in an emergency is an old adage. Getting

there safely however, is even more important. Emergency vehicles CAN run in Bus

lanes, they can run in Commercial Vehicle Lanes and deal with less congestion then they

currently experience. In the case of roundabouts, although there is delay, there is also

delay at intersections even signalized ones because the emergency vehicle protocol is to

SLOW at intersections in order to avoid being involved in a right-angle collision with an

unaware driver. Thus, a roundabout in reality is probably as fast if well designed and

constructed.

Below in table four are the results of studies conducted in Oregon on the effects of

different traffic calming devices on Emergency vehicle times. As you can see, there is

some delay. However, roundabouts are not significantly different in their effect than 14

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foot-bumps. The delay is consistent with various reports that traffic calming

neighborhoods typically cause only a 1 to 2 minute aggregate delay for the entire route.

Table 4 The results of a Portland Oregon study in 1995 are as follows.11

Device Delay Speed of negotiation

Access

22 foot tables (bumps

depending on curvature)

0 to 9.2 seconds Minor

Problems

14 foot bumps 1.0 to 9.4 seconds Minor

Problems

Roundabouts 1.3 to 10.7 seconds Some

Constraint

Raised Intersection N/A 15 mph Minor

Problems

Lighting

The important thing to remember about lighting at night is that the more brightly lit a

street is, the more it will resemble an airport landing strip. But if you're admiring the

spectacle, I hope you appreciate the costs involved in staging it. Leaving the lights on is

more expensive than you'd think. It not only costs a chunk of change, but it also takes a

surprising toll on the environment. The proliferation of artificial lighting threatens

wildlife, ruins habitat, fouls the air, squanders resources, and blocks our view of the

heavens. Research increasingly indicates that our bodies do better when they're kept in

the dark during sleeping hours. Exposure to light at the wrong time of day has been

linked to many maladies. Last year, for example, researchers at the University of

Pennsylvania and at the Children's Hospital of Philadelphia released a joint study that

found that children younger than 2 who slept with a night-light on were more likely to

develop nearsightedness during childhood and teenage years. "There's no doubt, light is a

powerful regulator of human physiology," says George C. Brainard, a professor of

neurology and the director of the Light Research Program at Philadelphia's Jefferson

Medical College.

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Exposure to bright light at night can disrupt the internal clocks that make our various

circadian cycles tick. Such cycles affect behavioral rhythms, daily changes in blood and

urine chemistry. In the short term, the disruption of biological rhythms can produce

grogginess, depression, and impaired thinking.12

Inappropriate lighting can undo all the work and expense of traffic calming put into a

roadway. The better one sees, the more confidence one has, and the faster one moves.

While that sounds good on paper, this high powered illumination is not as safe as it

would appear to the driver. Illumination is usually directed at the roadway, and

pedestrians and cyclists can still be obscured by the dark shadows along a route until it is

too late. High intensity lighting is no guarantee of safer driving conditions. So what

should be considered with lighting? In order of importance…

1. Does the area really need lighting?

2. Does the system provide safety and security?

3. Is the hierarchy of lighting oriented to the needs of pedestrians as well

as motorists?

4. Is the light distribution uniform and efficient?

5. During the day do the fixtures enhance or diminish the aesthetic

qualities of the roadway and the community?

6. Is the lighting intrusive to abutters?

7. Does the light quality produce unwanted glare?

8. Is the system cost-effective for the community in terms of utility costs,

construction, and maintenance?13

The important thing to remember is for residential streets, less is more.

Lamp color differences can be used to great effect in public lighting to delineate a

lighting hierarchy throughout the town. Because yellow lighting causes the landscape to

appear as shades of gray, white lighting is generally preferred where accurate color

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Bureau of Traffic Management, Portland Department of Transportation “,The Influences of Traffic

Calming Devices on Fire Vehicle Travel Times”, January 1996 12

Bower, Joe, :The Dark Side of Light" Audubon March -April 2000 13

http://www.frcog.org/ch8.PDF

23

rendering is needed to improve the perception of outdoor environments. This is especially

important at the pedestrian scale.14

Illumination lighting in traffic calming is a new field to be explored. Light levels, the

colors, and even the dispersal all have an effect on the human mind. If it didn’t,

restaurants would not waste their time paying attention to such things as lighting. Nor

would photographers. The real question is at what light levels, colors, and quality of

peripheral lighting effect impacts the speed of traffic?

Surfaces

This category of traffic-calming

devices includes signing, pavement

marking, colored and textured pavement

treatments, and rumble strips. These

devices provide visual and audible cues

14

Ibid.

Courtesy of FHWA

24

Figure 3 The City of North Vancouver

Figure 2 Courtesy of Walkable

Communities

about the traffic-calmed area. Colors and textures that contrast with those prevailing

along the roadway alert motorists to the need for alertness.

Pavement treatments can be applied to the

entire traffic-calmed area or limited to specific

street uses. The texture or color should be a

noticeable contrast to the approaching roadways if

speeds are to be reduced. Installation of

directional, warning, and informational signs and

pavement markings should conform to the Manual

on Uniform Traffic Control Devices guidelines, as

applicable.

A part of the sign/pavement marking

approach to mitigating traffic in residential

areas includes painting of stripes/lines on the

roadway and other patterns that are designed

to have a psychological impact on drivers.

Although such patterns are basically intended

to slow vehicles rather than reduce traffic,

they should make passage over residential streets less desirable than if the roadway were

untreated, in effect, encouraging the use of alternative routes.

A pattern that is successful is that of painting transverse bands. Painted lines are

applied to the road at decreasing intervals approaching an intersection or "slow-down"

point. They are intended to give the impression of increasing speed and motorists react by

slowing down. These can be used for intersections, changes in geometric curves to slow,

and other important "hot spots" where the driver's attention on the road is needed.

The use of paving materials such as brick, cobbles, concrete pavers, or other materials

that create variation in color and texture reinforces the identity of the area as a traffic-

restricted zone. These different surface treatments produce constant small changes in

vertical alignment. A noted limitation to textured pavements such as cobblestone

is that they may present difficulties for pedestrians and bicycles, particularly in wet

conditions.

25

Nontraditional approaches Second Generation Traffic Calming Excerpt from “Why Don’t we do it in the Road” by Linda Baker

In Suzhou, China, the traffic rules are simple. There are no rules. A city of 2.2 million

people, Suzhou has 500,000 cars and 900,000 bicycles, not to mention hundreds of

pedicabs, mopeds and assorted, quainter forms of transportation. Drivers of all modes pay

little attention to the few traffic signals and weave wildly from one side of the street to

another. Defying survival instincts, pedestrians have to barge between oncoming cars to

cross the roads.

The chaos associated with traffic in developing countries is becoming all the rage

among a new wave of traffic engineers in mainland Europe and, more recently, in the

United Kingdom. It's called "second generation" traffic calming, a combination of traffic

engineering and urban design that also draws heavily on the fields of behavioral

26

psychology and -- of all subjects -- evolutionary biology.15

Rejecting the idea of

separating people from vehicular traffic, Woonerf is a concept that privileges multiplicity

over homogeneity, disorder over order, and intrigue over certainty. In practice, it's about

dismantling barriers: between the road and the sidewalk, between cars, pedestrians and

cyclists and, most controversially, between moving vehicles and children at play.

The idea of the street as a flexible community space is a provocative one in the United

States, precisely because other "traditional" modes of transportation -- light rail, streetcars

and bicycles -- are making a comeback in cities across the country. The shared-street

concept is also intriguing for the way it challenges one of the fundamental tenets of

American urban planning: that to create safe communities, you have to control them.

"One of the characteristics of a shared environment is that it appears chaotic, it appears

very complex, and it demands a strong level of having your wits about you," says U.K.

traffic and urban design consultant Ben Hamilton-Baillie, speaking from his home in

Bristol. "The history of traffic engineering is the effort to rationalize what appeared to be

chaos," he says. "Today, we have a better understanding that chaos can be productive."

But the implications, especially in the United States, are nothing less than radical.

Reversing decades of conventional wisdom on traffic engineering, Hamilton-Baillie

argues that the key to improving both safety and vehicular capacity is to remove traffic

lights and other controls, such as stop signs and the white and yellow lines dividing

streets into lanes. Without any clear right-of-way, he says, motorists are forced to slow

down to safer speeds, make eye contact

with pedestrians, cyclists and other

drivers, and decide among themselves

when it is safe to proceed. "The more

you post the evidence of legislative

control, such as traffic signs, the less the

driver is trying to use his or her own

senses," says Hamilton-Baillie, noting he

has a habit of walking randomly across

15

Baker, Linda, " Why don't we do it in the road?" May 20, 2004, www.salon.com

European Woonerf: Courtesy of PPS.org

27

roads -- much to his wife's consternation.

Though most engineers bulk at this due to possible litigation or traditional codes, there

is precedence on residential streets where there are no clear markings for parking, biking,

or even through lanes.

The "self-reading street" has its roots in the Dutch "woonerf" design principles that

emerged in the 1970s. Blurring the boundary between street and sidewalk, woonerfs

combine innovative paving, landscaping and other urban designs to allow for the

integration of multiple functions in a single street, so that pedestrians, cyclists and

children playing share the road with slow-moving cars. The pilot projects were so

successful in fostering better urban environments that the ideas spread rapidly to

Belgium, France, Denmark and Germany. In 1998, the British government adopted a

"Home Zones" initiative -- the woonerf equivalent -- as part of its national transportation

policy.

"What the early woonerf principles realized," says Hamilton-Baillie, "was that there was

a two-way interaction between people and traffic. It was a vicious or, rather, a virtuous

circle: The busier the streets are, the safer they become. So once you drive people off the

street, they become less safe."

Contrast this approach with that of the United Kingdom and the United States, where

education campaigns from the 1960s onward were based on maintaining a clear

separation between the highway and the rest of the public realm. Children were trained to

modify their behavior and, under pain of death, to stay out of the street. "But as soon as

you emphasize separation of functions, you have a more dangerous environment," says

Hamilton-Baillie. "Because then the driver sees that he or she has priority. And the child

who forgets for a moment and chases a ball across the street is a child in the wrong

place."

Research has shown that fatality rates at busy intersections, where two or three people

were being killed every year, dropped to zero when controls and boundaries were taken

away. [Reference]

28

There's another step in the second-generation logic process. Safety analysts have known

for several decades that the maximum vehicle speed at which pedestrians can escape

severe injury upon impact is just less than 20 miles per hour.16

Research also suggests that an individual's ability to interact and retain eye contact with

other human beings diminishes rapidly at speeds greater than 20 miles per hour. Higher

vehicle speeds limits a driver’s peripheral vision. At 15 miles per hour (mph), the

driver can comfortably see and notice pedestrians along the sidewalks, close to the

vehicle. At 25 mph, nearby pedestrians, including children that may be playing, are no

longer in the field of vision. At 30 mph and above, the field of vision is focused almost

exclusively on the far distances. 17

One theory behind this magic bullet, says Hamilton-Baillie, is that 20 mph is the

"maximum theoretical running speed" for human beings. (Evolutionary biologist E.O.

Wilson has drawn similar conclusions.) "This is of interest," he says, "because it suggests

that our physiology and psychology has evolved based around the potential maximum

impact on the speed of human beings."

The ramifications go beyond safety, says Hamilton-Baillie, to bear directly on the

interplay between speed, traffic controls and vehicle capacity. Evidence from countries

and cities that have introduced a design speed of 30 kilometers per hour (about 18.5 mph)

-- as many of the European Union nations are doing -- shows that slower speeds improve

traffic flow and reduce congestion. 18

"This surprises many people, although mathematically it's not surprising," Hamilton-

Baillie says. "The reason for this is that your speed of journey, the ability of traffic to

move smoothly through the built environment, depends on performance of your

intersections, not on your speed of flow between intersections."

Combining slower speeds with a reduction in traffic controls, in other words, may have

more than public safety and shared-space benefits. It also appears to profit the driver.

(This is the logic behind the modern roundabout, a redesigned version of the classic

16

U.K. Department of Transportation, Killing Speed and Saving Lives, London, 1987. 17

Dane County Model TND Ordinance: Appendix B: Design for Safe Streets, Febuary 2004 18

Beaty, William, " TRAFFIC EXPERIMENTS" AND A CURE FOR WAVES & JAMS, 1998

29

traffic circle that is replacing signalized intersections in the United Kingdom and is

gaining acceptance among transportation officials in the United States).

"You can see this is the way to break out of the pro-car, anti-car debate," Hamilton-

Baillie says. "Because the shared approach very much accepts the car as a vital useful

component in cities that will remain with us for some generations to come."

In the United States, as one might expect, policymakers haven't exactly embraced the

virtues of ambiguity and uncertainty embodied in second-generation principles.

"Woonerfs are certainly being planned on private property," says James Daisa, a project

manager at Kimley-Horn Associates and a national expert on pedestrian-friendly

development. "But the concept has yet to come to bear on public streets." City codes are

part of the problem, he says. The reluctance of traffic engineers is another."

"It's clear that advocates and private developers aren't sufficient to bring about a true

woonerf," wrote Flint. "The traffic engineers need to be in the room, and they need to

understand the concept. A fact-finding trip to the Netherlands may be in order."

Redesign the street environment as an active community space, and you equalize the

power relationship between cars and human beings "The real gain in urban quality does

not come from clawing back areas of the city from cars, as important as that is," said

Hamilton-Baillie, who gave a talk at the Portland Department of Transportation last fall.

"But the next step is how you apply a broader approach to those areas where you need

cars and trucks, bicycles and shops, and pedestrians and children's play, all those

different functions to take place in precious urban space."

The absence of traffic controls means that people are out for themselves; the trick is,

they have to look out for everyone else as well. Second-generation traffic design is a

curious mix of selfishness and altruism, of order amid chaos. And, after a fashion, it just

might work.

30

31

These tables are wonderful. But, there is no explanation given. In the final version, they

have to be connected to the corresponding sections.

Table 2 Speed Impacts of Traffic Calming Measures (Ewing, 1999)

Sample Size Avg. Speed

Afterward (mph) Avg. Speed

Change Avg. %

Change

12' Humps 179 27.4 -7.6 -22

14' Humps 15 25.6 -7.7 -23

22' Tables 58 30.1 -6.6 -18

Longer Tables 10 31.6 -3.2 -9

Raised Intersections 3 34.3 -0.3 -1

Circles 45 30.2 -3.9 -11

Narrowings 7 32.3 -2.6 -4

One-Lane Slow Points 5 28.6 -4.8 -14

Half Closures 16 26.3 -6.0 -19

Diagonal Diverters 7 27.9 -1.4 -0.5

From www.trafficcalming.org.

Effectiveness of the Various Treatments (Arizona)

Management Device

Speed Reduction

Safety Access Restriction

Maintenance Problems

Level of Violation

Cost

Speed Humps Limited No

Documented

Problems

None None N/A Low

Chokers Minor Improved

for

Pedestrians

None Truck Hit

Curbs

N/A Moderate

Roundabouts Likely Unclear None Vandalism Low Moderate

Channelization Possible Improved Some Vandalism Potentially

High

Moderate

Semi-diverter Likely Improved One

Direction

Vandalism Potentially

High

Moderate

Diagonal Likely Improved Thru Traffic Vandalism Low Moderate

32

Diverter

Impact on Emergency Vehicles

Table 5 Safety Impacts of Traffic Calming Measures, U.S. Experience

Number of

Observations Average Number of

Collisions % Change in

Collisions

Before After

12' Humps 49 2.7 2.4 -11%

14' Humps 5 4.4 2.6 -41%

22' Tables 8 6.7 3.7 -45%

Circles 130 2.2 0.6 -73%

All Measures – 192 2.6 1.3 -50%

(Ewing, 1999; www.trafficcalming.org)

Expected speed reduction effect of various traffic calming measures19

Different Treatments Upper limit of 85th percentile

speed (mph)

Range of Speed (mph)

Before After Before After

Verticle curves 46.6 18.6 28 - 40.4 11.2 – 15.5

Horizontal Curves 46.6 28 28 - 40.4 13.7- 21.8

Narrow road to single lane 46.6 28 28 - 40.4 13.7- 21.8

Roundabout 46.6 28 28 - 40.4 13.7- 21.8

Road narrowing to reduce width 46.6 43.5 28 - 40.4 25 - 34.2

Central islands 46.6 43.5 28 - 40.4 25 - 34.2

Table 6 Typical Costs of Traffic Calming Measures (Seattle Engineering Dept., 1996;

Zegeer, et al 2002; U.S. dollars)

19

http://www.its.leeds.ac.uk/projects/primavera/p_calming.html

33

Measure Typical Costs

Asphalt walkway $30-40 per linear foot for 5-foot wide walkway.

Curb ramps $1,500 per ramp.

Bike lanes $10,000-50,000 per mile to modify existing roadway (no new construction).

Chokers $7,000 for landscaped choker on asphalt street, $13,000 on concrete street.

Curb bulbs $10,000-20,000 per bulb.

Traffic circles $4,000 for landscaped circle on asphalt street, $6,000 on concrete street.

Chicanes $8,000 for landscaped chicanes on asphalt streets, $14,000 on concrete streets.

Street closures $6,500 for landscaped partial closure, $30,000-100,000 for full closure.

Marked crosswalk $100-300 for painted crosswalks, $3,000 for patterned concrete.

Pedestrian refuge island $6,000-9,000, depending on materials and conditions.

Center medians $15,000-20,000 per 100 feet.

Traffic signals $15,000-60,000 for a new signal.

Raised intersection $70,000+ per intersection

Traffic signs $75-100 per sign.

Speed humps $2,000 per hump

Traffic Calming and Transit

.

Traffic calming measures can make the trip to the transit station more walkable and

convenient, while providing space for amenities to make the trip more pleasant. Although

traffic calming and transit seem to be natural partners, sometimes their goals can conflict.

When a traffic-calming strategy performs its job well, it may interfere with the efficient

movement of a transit vehicle, or even its comfort, as when speed humps create a bumpy

ride on buses. Certain strategies can maintain the benefits of traffic calming while

allowing transit to function effectively:

Cushions enable buses to pass smoothly over an area, yet still slow smaller vehicles. Bus

"bumpouts" or "nubs" allow buses to pick up passengers without having to move out of

the traffic lane. They extend across a parking lane to meet the traffic lane (and the bus

that is in it), giving passengers a safe and accessible approach, while also saving travel

time. Nubs can be built to line up with both the front and rear doors of a standard bus,

and can accommodate amenities like bus shelters, benches, telephones and waste

receptacles. [Are there any graphics available to explain these?]

34

By and large though, as long as they are coordinated to meet the needs of a specific street

environment and its surrounding community, traffic calming and transit can work

together to provide the comfortable, convenient and safe connections that enhance a place

and promote a positive experience there. Two considerations to make are: How does

transit relate to sites where where traffic-calming improvements are needed? How can

transit and traffic calming reinforce one another in order to help people get from place to

place without driving?20

Conclusion The impacts of traffic calming devices need to be balanced against the benefits of the

traffic calming devices. Changing the geometrics of roads should be the last resort since

it is the most expensive and permanent solution. Traffic calming is most effective when

the tools are used in combinations. No one device or process will completely eliminate

speeding.

Education is the best and least expensive approach when used when there is a

complaint. Neighborhood participation and commitment is imperative when utilizing the

three E program which puts education first.

If education or compliance fails, stronger enforcement may be necessary. This can

come in the form of raising the price of a ticket to violators. For example, currently in

2005 it costs $75 dollars for a speeding ticket for an infraction within 15 miles per hour

of the limit. But what if we raised that in certain neighborhoods or municipalities where

it is a problem 3 times and enforced it?

If enforcement does not work well, then an engineering solution is needed. However,

once again it is not as simple as “one device” fits all problems. Engineering is best

when access is not limited, when the cost is as low as possible for the effectiveness, and

when cyclists, transit, and emergency vehicles are also taken into account. Much can be

done to support all these efforts and still calm traffic.

For example, roundabouts and three-lane roads not only calm traffic, but help with access

and flow. The combination, if well engineered, is a thing of transportation elegance and

beauty that will last a community for years in mature neighborhoods.

Traffic-calming tools outlined above can be effective in a variety of ways. The right

use hinges on existing conditions along a street and the desired outcomes. However, a

cautionary note about mass transit. Mass transit only works well if there is a high enough

density in population to support it. The density of an area must exceed 2000 people per

square mile. [Is this from Pushkarev and Zupan? Their study, though thorough, is quite

old and limited.] Otherwise, it has been discovered that buses, mostly empty, only add to

the congestion and not a part of the solution. [reference.]

20

Project for Public Spaces, www.pps.org

35

Apendix I Successful Programs in Others States

Provided below are the the names of Cities about the same population as Honolulu

(1,000,000) that have successful traffic calming programs. A description of what their

programs have accomplished and when their programs started.

1. Portland, Oregon .... Perhaps 100 or more treatments on the ground, with many new

streets being designed well, many pedestrian crossings, many bike lanes, many road diets

and lots of great new streets and street standards. Major efforts have been underway for

as many as 20 years.

2. Seattle, Washington .... now up to 800 or so mini-circles, their 17th road diet went into

place this summer and about 3 more scheduled, a number of radical new neighborhood

streets that are almost like woonerfs, lots of midblock crossings with refuge islands. I am

told that the city launches an average of one new pedestrian project each day. Major

efforts have been underway for about 30 years.

3. Sacramento .... we are into the fourth or fifth roundabout. They did a significant

midtown traffic calming program that has worked quite well, though still a bit

controversial .... and perhaps 20-30 project sunderway around the city. the midtown

project was most likely launched about 12-15 years ago.

4. Hartford and the greater area .... a little light on the population side, but we did a

master plan for all 14 neighborhoods, and at least six roads diets are already in place and

a lively schedule of other projects coming on line, despite this city being the poorest of

size in the nation. We just finished the planning two years ago.

5. Stamford is much larger than Hartford. We have a contract to do a traffic calming

master plan in every neighborhood. The complete planning phase of this project is

anticipated to be in the $500-1,000,000 range, which are now getting under contract.

Some sporadic things have been done in the past ... no concerted effort.

36

6. Ft Lauderdale is well into a traffic calming program, with many treatments on the

ground ... and in the region, to the north, West Palm Beach has so many treatments it is

hard to know where to point the camera.... and many are designed and executed quite

well. Much of this work was achieved over the past 7-9 years.

7.St Petersburg is a city with a road networked planned and built for a city three times

its size (sprawl sent people outward). Today the city is healing fast, and traffic calming is

a big part of the recovery of the central city. Life is flowing back toward the center at an

amazing rate. Most project are new

8. Toronto started their program about 12-15 years ago, and has expanded at a regular

basis. Although not as aggressive as the Honolulu program, there are many, varied and

workable plans and projects in place in specific neighborhoods and requests for many

more.

9. Vancouver, British Columbia. Serious efforts began about 15-20 years ago. Today

there are perhaps 100-300 mini-circles, many pedestrian crossings, many road diets

(perhaps 15 or more), vast numbers of curb extensions, and model projects in virtually all

neighborhoods. I would rate their program as the most comprehensive in Canada ... at

least on par with Seattle. Many of the outlying communities now have taken the torch....

and a number of small new villages re popping up with well designed streets.

10. Denver is complex and diverse, and their foray into traffic calming is still mixed and

unrated. Yet some of the area towns are chock full of the best achievements.... and

Denver has some noteworthy pedestrian features, medians, a few road diets and other,

transit-ways and other accomplishments.

11. Charlotte, North Carolina is a major player with a great diversity of quality streets

that are designed for low speeds, many road diets planned and on the ground, a major

new effort in the downtown, and so, so many new villages in the planning and early

development stages. The about to be built projects greatly over shadow most cities of

size. 12. Columbus, Ohio, my birth town, is in it beginning years ... with a few recent

accomplishments in planning and a few projects on the ground. in quite a diversity of

neighborhoods. I just finished a study of one neighborhood there, and two others were

completed earlier. Some older neighborhoods are being brought back to life, and traffic

calming features are key to each of these. The potential is here with a new funding

package and some steady progress with staff and elected leaders that know that they have

got to save the central city.

I believe Belleview, WA has a comprehensive planning process for traffic calming

projects. It may be worthwhile to check into it.

37

38

39

Contact Information

Friendly Streets: Naperville’s Traffic Calming Program http://www.naperville.il.us/dynamic_template.cfm?doc_id=297

Brent A. Coulter, P.E. P.T.O.E.

Senior Project Manager

E-mail: [email protected]

Steve Cope

Transportation & Traffic Operations Manager

E-mail: [email protected]

630-420-6066