RESPONDING TO CITIZEN CONCERNS
AROUT RESIDENTIAL SPEEDING

By LYNN MONTEL, Executive Director, DuPage Mayors and Managers Conference

Many communities are faced with ever-mounting citizen complaints regarding the perception of excessive speeding on local streets. Too often, however, the municipal response is to artificially lower speed limits or install unwarranted stop signs in the mistaken belief that this will solve the problem. In fact, such "solutions" actually encourage a general disrespect for traffic regulations leading to non-compliance and reduced safety.

As a means to dispel some of the myths and misconceptions that surround the speeding issue, the DuPage Mayors and Managers Conference prepared a full-color public information brochure titled the "Truth About Speeding in Residential Areas" and a companion report on the Management of Vehicle Speeds on Residential Streets.

How are speed limits determined?

Accepted engineering practice in the United States uses the concept of "prevailing speed" as the basis for posting speed limits. This is the speed that most drivers (typically 85%) find safe and reasonable for given roadway conditions. While at first glance this may seem like allowing the "wolf to guard the chicken coop", studies have shown that setting speed limits based on prevailing speed minimizes accidents and keeps violation rates at levels that can reasonably be enforced.

In Illinois, municipalities must comply with State Statutes on the establishment of speed limits. The State regulations, however, allow for prevailing speed to be adjusted downward to reflect frequent driveway access, high pedestrian volumes and high accident experience. The State of Illinois also permits 20 mph speed zones to be posted and enforced where school children are present.

What is a safe speed limit on residential streets?

Follow-up studies of pedestrian/vehicle accidents have shown that the risk of pedestrian fatality or severe spinal injury in the event of a collision with a motor vehicle increases dramatically when vehicle speeds exceed the 25-30 mph range.

In addition, the geometrical layout (curvature and width) of subdivision streets recommended by the Institute of Transportation Engineers is designed for safe operating speeds of 25 mph to 30 mph. Most local streets are designed for speeds in this range.

If we lower speed limits won't drivers drive slower?

A common misconception is that if speed limits are set well below the normal range, then vehicle speeds will drop accordingly. Before-and-after studies from Illinois and across the country, however, have concluded that artificially lowering speed limits has generally no effect on the speed at which motorists choose to drive. In many cases speeds actually increased, making traffic law violators out of even the most safe and careful drivers.

Why not install stop signs to slow traffic?

Multiway stops are intended to be used when the volume of vehicles and pedestrians is so high on intersecting streets (approximately 2,000 to 4,500 movements per day) that there is not a sufficient number of gaps between vehicles to safely enter the intersection. Stop signs are not intended for, and are not effective in, the control of speeds on residential streets.

Again, data from Illinois and other states shows that the effect of a stop sign on reducing speed is limited to a short distance around the sign itself (150 to 200 feet). Speeds often increase beyond this point as motorists "make up for lost time." Where stop signs have been incorrectly installed as speed control measures, studies have documented much greater rates of abuse of the stop control where cars do not stop or make a roll stop. No parent wants his or her children relying on an unwarranted stop sign that motorists consistently disobey.

Many communities have removed unwarranted stop signs because of these safety problems in addition to the increased noise, air pollution, and fuel consumption, that is generated.

Why not enforce the speed limits we already have?

One of the most effective methods for reducing

August 1992 / Illinois Municipal Review / Page 15

speeds is through selective enforcement of speed limits on consecutive days. Unfortunately the traditional police/radar gun approach is manpower intensive and costly. A community's budget limits the number of streets that can be routinely and effectively covered by the police department. New technology such as photographic radar may one day assist municipal governments in making speed enforcement less costly.

Are there other options?

In many cases the problem of speeding is really a concern with too much traffic on the local street. This problem becomes more pronounced when through traffic spills over onto local streets to avoid arterial traffic congestion. Continued efforts of government agencies at all levels is needed to keep our major transportation system capacity in balance with the traffic demand generated from land development.

In addition, experience seems to indicate that narrowing the roadway through reductions in building setback from the street, right-of-way, pavement width, and landscaping helps create a "tunnel" effect which gives drivers the sensation of going faster then they really are, thereby keeping speeds down. In general, municipalities may discourage excessive speeds in new subdivisions by avoiding the overdesign of streets and eliminating "cut-through" opportunities in street layout. As older, existing streets are rehabilitated it may be possible to incorporate similar speed reduction concepts.

Conclusion

There is no single magic solution to solving the problems of excessive speeds on local streets. In fact, various long-term studies have shown that residents will never be fully satisfied with either the volume or the speed of traffic in their neighborhoods.

The installation of unwarranted stop signs and artificially low speed limits will not reduce excessive speeding but will increase accident potential for both motorists and pedestrians, while giving concerned residents a false sense of security for their neighborhood traffic safety.

Police enforcement, especially with state-of-the-art equipment and the assistance of resident involvement can be effective in enforcing better speed limit compliance on streets with chronic speeding problems.

For a sample copy of the DuPage Mayors and Managers Conference's brochure and order form contact the Conference at: 1220 Oak Brook Road, Oak Brook, IL 60521. The Conference is a council of 33 municipal governments in DuPage County, Illinois. •

Page 16 / Illinois Municipal Review / August 1992