Problems Associated With Traffic Calming Devices

Traffic Calming

By Kathleen Calongne
Boulder, CO
January, 2003

Traffic calming devices, such as speed humps and traffic circles are spreading to communities across the United States, without regard to their risks. The U.S. Department of Transportation (USDOT) has avoided the examination of the problems associated with intentionally imposing vertical and horizontal deflection on vehicles and vehicle passengers, in order to encourage the proliferation of devices on city streets.

Deflection devices built to slow passenger vehicles, create even greater delays to emergency response vehicles. The longer wheel-base, stiff suspension, high vehicle weight, as well as the sensitive equipment and injured victims transported by these vehicles, requires drivers to slow almost to a stop to negotiate the devices safely.

An unethical attempt has been made to silence the objections of rescue personnel to delays to emergency response by deflection devices. Fire chiefs, as city appointees, fear professional retribution and often will not voice concern until the level of risk becomes intolerable. Emergency calls are not the rare events some members of transportation and city staff would like to believe. The City of Houston, Texas for example, responds to an average of 150,000 emergency medical calls and 100,000 fire calls per year. There is an average of 250,000 deaths from sudden cardiac arrest (SCA) alone each year in the United States. American Heart Association (AHA) statistics indicate that 90% of these incidents occur outside of the hospital environment. By comparison, there are approximately 5,000 pedestrian deaths per year in the United States. Few of these occur on local neighborhood streets. A ten-year study of pedestrian deaths by the U.S. Department of Health and Human Services, 1982 - 1992 found 35% of pedestrian victims were intoxicated. National Highway Traffic Safety Administration (NHTSA) statistics, Safety Facts 2000, found similar results with intoxication on the part of 31% of pedestrian victims. AHA statistics for SCA, show survivability is directly related to the response times of cities. For example, an AHA study in 1996 showed that Seattle with a response time of less than 7 minutes saved 30% of its SCA victims. New York, with an average response time of 12 minutes saved only 2%.

While delay from individual devices is sometimes measured, the cumulative effect of series of devices is often ignored. Series of devices turn seconds of delay into minutes, as vehicles fail to regain cruising speed between the devices. Calming devices impose permanent, 24-hour delays to emergency response, unlike traffic congestion which occurs periodically. A study conducted by the fire department of Austin, Texas, 1997, showed an increase in the travel time of ambulances of up to 100% transporting victims.

Members of city councils and transportation divisions often portray delay to emergency response by calming devices as simply a tradeoff for increased safety from speeding cars. They avoid making the analysis which shows which risk is greater. Ronald Bowman, a scientist in Boulder, Colorado developed an analysis to compare these risks. The results show that even minor delay to emergency response by calming devices imposes far greater risk on the community than vehicles, speeding or not. The result of Bowman's analysis, showed a risk factor of 85 - 1 from an additional one minute of delay (predicted to result from the installation of all the devices proposed for the City of Boulder at the time) before one life might be saved by the devices -- if it can be shown that the devices do save lives. Bowman's analysis, based on the curve of survivability for victims of cardiac arrest and severe trauma (AHA) has been verified by a professional mathematician and can be viewed online at: http://members.aol.com/raybowman/risk97/eval1.html.

The Bowman analysis was applied to the City of Austin, Texas by Assistant Fire Chief, Les Bunte, with similar results. The report can be viewed online at: http://home.cfl.rr.com/gidusko/texts/tfc_calm.pdf.

The results of these analyses show that deflection devices are a tradeoff of the perception of increased safety from speeding vehicles for the real risk to citizen survivability from delay to emergency response. While the Institute of Transportation Engineers' (ITE) Guidelines for the Design and Application of Speed Humps, 1997, states humps should never be placed on emergency response routes, humps and physical devices of all kinds have been installed on critical emergency response routes in cities where these projects exist. The proliferation of devices has resulted in temporary or permanent moratoriums on devices in cities such as Berkeley California, Boulder Colorado, Portland Maine and Portland Oregon.

People with disabilities complain of lasting pain and injury caused by traveling over deflection devices in vehicles. Significant testimony about the physical and psychological barrier deflection devices make to access to public rights-of-way has been given to the U.S. Access Board in Washington D.C. A web site addressing the problems of the disabled with deflection devices such as speed humps, speed tables and raised crosswalks can be found at: http:www.digitalthreads.com/rada.

Calming devices have been installed on streets to divide communities along racial and socioeconomic lines. The U.S. Department of Housing and Development (HUD) identified gates installed as part of a traffic calming project in Houston, Texas as discriminatory, ordering them removed. Gates were replaced with speed humps to create a similar, though less obvious, barrier between neighborhoods.

While calming devices are built on the premise they will reduce accidents, a comprehensive study commissioned by the ITE and the Federal Highway Administration (FHWA) on traffic calming projects in the United States concludes:

"Traffic calming in the U.S. is largely restricted to low volume residential streets. Collisions occur infrequently on such streets to begin with, and any systematic change in collision rates tends to get lost in the random variation from year to year. This limits our confidence in drawing inferences about safety impacts of traffic calming."

(Traffic Calming: State of the Practice, Reid Ewing, 1999, P. 123)

The USDOT defines traffic calming devices as geometric design features of the roadway, rather than traffic control devices. The USDOT recommends standards for the design and warrants for the use of devices that are approved traffic control devices in the Manual on Uniform Traffic Control Devices (MUTCD). The definition of traffic calming devices as geometric design features of the road has allowed devices to proliferate on city streets as a decision of local governments.

An increase in accidents has occurred after some installations. Experimental speed humps placed on a street at a school in Portland, Maine registered an increase in accidents of 35%. Accidents increased 100% after the installation of an experimental traffic circle in Boulder, Colorado. However, the circle in Boulder and the humps in Portland remain on the street today.

People across the United States are opposing the installation of deflection devices on city streets that damage vehicles, injure vehicle passengers, increase pollution and gas consumption and delay emergency response. I have researched traffic calming projects since 1996, and have compiled my research into a 400-page report on the "Problems Associated with Traffic Calming Devices." I offer the report to all interested individuals at my cost. The following is a summary of some of the issues addressed in my report.

Kathleen Calongne
CalongneK@aol.com

Resources Used For This Report

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The NMA's Position

Traffic "calming" is an euphemism for traffic obstruction and diversion. The NMA opposes any measure or regulation that is deliberately designed to inconvenience and hinder the legitimate travel of responsible motorists.