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Back to Intersection Safety Strategies Brochure
NCHRP Report 500 / Volume 5: A Guide for Addressing Unsignalized Intersection Collisions
Unsignalized intersections where speed violations and patterns of crashes related to speed violations are observed. Crash types potentially related to speed violations include right-angle, rear-end, and turning crashes.
Photo by: Texas Transportation Institute
Law enforcement is considered an important contributor for maintaining traffic safety. However, limited resources, such as staff and funds, constrain the efforts of police in providing targeted speed enforcement. Studies have shown that speed enforcement helps reduce the mean speed and, consequently, the number of injury, fatal, and property-damage-only crashes in which unsafe speed is the primary collision factor. Traffic law enforcement agencies will often select locations for targeted enforcement when crash, citation, or other sources of information suggest that the site is unusually hazardous due to illegal driving practices. Traffic law enforcement methods vary depending upon the type of program being implemented.
Plan the enforcement and prioritize the intersections that need it (see TRB Special Report 254). Such intersections should have a combination of high speed-violation rates and related crash patterns. In some cases, public input or observations by law enforcement personnel may suggest that a location should be targeted with enforcement. It is important that both the highway agency and the law enforcement agency(ies) in the jurisdiction be involved jointly in planning and operating the program.
The success of any enforcement program depends substantially on the performance of the officer in the field. It is important that all officers involved be told of the objectives and expected benefits of the program and that they be given regular feedback on their effectiveness.
It is also important to interact with the court systems operating in the jurisdiction so that the judiciary understands the objectives. It may also be possible in some cases to involve the judiciary in planning and implementing the program.
The major potential difficulty with a program of targeted speed enforcement is the potential for diverting police officers from more productive work if the locations for speed enforcement are not selected carefully. In addition, care must be taken to identify appropriate and safe locations to stop violators and issue citations.
Finally, if the court system does not adequately convict and apply sufficiently strong sanctions to the cited offenders, the program will lose its effectiveness.
Targeted speed enforcement can be implemented in a short period of time. Identified problems can be addressed almost immediately if enforcement manpower is available.
There are almost no capital costs involved in speed enforcement, but staff hours and vehicle operating costs may be substantial.
PROVEN: The effectiveness of this strategy has been established by numerous studies. The most effective enforcement is the stopping and ticketing of offenders, as opposed to automated enforcement where fines are mailed on the basis of the vehicle's license plate number. Enforcement agencies have generally found that the effectiveness of increased enforcement at specific locations has a relatively short duration of effectiveness—measured in days or weeks, rather than months or years. One study concluded that pedestrian crashes may be significantly reduced when speed enforcement is increased.
This strategy can be used in conjunction with most other strategies for improving safety at intersections.
There is a potential need for public information and education on the reasons for the targeted enforcement, particularly when targeted enforcement techniques are used in an area for the first time. A special informational campaign may be needed for the court system.
For more details on this and other countermeasures: http://safety.transportation.org
For more information contact:
FHWA Office of Safety Design
E71, 1200 New Jersey Avenue SE
Washington, D.C. 20590
(202) 366-9064
http://safety.fhwa.dot.gov
FHWA Resource Center – Safety and Design Team
19900 Governor's Drive, Suite 301
Olympia Fields, IL 60461
(708) 283-3545
http://www.fhwa.dot.gov/resourcecenter
