U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
NCHRP Report 500 / Volume 5: A Guide for Addressing Unsignalized Intersection Collisions
Unsignalized intersections where stop sign violations and patterns of crashes related to stop sign violations have been observed. Crash types potentially related to stop sign violations include right-angle and turning collisions.
Photo by: Texas Transportation Institute
Enforcement options are a potential countermeasure to unsafe and illegal motorist behavior at intersections. Studies report the reduction of traffic law violations when enforcement is used. 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.
Identify the intersections that can potentially benefit from increased enforcement. Such intersections should have a combination of high stop sign 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 have interaction 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 increased enforcement is the potential for diverting police officers from more productive work if the locations for stop sign 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 enforcement can be implemented in a short period of time. Identified problems can be addressed almost immediately if enforcement manpower is available.
There is almost no capital cost involved in increased enforcement, but staff hours and vehicle operating costs may be substantial.
TRIED: This strategy is known to be effective in reducing traffic law violations. Programs within the United States have been found to result in decreases in violations of between 23 and 83%. However, the safety effectiveness of such decreases in violation rates has not been quantified. 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.
This strategy can be used in conjunction with most other strategies to improve safety at unsignalized intersections.
There is a potential need for public information and education on the reasons for the strategies selected, 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. Also refer to Countermeasures That Work from the National Highway Traffic Safety Administration.
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
FHWA Resource Center – Safety and Design Team
19900 Governor's Drive, Suite 301
Olympia Fields, IL 60461