U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
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In 2000, the Federal Highway Administration (FHWA) and the Institute of Transportation Engineers (ITE) initiated preparation of an Informational Report entitled, Engineering Intersections to Reduce Red-Light Running. The principal focus of the effort was to examine the engineering features of an intersection that could reduce red-light running. The intended purpose of the report was to provide information that could be used to proactively ensure that intersections were engineered to discourage red-light running. The report was to serve as an educational tool for law enforcement agencies and others who may design red-light camera systems.
In order to develop the toolbox, ITE formed a panel of experts from federal, state and local governments, as well as academia and the private sector, to share knowledge and experiences in addressing red-light running using engineering countermeasures. In addition, a process was established to collect information and survey practicing engineers to collect the broadest information possible on the topic. The end result was a toolbox that identifies engineering features at an intersection that should be considered to discourage red-light running. Making Intersections Safer: A Toolbox of Engineering Countermeasures to Reduce Red-Light Running addresses design and operational features that may need to be upgraded as necessary. It provides a background of the characteristics of the red-light running problem; identifies how various engineering measures can be implemented to address this problem; suggests a procedure for selecting the appropriate engineering measures and provides guidance on when enforcement, including red-light cameras, may be appropriate.
Research cited in the report suggests that "intentional" red-light runners are most affected by enforcement countermeasures while "unintentional" red-light runners are most affected by engineering countermeasures. The report also establishes the essential need for sound engineering at an intersection for the successful implementation of long-term and effective enforcement activities, particularly automated enforcement. The report further concludes that education initiatives can be an effective complement for any approach or as a stand alone program in its own right. Overall, red-light running is recognized as a complex problem requiring a reasoned and balanced application of the three "E"s.
The engineering features presented in the report are categorized according to the type of problem they address. The expected benefits of various countermeasures in terms of reduced red-light running violations or crashes are presented where data are available. Other countermeasures are presented when there is substantial confidence in their effects based on the field experience of practicing engineers.
The problems contributing to red-light running that can be addressed with engineering countermeasures include signal visibility, the likelihood of stopping, eliminating the need to stop and signal conspicuity.
One recent survey shows that motorists who violate the red traffic signal frequently claim, "I didn't see the signal." In fact, 40 percent of red-light runners claim they did not see the signal and another 12 percent apparently mistook the signal indication and claimed they had a green-signal indication. For whatever reason-motorist inattention, poor vision, poor signal visibility-the motorist did not see the signal, and specifically, the red signal in time to come to a stop safely. Signal heads placed in accordance with the MUTCD should ensure their visibility for all motorists. Yet, there are locations that are still not in compliance with the MUTCD. At a minimum, stricter adherence to the guidelines and standards presented in the MUTCD are needed to improve signal visibility. The countermeasures described in the report include the placement and number of signal heads, the size of the signal display and line of sight.
In addition to improving the visibility of a traffic signal, various countermeasures can be applied to capture the motorist's attention, i.e. making the signal more conspicuous. Redundancy by providing two red-signal displays within each signal head can be effective in increasing conspicuity. LED signal lenses are beneficial in that they are brighter, which is especially helpful during poor weather or bright sunlight. Backplates improve signal visibility by providing a black background around the signals, thereby enhancing the contrast. They are particularly useful for signals oriented in an east-west direction. Finally, strobe lights are considered because they attract the attention of the motorist and provide emphasis on the signal.
Intersections and intersection devices should be carefully engineered so that the motorist is not enticed to intentionally enter the intersection on red. This may include providing additional information to the motorist regarding the traffic signal. With the additional information, the probability that a driver will stop for a red signal may increase. Additionally, the intersections must be designed so that a driver who tries to stop his/her vehicle can successfully do so before entering the intersection on red. An improvement in intersection pavement condition may increase the likelihood of stopping by making it easier for the driver to stop. The countermeasures detailed in the report include signal-ahead signs, advanced-warning flashers, rumble strips, left-turn signal sign and pavement surface condition.
The countermeasures presented in this section of the report are mainly intended for those violators who "push the limits" of the signal phasing or try to "beat" the yellow signal. Previous surveys indicate that the common reasons drivers speed up and try to beat a yellow light include being in a rush and saving time. Although these drivers may not have intended to violate the red signal, they did intentionally enter towards the end of the phase knowing that there was the potential that they would violate the signal. Often times, these drivers do miss the yellow and end up running the red. The countermeasures presented relate to signal timing. There are many different and specific signal countermeasures that can be implemented regarding signal timing. The range in countermeasures includes signal optimization, modifications to signal-cycle length, yellow-change interval, all-red clearance interval and dilemma zone protection.
Eliminating the need to stop at an intersection can obviously eliminate the potential for red-light running. This can be done by removing the signal or redesigning the traditional intersection. Other countermeasures in this category that are described in the report include unwarranted signals, roundabout intersection design and flash mode for signals.
The solution to the red-light running problem often involves a combination of education, enforcement and engineering countermeasures. Though the principal focus of the report is engineering countermeasures, the report also provides information on how an agency can identify the existence of a red-light running problem and then select the most appropriate countermeasure or combination of countermeasures. The report details a process for determining if a red-light running problem exists and what types of countermeasures could be implemented in a logical and systematic manner. The process respects the fact that individual agencies may already have established procedures for conducting audits and reviews of problem intersections, which may accomplish the same objective.
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