Beware of the likely trade-off between a decrease in the frequency of right-angle crashes and an increase in the frequency of rear-end crashes when considering installation of red-light-cameras.

Experience from a national evaluation of red-light cameras

April 2005
Baltimore,Maryland,United States; Charlotte,North Carolina,United States; Howard County,Maryland,United States; California,United States

Background (Show)

Lesson Learned

Red-light running is a significant safety problem in the United States, resulting in approximately 95,000 crashes and 1,000 fatalities annually. One ITS treatment option is to install red-light cameras as a means of deterring drivers from running red lights. Jurisdictions weighing the costs and benefits of installing RLC can gain insight from a national study of RLC. The study, based on a robust sample of RLC treatment sites, offers recommendations on deployment as well as data on the benefits and costs of RLC. Key insights from the report include the following.
  • Be mindful that RLC treatment sites are associated with a decrease in the frequency of right-angle crashes but an increase in the frequency of rear end crashes. This outcome from the 132 sites suggests that RLC as a safety intervention should be used for intersections that experience a high number of right-angle crashes compared to rear end crashes. The results also suggest that RLC should be considered for intersections that have: 1) a high ratio of right-angle crashes to rear end crashes, 2) a higher proportion of entering Average Annual Daily Traffic (AADT), 3) shorter cycle lengths and intergreen periods, and 4) one or more left turn protected phases.
  • Install warning signs at RLC intersections and city limits, and follow through with a good public information program on intersection safety. The presence of RLC warning signs enhances the benefits delivered by the RLC system itself. This effect is similar to the “spillover” effect in which nearby non-RLC intersections realize benefits. In addition to signage, high profile messaging through press releases, briefings and events are powerful ways to inform the public of new RLC installations. In fact, higher levels of publicity were associated with greater RLC benefits than were medium levels of publicity.
  • Bear in mind that the economic benefit of RLC may be modest but it is still important. The benefits from cost savings obtained at RLC sites by the decrease in right-angle crashes can be partially offset by the higher costs from the increase in rear-end crashes. However, the net economic benefit per treated site per year ranges from $39,000 for property-damage-only (PDO) crashes to $50,000 when PDO crashes are excluded.
The effect of RLC on the frequency of crashes varies by crash type, in which the number of right-angle crashes decrease and the number of rear end crashes increase. Therefore, RLC is most effective for intersections that have fewer rear end crashes compared to right-angle ones. To increase the effectiveness of RLC deployment, select appropriate intersections for installation and conduct a good public information campaign to inform the public of the benefits and purpose of RLC.

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Safety Evaluation of Red-Light Cameras

Author: Forrest M. Council; Bhagwant Persaud; Kimberly Eccles, Craig Lyon, Michael S. Griffith

Published By: ITS Joint Program Office and Office of Safety Research and Development Federal Highway Administration

Source Date: April 2005

EDL Number: 14270

Other Reference Number: FHWA-HRT-05-048

URL: https://rosap.ntl.bts.gov/view/dot/4081

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Lesson of the Month for September, 2010 !


United States

Systems Engineering

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Detailed Design

Goal Areas



CCTV, closed circuit television cameras, road monitoring, sensors, vehicle detector, traffic detection, traffic monitoring, congestion monitoring

Lesson ID: 2010-00528