A violation occurs when a motorist enters an intersection some time after the signal light has turned red. Motorists inadvertently in an intersection when the signal changes to red (waiting to turn left, for example) are not red light runners.

A nationwide study of fatal crashes at traffic signals in 1999 and 2000 estimated that 20 percent of the drivers involved failed to obey the signals.¹ In 2006, almost 900 people were killed and an estimated 144,000 were injured in crashes that involved red light running. About half of the deaths in red light running crashes are pedestrians and occupants in other vehicles who are hit by the red light runners.

Motorists are more likely to be injured in urban crashes involving red light running than in other types of urban crashes. Institute researchers studied police reports of crashes on public roads in four urban areas during 1990-91. Occupant injuries occurred in 45 percent of red light running crashes, compared with 30 percent of other crash types.²

Red light running crash

A study conducted during several months at five busy intersections in Fairfax, Virginia, prior to the use of red light cameras found that, on average, a motorist ran a red light every 20 minutes at each intersection.³ During peak travel times, red light running was more frequent. Analysis of red light violation data from 19 intersections (without red light cameras) in four states found that 1,775 violations occurred over 554 hours, for a violation rate of 3.2 per hour per intersection.⁴

The Institute created a profile of red light runners by studying driver behavior at an Arlington, Virginia, intersection equipped with a red light camera. The 1996 study compared red light runners with motorists who had an opportunity to run a red light but did not. As a group, red light runners were younger, less likely to use safety belts, had poorer driving records, and drove smaller and older vehicles than drivers who stopped for red lights. Red light runners were more than three times as likely to have multiple speeding convictions on their driver records. No gender differences were found between violators and drivers who did not run red lights.⁵ A 2007 study in Sacramento, California, found about 30 percent of red light runners were under 30 years of age.⁶

Red light cameras can help communities enforce traffic laws by automatically photographing vehicles whose drivers run red lights. A red light camera system is connected to the traffic signal and to sensors that monitor traffic flow at the crosswalk or stop line. The system continuously monitors the traffic signal, and the camera is triggered by any vehicle entering the intersection above a preset minimum speed and following a specified time after the signal has turned red. Violations occurring within 2/10ths of a second after the signal changes to red generally aren't recorded because of technical limitations of the recording equipment. In addition, many red light camera programs provide motorists with grace periods of up to 1/2 second. Depending on the particular technology, a series of photographs and/or video images show the red light violator prior to entering the intersection on a red signal, as well as the vehicle's progression through the intersection. Cameras record the date, time of day, time elapsed since the beginning of the red signal, vehicle speed, and license plate. Tickets typically are mailed to owners of violating vehicles, based on review of photographic evidence.

Red light camera violation photo

Enforcing traffic laws in dense urban areas by traditional means poses special difficulties for police, who in most cases must follow a violating vehicle through a red light to stop it. This can endanger motorists and pedestrians as well as officers, and police cannot be everywhere at once. Traffic stops in urban areas can exacerbate traffic congestion. Communities do not have the resources to allow police to patrol intersections as often as would be needed to ticket all motorists who run red lights. Red light cameras allow police to focus on other enforcement needs.

Cameras have been shown to substantially reduce red light violations. Institute evaluations in Fairfax, Virginia, and Oxnard, California, showed that camera enforcement reduced red light running violations by about 40 percent.^3,7 In addition to reducing red light running at camera-equipped sites, violation reductions in both communities carried over to signalized intersections not equipped with red light cameras, indicating community-wide changes in driver behavior. An Institute evaluation of red light cameras in Philadelphia, Pennsylvania, found that after red light violations were reduced by 36 percent following increased yellow signal timing, the addition of red light cameras further reduced red light violations by 96 percent.⁸

In addition to reducing red light violations, cameras have been shown to reduce intersection crashes. In Oxnard, California, significant citywide crash reductions followed the introduction of red light cameras, and injury crashes at intersections with traffic signals were reduced by 29 percent.⁹ Front-into-side collisions — the crash type most closely associated with red light running — were reduced by 32 percent overall, and front-into-side crashes involving injuries were reduced by 68 percent. An Institute review of international red light camera studies concluded that cameras reduce red light violations by 40-50 percent and reduce injury crashes by 25-30 percent.¹⁰

Some studies have reported that while red light cameras reduce front-into-side collisions and overall injury crashes, they can increase rear-end crashes. Because the types of crashes prevented by red light cameras tend to be more severe than rear-end crashes, research has shown there is a positive aggregate benefit. A recent study sponsored by the Federal Highway Administration evaluated red light camera programs in seven cities.¹¹ The study found that, overall, right-angle crashes decreased by 25 percent while rear-end collisions increased by 15 percent. Results showed a positive aggregate economic benefit of more than $18.5 million over 370 site years, which translates into a crash reduction benefit of approximately $39,000 per site year. The authors concluded that the economic costs from the increase in rear-end crashes were more than offset by the economic benefits from the decrease in right-angle crashes targeted by red light cameras. Not all studies have reported increases in rear-end crashes. The Cochrane Collaboration (an international organization that conducts systematic reviews of the scientific literature on public health issues) reviewed 10 controlled before-after studies of red light camera effectiveness in Australia, Singapore, and the United States.¹² Using techniques of meta-analysis, the authors estimated a 16 percent reduction in all types of injury crashes and a 24 percent reduction in right-angle crashes. The review did not find a statistically significant change in rear-end crashes.

While the provision of adequate yellow signal timing is important and can reduce red light running, longer yellow timing alone does not eliminate the need or potential benefits of red light cameras. Studies have shown that increasing yellow timing to values associated with guidelines published by the Institute of Transportation Engineers¹³ can significantly decrease the frequency of red light violations.^14,15,16 In addition, a 2002 Institute study of modified yellow and all-red traffic signal timing at urban intersections reported that injury crashes were reduced by 12 percent at experimental sites relative to comparison sites.¹⁷

An Institute study conducted in Philadelphia, Pennsylvania, evaluated incremental effects on red light running of first lengthening yellow signal timing, followed by introduction of red light camera enforcement.⁸ Yellow signal timing was increased by about one second at two intersections where red light cameras were installed. Results show that while increased yellow signal timing reduced red light violations by 36 percent, the addition of red light camera enforcement further reduced red light violations at these sites by 96 percent beyond levels achieved by the longer yellow signal timing.

No. Cameras are set so that only those vehicles that enter an intersection after the light has turned red are photographed. Vehicles that enter on yellow and are still in an intersection when the light changes to red are not photographed. This technology is intended to identify vehicles driven by motorists who enter an intersection after the signal has turned red.

Yes. Trained police officers or other officials review every picture to verify vehicle information and ensure the vehicle is in violation. Tickets are mailed to vehicle owners only in cases where it is clear the vehicle ran a red light.

No. Driving is a regulated activity on public roads. By obtaining a license, a motorist agrees to abide by certain rules, such as to obey traffic signals. Neither the law nor common sense suggests drivers should not be observed on the road or have their violations documented. Red light camera systems can be designed to photograph only a vehicle's rear license plate, not vehicle occupants, depending on local law. Only vehicles driven by motorists who violate the law are photographed.

More information on legal issues

Before cameras may be used for law enforcement, laws must authorize enforcement agencies to cite red light violators by mail. The legislation must make the vehicle owner responsible for the ticket, establishing a presumption that the registered owner is the vehicle driver at the time of the offense. This can be accomplished either by state statutes or in some states by local legislation. Red light cameras currently are authorized in about half of US states. Depending on state law, violations photographed by red light cameras are commonly treated in one of two ways — as traffic violations or as the equivalent of parking tickets. If, as in New York, red light camera violations are treated like parking citations, the law can make registered vehicle owners responsible without regard to who was driving at the time of the offense.

Camera equipment costs vary based on the type of camera, complexity of the intersection, and technical requirements. A red light camera system with installation costs approximately $100,000. A single red light camera can be used at several locations once the sites are equipped to work with the camera, allowing communities to move cameras among sites without drivers knowing which ones are active at any given time. Startup costs can be offset by fines, savings from crashes prevented, and by freeing police to focus on other enforcement efforts.

No. The objective of photo enforcement is to deter violators, not to catch them. Signs and publicity campaigns typically warn drivers that photo enforcement is in use. Revenue is generated from fines paid by drivers who continue to run red lights, but this is a fundamental component of all traffic enforcement programs. Independent audits of red light camera enforcement have found that these programs generally do not generate excess revenue. For example, the California state auditor reported in 2002 that red light cameras were not generating large amounts of revenue.¹⁸ The financial status of only two of the state's seven camera programs was break-even or better. The US General Accounting Office reported in 2003 on the contribution of federal funds to local use of photo enforcement technology and the amount of revenue generated by these programs.¹⁹ The report found that photo enforcement program revenues were lower than program costs in three jurisdictions, while the revenues in two other jurisdictions exceeded program costs.

The large majority of the US public supports red light cameras. A 2000 Institute survey in ten cities — five with cameras and five without — reported that more than 75 percent of drivers supported camera enforcement.²⁰ A 2002 nationwide survey sponsored by the National Highway Traffic Safety Administration and conducted by the Gallup Organization found that 75 percent of drivers favored the use of red light cameras.²¹ A 1996 survey by the Insurance Research Council found that the highest support for red light cameras was in large cities, where 83 percent of respondents supported their use, compared with 52 percent of respondents in suburbs.²²

Cameras are used for law enforcement in Albuquerque, Atlanta, Baltimore, Chicago, Denver, Houston, Los Angeles, New York City, Philadelphia, Phoenix, San Diego, San Francisco, Seattle, and Washington, DC, plus many smaller communities.

US cities with red light cameras

Red light cameras have been used in at least 33 foreign countries since the 1970s.²³ Countries that use red light cameras include Australia, Austria, Belgium, Canada, Germany, Israel, the Netherlands, Singapore, South Africa, Switzerland, Taiwan, and the United Kingdom.