Automated Red Light Running Detection Program

The Department of Public Works serves as the Traffic Signal Engineering arm of the Police Department in the Automated Red Light Enforcement Program. We work with the Police in selecting candidate sites by reviewing accident types and frequency, traffic volume and engineering constraints. Prior to selection of a site for automated enforcement, we review the length of amber provided by the signal to insure conformance to all national, state and local guidelines and insure proper coordination with adjacent signals if the candidate site is in a coordinated signal system.

Automated Red Light Detection

by C. Edward Walter,
Chief (Retired), Traffic Engineering Division; Member of ITE

When the traffic signal turns red, drivers stop. Or do they? There is a growing body of evidence that many drivers don't. Perhaps congestion, impatience and reckless driving all contribute to the growing problem of drivers deliberately running red traffic signals. Researchers have found that 22 percent of urban crashes resulted from drivers running traffic controls. This was the largest single type of crash. Drivers running through red lights constitute a major portion of intersection crashes¹.

Enforcing traffic signal compliance in urban areas using police officers presents special problems. Traffic pursuits can be dangerous to police and other motorists. Additionally, there is the problem of allocating police resources to ticket red light runners. Fortunately, red signal compliance can be automated. Photo technology to enforce traffic regulations has been in use for the past 30 years worldwide. Its use has contributed to a dramatic reduction in the number and severity of traffic collisions in Europe, Australia and South Africa. In 1993, New York City began a red light running detection campaign with the installation of cameras at 15 signalized intersections. In a year, 175,000 violation notices were processed. The number of violations at each location decreased by an average of 21percent.

Howard County, Maryland, has become increasingly concerned about the number of accidents and fatalities caused by red light violations, locally as well as nationwide. Knowing of the New York City experience, the county requested and received a grant from the Federal Highway Administration to evaluate the effectiveness of automated detection in a suburban area. A consultant was employed to do a state-of-the-art evaluation of detection methods and to help the county implement a system.

Technology

Red light running cameras provide detection for one intersection approach. The camera system is connected to the traffic signal system controller and monitors the red, yellow and green phases of an approach. The camera system is also connected to loops or piezoes in the road to detect vehicle presence and speed. After onset of the red phase, a vehicle traveling over the detectors will activate the camera, causing it to take two photographs. Time since the beginning of the red phase and speed can be varied with a camera system to provide a grace period and to differentiate vehicles attempting to stop or turn right on red from those that are clear violations. For example, in Howard County the camera is not triggered unless a violation occurs 3/10* of a second or more after the signal turns red and the vehicle is traveling more than 19 mph*. The resulting photographs clearly show the front of the vehicle at the stop bar before entering the intersection; 6/10 of a second later a second photograph shows the vehicle in the intersection. Using color photography, it is easy to see that the traffic signal is red. Superimposed on each photograph is the date and time of the violation, together with the number of seconds since the signal turned red and the speed at which the violation occurred. Additional identifying information is also shown.

The existing camera technology works exceedingly well and is extremely reliable. There are five major manufacturers of red light camera equipment. Three of the manufacturers are in Europe, one is in South Africa, and one in the United States. Howard County is using the Dutch Gatsometer, which is represented in the United States by U.S. Public Technologies. The Gatsometer unit consists of a dedicated computer and removable industrial robot camera with a 100 foot film pack. The unit, which includes a built-in flash, fits in a special housing a top a hinged pole. Some other manufacturers use a fixed pole while American Traffic Systems provides an automatic elevator pole adapted from a garage door opener.²

All of the camera systems use bulk loaded 35mm film and are available with different lenses, depending on placement of the camera unit and the number of lanes to be monitored. Special loop detectors are placed in the roadway and run directly to the computer/camera assembly, which includes detector amplifiers. Depending on location, the built-in flash unit can be combined with a separate slave flash unit mounted close to the intersection.

Selecting proper locations for a red light camera is critical. In Howard County, we began by examining accident data with particular emphasis on angle accidents. Intersection plans were examined, followed by field review, and if the intersection appeared to be a worthwhile candidate, a specially modified traffic counter manufactured for us by Mitron Corporation was used, which only counted vehicles crossing during the red phase. The counter was set up with an initial delay of 3/10 of a second, corresponding to the proposed automated detector device. Likewise, only vehicles entering the intersection at speeds greater than 20 mph were tabulated. Candidate intersections should have 30 or more violations per day to justify the cost of installation and operation.

Police Partnership

Automatic red light detection requires a partnership between the police department and traffic engineering. We can evaluate camera systems and choose locations to be monitored, but it ultimately becomes the police department's responsibility to operate the cameras, process the film and prepare the notices of violation. In a demonstration program, the number of violations may be manageable for processing in-house. However, in a full scale operation with 10-20 cameras operating and with each camera catching 30-40 violators a day, the situation can quickly overwhelm the capabilities of a police department. In New York City, Electronic Data Systems Corporation services the cameras, processes the film, and prepares the notices of violations under contract with New York City. The violation notices are reviewed and signed by a police department representative. The sheer volume of data that accumulates and must be available in the event of court trials requires establishment of a record keeping system with quick recovery capability. Although a small percentage of violations come to trial, the data for those which do must be available for the judge's perusal. In New York City, the photographs are digitized and stored on central computers and the judges have remote computer and monitor capability to retrieve and examine the data.

It appears obvious that a close partnership is required between the police and traffic engineering during all phases of the red light camera detection operation. In Howard County, a representative of the Police Department worked closely with the Traffic Engineering Division as the program moved forward. With the project into the implementation phase, the police have assumed the dominant role while traffic has retained the technical location and interface aspects.

Enabling Legislation

Under most State law, moving violations require the apprehension and issuance of a ticket to the driver of a motor vehicle. If the driver elects to appear in court, the officer must testify that this person was the driver of the motor vehicle and the driver was the person who signed the violation ticket.

Automatic detection of red light runners will generally require changes to motor vehicle laws to charge the vehicle owner, not the driver. The typical camera installation photographs the vehicle from the rear and the driver and passengers cannot be seen, much less identified. The generally accepted change, and what we did in Maryland, was to treat automated detection of red light violators in a manner similar to a parking offense. The vehicle owner is charged, a fine is imposed and no points are involved. New York City got a special local law from the General Assembly³ with a sunset provision in it, which permitted the City to send violation notices and prosecute red light runners in this fashion. In Maryland, the 1997 State Legislature approved a statewide law without a sunset provision. It became effective in October 1997.

Future Developments

Timely issuance of notices of violations for red light runners is imperative. This requires that the cameras be serviced frequently, perhaps daily. Issuance of a notice of violation is manpower intensive and costly. Fortunately, new technology is becoming available to reduce costs and speed processing of violation notices.

Film technology is being replaced with digital technology. Digital cameras are already available from Kodak and several Japanese manufacturers. The availability of digital cameras means that images can be transmitted to a central location where they can automatically be printed onto a notice of violation. The digital pictures taken by a system can be stored internally or retrieved remotely using modem telephone connections or wireless radio. This type of system allows electronic storage and retrieval with a minimum of manpower. It is ideally suited for the large data base operation required for processing red light running violations. We are working under a federal grant to demonstrate the feasibility of digital based red light running detection systems. We have identified plausible technology and begun the installation of systems at four sites from vendors in Australia, France, Great Britain and Israel.

Optical character recognition, which is available today, could be a natural adjunct to digital photography and permit automated processing of license plate numbers for identification of owners and their addresses. This would further reduce manpower requirements.

Automated red light running detection is a rapidly developing field that could provide an important tool for improving highway safety. It also helps cement the natural partnership between police enforcement and traffic engineering.

*Note: As variations in geometrics and approach speeds are encountered the default value of 0.3sec may be reduced to 0.1sec or increased to 0.4sec. Default speeds may be reduced to 12mph or increased to 21mph.

Bibliography

• Retting and Williams, "Characteristics of Red Light Violations: Results of a Field Investigation," Insurance Institute for Highway Safety, October 1994.
  
  
• "Technology Assessment; Automated Traffic Signal Violation Detection and Enforcement Systems," Electronic Data Systems, August 17, 1995.
  
  
• State of New York, Senate Assembly Bill S550-D, A 923-D, January 13, 1987.