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Optimizing Performance Mobility & Safety—Making Work Zones Work Better:
Work Zone Automated Speed Enforcement Program

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United States Department of Transportation logo.

U.S. Department of Transportation
Federal Highway Administration
Office of Operations
1200 New Jersey Avenue, SE
Washington, DC 20590


Fall 2017

Automated Speed Enforcement (ASE) systems, consisting of traffic enforcement cameras, photo enforcement programs, or speed cameras, are used to more strictly enforce speed limits in work zones. ASE systems help improve work zone safety by identifying drivers who exceed the posted speed limit by a certain amount, who are then issued citations. Use of ASE systems is especially beneficial at work zones in high-speed areas. ASE systems typically include signage, placed well before the speed camera installation, clearly indicating that ASE systems are in use and specifying the lowered speed limit. Agencies are highly encouraged to deploy a speed display trailer informing drivers of their vehicles' speed as they enter the enforcement area.

This photo shows a work zone speed limit sign which displays a speed limit of 55 miles per hour and indicates that the speed limit is photo enforced.

Source: Maryland Safezones

ASE systems in work zones function similarly to permanent speed camera installations used in many jurisdictions to enforce speed limits through automatic citations. These permanent setups are unmanned and often installed near schools or roads with high crash or fatality rates. Important differences include the permanence of the equipment and, in most cases, the requirement that vehicle mounted work zone ASE systems be continuously manned during operation. The permanent installations are often used in lower speed settings, while the work zone ASE systems are only recommended for roadways with a posted speed limit of 45 mph or higher.

This image, from the Maryland Safezones program, notifies drivers that speed limits are photo enforced with automated cameras in the work zone.

Source: Maryland Safezones

What Are Its Primary Benefits?

ASE systems help in slowing down traffic prior to the work zone which enhances both motorist and construction crew safety. The advance warning signs recommended for these systems alerts drivers to the upcoming work zone and the reduced speed limit associated with it. These systems have been shown to significantly reduce the number of drivers exceeding the posted speed limit, the number of crashes in the work zone and the number of injuries and fatalities due to crashes in the work zone.

This is an illustration of a speed display trailer, which shows drivers both the posted speed limit in the work zone and their own detected speed via a two digit amber light-emitting diodes (LED) display.

Source: Maryland Safezones

While there has been occasional public backlash against the use of speed cameras in some locations, the use of ASE systems in work zones is widely supported by the public. (University of Minnesota, Center for Excellence in Rural Safety.) Overall, the program has proven to be very effective at obtaining voluntary compliance to the speed limits from most drivers.

Where Are Work Zone ASE Systems Effective?

ASE systems can be considered in the following circumstances:

  • There is an active work zone on an expressway or controlled access highway (speed limit of 45 mph or higher).
  • Workers are exposed or there are motorist hazards (lane shifts, lane splits, lane width reductions, closed shoulders, rough pavement, etc.)
  • The work zone will remain active over a long period of time.
  • There are no significant obstructions to line of sight for the speed camera.

This image is an example of the speed limit violation citations that are issued through the Maryland Safezones automated speed enforcement program. The citation contains the photos of the car violating the speed limit, information on the car's detected speed and the posted speed limit, explanatory text on the nature of violation, and a section that can be cut out and sent in the mail to pay the citation.

Source: Maryland Safezones

Considerations When Deploying ASE Programs

  • Warning signs should be placed well before drivers arrive at the work zone to inform them that an ASE system is in use.
  • In most cases the systems must be continuously manned during deployment.
  • The vehicle mounted setup should be placed behind a protected area (preferably behind a barrier or guiderail, otherwise behind a traffic control device or on the shoulder).
  • The grade of the roadway and any other features must not impair visibility of the setup.
  • Legislation may be required to authorize the use of ASE systems in some jurisdictions.
  • ASE systems are not intended to replace other work zone safety operations.
  • Because each construction project differs, the selection, application and location of these devices should be determined on a project-by-project basis.

This photo shows a vehicle that is used as part of the Maryland Safezones automated speed enforcement program.

Source: Maryland Safezones


Implementation of an ASE system in Maryland has resulted in a significant increase in work zone safety. In addition to an 80 percent reduction in speeding violations, as shown below, fatalities have dropped by half in the three years since the Maryland program's inception.

This chart shows the overall violation percentages found by the Maryland Safezones program (the percent of vehicles exceeding the enforcement speed). In July of 2010, approximately 7 percent of vehicles exceeded the enforcement speed. This dropped to between 0.8 and 1.5 percent in the months measured in 2013 (January, April, and August) – signifying an approximately 80 percent reduction in speed violations from 2010 to 2013.

Source: Maryland Safezones

To learn more, contact:

Kayode Adenaiya
Office of Traffic & Safety
Maryland SHA
(410) 787-5864

Priscilla Tobias
Bureau of Safety
Illinois DOT
(217) 782-3568

Steve Haapala
State Work Zone Engineer
Washington DOT
(360) 705-7241

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