The U.S. Department of Transportation's Federal Highway Administration has made available a new video demonstrating that re-timing of highway signals can better manage congestion and a growing traffic demands. It has been estimated that more than 75% of traffic signals can be made more efficient and safer by updating or retiming equipment.

The video, "It's About Time, Traffic Signal Management: Cost-Effective Street Capacity and Safety" shows how proper signal timing can improve air quality and reduce fuel consumption; decrease traffic congestion and save time for commercial and emergency vehicles; and reduce aggressive driving behavior and the number of accidents.

What is Traffic Signal Management?

Traffic Signal Management is taking the existing traffic signal equipment already in place and using available tools, techniques, and in some cases improved equipment to more efficiently utilize our city streets and signal systems.

Traffic signal management is one of the most cost-effective ways to help traffic move and make our streets safer and can have several benefits when put in place:

1. Improves air quality and reduces fuel consumption

2. Reduces congestion, saves time for commercial vehicles, emergency vehicles, buses and the public.

3. Reduces the number of severe accidents

4. Reduced aggressive driving behavior

5. Postpones or eliminates the need to construct additional capacity

Traffic Signal Management Techniques

There are many traffic signal management techniques, including:

1. Removing unneeded signals. This will both improve traffic flow and reduce maintenance costs.

2. Studying the signalized intersection to produce a new timing plan that will more efficiently use the available time.

3. Developing and implementing additional signal timing plans to account for changes in traffic flow.

4. Adding traffic detectors to minor side streets, which enables traffic progression through the signal system.

5. Including protected turn phases can improve safety.

6. Installing new and improved signal equipment such as solid state electronic controllers. This can provide additional capability to implement more advanced traffic control techniques, and will improve system reliability while reducing maintenance costs.

7. Using computer programs to design and develop proper signal timing.

8. Controlling signals from a central location enables remote management without visiting the actual intersection.

9. Coordinating signal operations across jurisdictional boundaries is an excellent way to provide motorist with seamless traffic flow.

10. And perhaps, most importantly, installing and maintaining equipment properly is key to actively managing the efficient operation of intersections.

A Primary Traffic Signal Management Technique:
Signal Re-timing

So when do you need to conduct a signal re-timing project? Several changes to signalized intersections warrant the re-timing of traffic signals.

1. When a new signal is added or a signal is updated.

2. When traffic or pedestrian volumes, or turning movements change significantly.

3. When access to a roadway changes.

4. And when there is a change in the geometry of a roadway.

Signal re-timing should be considered no less than every three years. More often is desirable. It should take around 20 to 25 staff hours per intersection. A general rule of thumb is that it will take one traffic engineer to properly operate and maintain every 75 to 100 signals and one signal technician to operate and maintain every 40 to 50 signals. Often consultants are used to supplement staff.

Traffic signal re-timing costs are relatively small and generally range around $500 to $3000 per intersection. Benefit cost ratios of up to 40 to 1 can be produced by retiming. Traffic signal management programs are eligible for federal funding.

For more information, or to obtain a copy of the video, email pam.crenshaw@fhwa.dot.gov.

Additional Resources:

Cornell Local Roads Program