The facts are clear. Comprehensive traffic signal timing programs work. A list of just some of the proven benefits is impressive:

Timed traffic lights in Longview, WA

▪  Reduces delays
▪  Eliminates traffic congestion
▪  Reduces fuel consumption
▪  Relieves driver frustration
▪  Reduces speeding
▪  Increases pedestrian safety
▪  Improves air quality
▪  Saves cities money
▪ Reduces thru-traffic on
secondary streets

Studies after studies have quantified the benefits that traffic signal timing brings to a community.

A 1995 report from the Texas Department of Transportation concluded that a traffic light synchronization program in Texas saved drivers 20.8 million gallons of gas, 22 million hours of delay time and 729 million stops. The program covered 1,348 intersections in 43 cities and in 1995, cost $7.7 million dollars to implement. The total savings to drivers by way of fuel consumption and delays alone is estimated at $252 million in the first year. This comes out to a whopping $32.30 in savings for every dollar spent on the project!

The results obtained in Texas are no anomaly. Similar results were found by various cities across the U.S.

 ▪  In Los Angeles, a city that knows something about traffic congestion, their Adaptive Traffic Control System (ATCS) was shown to reduce travel time by 12.7 percent, cut stops by more than a third and decrease delays by 21.4 percent.

▪  California’s Fuel Efficient Traffic Signal Management Program (FETSIM) resulted in an 8.6 percent reduction in fuel use, 15 percent fewer delays and an overall 7.2 percent savings in travel time.

▪  By synchronizing the lights along an 11 intersection throughway, the city of St. Augustine, Florida realized a 36 percent reduction in delays, an annual savings of 26,000 gallons of gas and a cost savings of $1.1 million.

▪  In Portland, Oregon, city officials spent $70,000 to time 35 traffic signals and saved over 175,000 gallons of gas per year. 

Texas Transportation Institute findngs

These examples represent the good news. The bad news is that according to the United States Department of Transportation, as much as 75 percent of the traffic signals across the U.S. are not optimized for smooth traffic flow. If improvements were made, the U.S. would save about 17 billion gallons of motor fuel each year and reduce harmful emissions by up to 22 percent. A driver that commutes 2 hours to work each day would get back 50 hours of his/her life each year.

Integrated traffic signal systems (ITS) may vary but typically include several components such as an automated data collection device, a centrally controlled traffic signal synchronization system, interconnected traffic signals and adaptive signal controls. A maintenance management program ensures that traffic light synchronization is coordinated along with traffic pattern changes such a commute direction or special events. As longer-term traffic patterns change, signal timing will have to be adjusted. According to DOT, operations and maintenance typically require one traffic engineer for every 75 to 100 signals and one signal technician for every 40 to 50 signals. Retiming should be performed every two to three years at a minimum.

It’s also important that drivers understand that lights are synchronized and that they know the rate of speed they must maintain in order to hit all green lights. To accomplish this, the city of Longview, Washington, installed TrafficFlow Manager displays along their timed routes. Integrated together with the timed traffic signal system, the electronic signs automatically adjust the posted speed limit to inform drivers of the optimal speed they need to travel.

Sounds expensive? Actually, costs for entire ITS systems range from around $3,000 – $5,000 per updated signal. And as we saw in early examples, once installed, cost savings ratios are enormous – 17:1 in California; 62:1 in Texas.

So where do you start?

If you’re looking to get your local officials on board, you may want to firsts send them to this blog or to some of the linked reports. If you’re a city traffic engineer or government official, you may want to start by contacting those that can provide more information on requirements, technologies and funding.

Below are some suggested links:

Research & Innovation Technology Administration: Intelligent Transportation Systems

ITS Application Overview

FHWA Office of Operations, Arterial Management Program

National Traffic Signal Report Card

The Consortium on ITS Training & Education