Jeff Stephenson, P.E., is the Team Leader of [...]
All of this can potentially be done with proper signal timing and coordination. If signals aren’t timed or coordinated properly, vehicles will likely have to make frequent stops while traveling through a corridor. This wastes time and fuel, creates congestion and pollution and frustrates drivers. The sensitivity of traffic signal controller settings can be an issue as well. One wrong setting can have a huge impact and cause the traffic signal to operate inefficiently.
Proper signal timing is also beneficial for cities and towns, as the reduction in congestion often makes their streets more appealing and easier to navigate. Businesses along properly timed signalized corridors can benefit as well, since many people avoid heavily congested areas when they are out and about.
Despite the benefits, many signal systems are not operated or managed as well as they could be. The National Transportation Operations Coalition releases a National Traffic Signal Report Card to assess traffic signal systems across the nation. Assessments are conducted by U.S. agencies to grade themselves. The overall grade of the 2012 report card was 69, a D+. Although the grade has improved since the first report card was released in 2005, it is still generally unacceptable in the eyes of the public. There are many reasons for such a low grade, but lack of funding and manpower to maintain and improve the quality of signal operation across the nation tops the list. It is recommended that signal timings be updated every 2-5 years to accommodate changes in traffic levels or traffic patterns. When this does not happen, the effectiveness of the signal timings may deteriorate and cause congestion and delay.
Signal timing and coordination projects often provide a lot of bang for the buck. They typically have a very high benefit to cost ratio that can be anywhere from 2:1 to as much as 50:1. We believe working on signal timing projects allows us to really make a difference.
With some projects, signal timing and coordination is the main objective and our sole focus. In other cases, signal timing and coordination is often addressed as part of a larger scale project such as a roadway widening, resurfacing or access management project.
Adaptive traffic signal systems often require more front end analysis, but they are becoming more popular based on their ability to “adapt” or analyze traffic volume pattern changes in “real time” and adjust signal timings and coordination settings accordingly.
On projects where we have implemented signal timings, we like getting feedback from those that drive the route every day. We do this by contacting the local transportation officials or monitoring media outlets. For example, once we were tweaking the signal timings we had just implemented on a project, and while we were at the project site listening to a talk show on a local radio station, a caller commented about the improvements to the signal timing on that same corridor!
We have found that the driving public is generally very perceptive of signal timing and quickly notices changes, good or bad. And it makes sense. Many people between the ages of 18 and 65 drive the same stretch of road four or more days each week at the same times each day. Traffic signals are often an element of that daily commute.
It is very gratifying to be able to deliver a relatively low cost project that results in substantial environmental improvements, and in many cases, quality of life enhancements.
Sain Associates, Inc., is headquartered in Birmingham, Alabama, with offices in Pulaski, Tennessee and Mandeville, Louisiana. Sain is a site engineering, traffic/transportation engineering and planning and land surveying firm with experience in more than thirty states.