All about adaptive traffic signals

Posted by on Apr 3, 2012 in Adaptive Traffic Signals | No Comments

The Birmingham News/Michelle Campbell

When the topic of adaptive traffic signals comes up, people often say, “Don’t we already have those?”

The short answer is yes, but there’s a lot more to it than that.

The Federal Highway Administration initiative known as Every Day Counts is designed to identify and deploy innovation aimed at shortening projects, enhancing safety, and protecting the environment. Sain Associates is involved in Alabama’s Every Day Counts program.  One specific area where Sain is involved is a sub-initiative known as Adaptive Signal Control Systems, which is conducting research about how adaptive systems could be a good fit for Alabama roadways.

Adaptive traffic signals react to real time traffic conditions and adjust accordingly. This is where they differ from the signals many people are familiar with.

The timing of non-adaptive signals is based on engineering studies that determine the best way to time the signal based on traffic data that was collected in a small snippet of time. That period of time could have been two, five, 10 or even 20 years ago. These signals don’t generally adapt to big changes in traffic flow.

An adaptive signal, on the other hand, has computers that constantly monitor traffic. This allows them to adjust as they make calculations and complete algorithms based on real-time traffic conditions. They are a lot smarter and faster than any of us.

The technology isn’t really new, but it’s catching a new wave of interest in the US, and we’re starting to see it more and more as people look for new solutions to traffic issues.

With reduced funding levels for national infrastructure, many agencies are in maintenance mode instead of build mode trying to get the most out of what they already have. That means there’s a lot of retrofitting to get existing roads up to current standards – the mindset of widening your way out of congestion is not quite as trendy these days.

Optimizing traffic signals falls into this category because it involves looking for new solutions to help manage roadways that already exist.

Next week, we’ll share some examples of when and where adaptive signals can be most beneficial.

Sain Associates, Inc., is headquartered in Birmingham, Alabama, with offices in Cullman, Alabama, 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.


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