Rules of the Road

It’s not the timing of the lights causing traffic congestion; there are too many cars

City of Bellingham traffic operations engineers monitor traffic signal actions in really time, and if necessary, they make real-time adjustments to traffic lights to control traffic flow. They usually reserve that ability for unexpected events, such as a crash that blocks traffic.
City of Bellingham traffic operations engineers monitor traffic signal actions in really time, and if necessary, they make real-time adjustments to traffic lights to control traffic flow. They usually reserve that ability for unexpected events, such as a crash that blocks traffic. Courtesy to The Bellingham Herald

Question: Have the traffic lights in Bellingham been professionally set up, that is adjusted to allow for the best flow of traffic? I do not understand how the city doesn’t have the ability to have the lights synchronized on some of our busiest roads.

Answer: This question is adapted from a stack of questions about signal timing in Bellingham. The top three locations where drivers get frustrated by traffic lights are, in order, Sunset Drive, Guide Meridian and Lakeway Drive. Sunset Drive has a dominating lead in the complaint column.

I didn’t know much about the details of managing traffic signals, so I set up a meeting with Steve Haugen, a traffic operations engineer for the city. He brought me into mission control (that’s what I called it) where I saw a wall of screens filled with live feeds of Bellingham intersections and computer monitors displaying traffic signal actions in real time. If necessary, the traffic engineers can make real-time adjustments to traffic lights to control traffic flow. They usually reserve that ability for unexpected events, such as a crash that blocks traffic.

When I said I was there to discuss traffic signal timing, Steve smiled knowingly and mentioned Sunset Drive. He pointed out that it’s the first video feed on their monitor. The traffic engineers in Bellingham know Sunset Drive is a problem; they’ve heard the complaints from drivers, they see the video feeds of traffic backing up and one of them travels daily on Sunset Drive to get to work. It hasn’t been ignored; they’ve applied a lot of tools and resources to try to solve it.

When we talk about signal timing, the answer I think everybody hopes to hear is, “We’ll just make a little adjustment to the lights and everything will be fine.” Unfortunately, that’s not the case. If there were a simple solution, they’d have solved it by now.

Bellingham, like many other cities, uses traffic modeling software called Synchro. With Synchro, traffic engineers can simulate actual traffic conditions and see how changes to signal timing would impact traffic efficiency. This industry-standard software also is used by Washington State Department of Transportation.

With I-5 exiting onto Sunset Drive, Bellingham and WSDOT have an interest in getting these signals right. By collaborating and using the best tools available, they’ve reached a conclusion: There are too many cars on Sunset Drive.

Signal timing can’t compensate for traffic volume that exceeds the capacity of the roads. Once roads reach their saturation point, adjustments to traffic signals can’t really improve the problem. Instead, it just shifts the problem around. Expediting traffic flow in one direction creates backups in another.

A traffic engineer constantly works to balance efficiency and safety. On Sunset Drive, increasing the time that lights stay green for east and westbound traffic would result in backups for vehicles wanting to get onto Sunset. That would include the I-5 offramps.

From a safety perspective, that’s the most dangerous scenario, because it increases the possibility of a high-speed rear-end crash if traffic backs up onto the freeway. During peak traffic time the lights have to be timed to move traffic off the freeway fast enough to avoid that scenario.

While Sunset Drive might be the worst offender, too many cars is a problem on many of our roads, not just in Bellingham but across the state. It appears that our population is growing faster than the infrastructure we’re building to support it. Given all the technology available to manage traffic signals, if you encounter intersections with signals that seem poorly timed, the most likely explanation is actually that the roads can’t handle the volume of traffic.

Road Rules is a regular column on road laws, safe driving habits and general police practices. Doug Dahl is the Target Zero Manager for the Whatcom County Traffic Safety Task Force. Target Zero is Washington’s vision to reduce traffic fatalities and serious injuries to zero by 2030. For more traffic safety information visit TheWiseDrive.com. Ask a question.

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