For years, several states have invested in traffic signal coordination technology in order to cheaply and quickly reduce traffic congestion. Signal coordination enables a cascading "green wave" of lights, which allows greater vehicle throughput and less unnecessary stops. By placing vehicles in orderly platoons, signal coordination allows traffic engineers to manage speeds and increase mobility and safety for everyone. 

Last year, Kansas City voted to install a trial system on one of their most congested roadways not only to reduce traffic delays, but to also reduce emissions from the gridlocked cars by up to 30%.

The city of Round Rock, Texas is also working to connect and streamline its traffic lights in a similar fashion.

in Washington, the city of Bellevue lead the way in installing adaptive traffic signals on every single intersection in the city, reducing delays as much as 43% at some intersections. 

We see this across the nation as transportation departments realize it’s a relatively cheap way to get people moving.

Given the cost effectiveness and relative ease of implementing this change – what is our own state’s Department of Transportation (WSDOT) doing to help?

Well, nothing. In fact, they are designing systems to make things worse.

WSDOT’s own traffic light design guidelines don’t require interconnection or coordination. In fact, in the state’s 2017 “Transportation Efficient Communities” document, officials identify signal prioritization that helps transit as the only kind of signal coordination technology they would consider useful.

WSDOT officials oppose relieving congestion, and instead prefer to manage or shift demand by pushing people to pay tolls or take transit. This approach supports WSDOT’s goal of reducing the number of miles people travel through the trips they take. This is a subtle, but very different, goal and it creates a very different result.

The stated goal of WSDOT commute trip reduction is to:

“achieve substantial reductions in the proportion of single-occupant vehicle commute trips and the commute trip vehicle miles traveled” – RCW 70.94.537

Since WSDOT’s policy goal is to reduce trips, it is effectively counter-productive for the agency to relieve congestion to make driving more convenient and productive. In other words, the only way WSDOT can achieve their backward objective is to make traffic congestion worse. 

Innovative solutions, such as those in Texas and Kansas, are not likely to be considered by WSDOT on a wide scale as they would improve traveler throughput.

It’s not all doom and gloom though. There are categories of vehicles that WSDOT does want to move quickly.

For example, WSDOT has systems in place to allow transit to ‘jump ahead’ at traffic intersections. Most buses can hold a light green as they approach. Not only does this create more congestion on cross streets, but it also causes additional light synchronization with surrounding intersections. (For those astute readers, following a bus as it approaches an intersection has some advantages).

In Snohomish County, the new Green Swift Line adds to driver frustration. Community Transit added bus stops into the flow of traffic and on the corners of busy intersections. This helps the bus avoid having to wait to pull back into traffic, but creates a dangerous situation where cars get backed up, sometimes in the intersection, and must try to drive around the bus. The 200 buses on the route per day carry an average of less than five riders per bus at any one time (often only one or two riders) yet can control the lights and worsen traffic flow. Driver frustration is apparent, and it’s only a matter of time before a collision occurs.

WSDOT should revise its goals to focus on traffic congestion relief, which benefits all autos and road users, including transit, freight and emergency responders. The agency can look to other states that are leading in this effort. These changes are relatively inexpensive, and although invisible to the public (and thus not monumental for politicians), produce positive results.