Traffic jams have plagued the Seattle area for weeks. Now a traffic data company reports that congestion has been getting worse even before the traffic snarls of the last few weeks.
INRIX of Kirkland says congestion was up 7 percent in 2013. Seattle drivers wasted 38 hours sitting in traffic, four more than they did the previous year.
The worst segment of traffic? INRIX says that I-5 from north of Northgate to Union Street in downtown Seattle now tops its list of worst routes in the region. The average speed on that stretch is 16 miles per hour during the afternoon rush, making it the sixth worst route in the nation.
This drive unseats I-405 through Bellevue, which was the worst of the worst until the state’s transportation department completed work that eased congestion there. Despite that work, that stretch of I-405 is second on the list of the most-congested.
INRIX says road work does create congestion while it is underway. The most high-profile of is the Alaskan Way Viaduct portion of Highway 99. The tunnel boring drill nicknamed Bertha has been stalled for months, prolonging what was already going to be a painful congestion problem.
Jim Bak, a director at INRIX, says other contributing factors are job growth and people moving to the Seattle area.
"It's a 'good news, bad news,'” Bak said. “When traffic is bad in Seattle, it means the economy is humming along really well. But it also means we're spending a lot more time trying to get around.”
Job growth is up 3 percent in the region. Congestion, however, has increased more than double that.
Mark Hallenbeck, director of the Washington State transportation Center, says that’s partly because the roads network is running beyond its capacity, so the roads often can't handle increases and changes in the traffic flow.
"Too many of our roadways are at the point of breaking or well beyond the point of breaking,” Hallenbeck said. “These little changes when you're at the cusp have really big impacts on traffic congestion."
Recent weeks have shown that surface streets can't handle the load when I-5 or Highway 99 has a problem. In late May, a broken expansion joint cover on I-5 caused a 10-mile backup that swamped escape routes. On June 11, Seattle police closed Highway 99 to investigate a car accident, causing mayhem on a Mariners game night.
And Hallenbeck says cars are traveling so close to one another during peak demand periods that even when a driver slows down to read a text message, it can lead to a cascade of braking that ultimately leads to a traffic jam.