Seattle-Tacoma Traffic Among Most Unpredictable in Nation—How Does Your Commute Compare?

Heavy traffic is nothing new in the Puget Sound area, but a new study shows the severity of our rush-hour jams is especially tough to predict.

The latest Urban Mobility Report, released this week by the Texas A&M Transportation Institute, shows drivers in the Seattle metro area, which includes King, Pierce and Snohomish counties, spent an average of 48 hours—two whole days—sitting in traffic in 2011.

That figure ties Seattle-Tacoma with Philadelphia for ninth-place among the country's 15 largest metro areas when it comes to average hours lost to traffic congestion.

According to the Washington State Department of Transportation's 2012 Congestion Report, the stretch of State Route 167 between Renton and Auburn saw anywhere from 2 hours and 10 minutes (a.m. commute) to 3 hours (p.m. commute) of congestion in which average speeds were below 45 mph last year. The afternoon commute congestion, in particular, worsened notably since 2009 when the figure a mere one hour and 15 minutes. See pages 30-31 at http://wsdot.wa.gov/publications/fulltext/graynotebook/CR12.pdf for other major commute information.

The WSDOT report didn't provide information on routes closer to Sumner and Bonney Lake although the standard congestion begins as State Route 410 merges onto northbound SR 167 in the morning, and the afternoon commute slows considerably heading up SR 410 into Bonney Lake before the first stoplight at the Dairy Queen intersection.

Another aspect of the Texas A&M Transportation Institute study shows our region's traffic isn't just heavy—it's also highly unpredictable.

For the first time, researchers also measured the amount of a time a driver must plan to ensure on-time arrival 19 out of 20 times. Seattle-Tacoma's "Freeway Planning Time Index" came in at 3.99, meaning commuters must set aside 80 minutes to consistently arrive on time when traveling on a route that takes 20 minutes in light or no traffic.

The figure puts traffic in Seattle-Tacoma at 12th most-unreliable out of 101 urban areas across the country. Despite a significantly smaller population, nearby Portland actually scored higher than Seattle-Tacoma, with an index of 4.26.

Congestion in our region got slightly worse in 2011, according to the study, with the average number of hours lost in traffic increasing from 47 to 48. But these figures are markedly lower than 2006, when the average was 54 hours.

What congestion problem areas can you identify on your daily commute? How much time do you set aside each day to travel? Tell us in the comments section.