Piecing together the road construction traffic puzzle

By Bart Treece

The name of the game is to keep traffic moving safely. But when there are several construction and maintenance projects that need to get on the road, the job gets complicated.

There really isn’t a “good” time to close part of entire stretches of highway in a large metropolitan area. However, the work needs to get done. Much of it is important for maintaining and preserving our aging infrastructure, like replacing bridge expansion joints (pdf 937 kb) on I-5 or patching the deck of the Ship Canal Bridge. Ignoring these issues would eventually mean unscheduled emergency closures that could impact your regular route to work. We all saw how badly traffic was snarled when a damaged joint needed repairs ASAP last week. This is why we try to schedule these closures when it affects the least amount of people, at night if possible. Some projects need more time, such as when there’s concrete involved which needs time to cure before its strong enough to hold the weight of hundreds of thousands of vehicles. That leaves the weekend, when fewer folks hit the roads.

White board showing Seattle events/closures
The white board where closures are initially
coordinated with large Seattle events and holidays

Looking at only weekends, we try to avoid four during the summer: Memorial Day, Fourth of July, Seafair and Labor Day weekend. This adds up to a whole month without weekend closures because we know those are big travel times. We’re now left trying to juggle projects on competing corridors, such as SR 520 and I-90 or SR 99, I-5 and I-405. It doesn’t take a traffic engineer to know that closing lanes in the same direction on north/south or east/west routes at the same time would be a very bad thing. Also add into the mix that there are several events including Mariners, Sounders, Husky and Seahawks football game traffic we try to take into consideration. We can’t forget weather, which isn’t always predictable in the ‘Pugetopolis’ region. The threat of liquid sunshine can push a weather-sensitive project back to another weekend.

With projects on every major route planned this summer, there’s not that many weekends left. When possible, we try to combine work to avoid spreading project impacts further along than needed.

This weekend, June 6 - 9

Region-wide traffic will be impacted by the work happening in Seattle this weekend. To keep people moving, we need your help by combining or postponing nonessential trips, carpooling or continue taking transit in order to avoid major backups.

Seattle area construction map

  • SR 520 - Both directions of State Route 520 will be closed between Montlake Boulevard and Interstate 405 from 11 p.m. Friday, June 6 to 5 a.m. Monday, June 9. During the closure, contractor crews will demolish an existing barrier on the west side of the floating bridge that will eventually tie into the West Connection Bridge now under construction.
  • I-5 - The two right lanes of northbound I-5 at South Spokane Street will be closed to replace aging bridge expansion joints from 10 p.m. Friday, June 6 until 5 a.m. Monday, June 9.
  • I-5 - A single lane of northbound I-5 near Interurban will be closed for guardrail repair from 6 a.m. until 2 p.m. Saturday, June 7.
  • I-5 - Saturday and Sunday, two northbound lanes across the I-5 Ship Canal Bridge will be closed daily from 3:30 to 11 a.m. for deck patching. 
  • SR 99 - Southbound State Route 99 from Denny Way to South Spokane Street will be closed from 10 p.m. Friday, June 6 until 5 a.m. Monday, June 9. During the closures, crews will shift southbound traffic onto a new alignment through the SR 99 tunnel project site. 

Traffic tools

Don’t let road construction detour your weekend plans. To help you navigate through the closures and congestion, check out the traffic tools that WSDOT offers.