Both directions of State Route 520 across Lake Washington and northbound Interstate 405 through Bellevue, WA will close simultaneously during the weekend of July 13-14, according to the Washington State Department of Transportation (WSDOT). The closures are to enable crews to do “critical inspections, repairs and construction.”

On Friday, July 12, at 10 p.m., work crews will close all lanes of northbound I-405 from SE Eighth Street to SR 520, as well as the eastbound and westbound I-90 ramps to northbound I-405. The exit to SE Eighth Street in Bellevue will remains open, but drivers are warned to expect heavy congestion and long delays.

At 11 p.m. Friday, both directions of SR 520 and all connected ramps between Montlake Boulevard in Seattle and I-405 in Bellevue will also be closed. Just two sections of SR 520 will remain open to traffic: I-5 to Montlake Boulevard and areas east of I-405.

Although I-5 northbound through Seattle is also expected to be unusually congested during these closures, truck drivers may still prefer to take that route, if possible, rather than being detoured off I-405 northbound onto surface streets in Bellevue. I-90 drivers wanting to go north on I-405 will also be detoured through Bellevue--- to Bellevue Way and 148th Avenue SE.

All lanes of both highways are expected to reopen by 5 a.m. Monday, July 15.

WSDOT cautions motorists to plan for long delays on I-90 near the detour routes, on westbound SR 520 approaching I-405, and on northbound I-405, where all traffic will exit to SE Eighth Street, as well as on I-5 through downtown Seattle. Surface streets in and around Bellevue will experience extra congestion as well.

 “Combining closures helps us limit summer weekend impacts on drivers while still allowing us to complete major work,” said WSDOT traffic engineer, Mark Bandy. “Scheduling this type of work isn’t easy. It must be carefully coordinated with other regional construction projects and avoid weekends such as Seafair, the Bite of Seattle and Bellevue Arts Festival.”

On I-405, crews will replace the 50-year-old concrete panels in the two left lanes between SE Eighth and Main streets, the length of a dozen football fields. Later this summer they will replace panels in the two right lanes. On SR 520, bridge maintenance crews will inspect the floating bridge. The annual inspection, which includes testing, maintenance and repairs, must occur during calm weather.

“The weekend closure of SR 520 and northbound I-405 will significantly affect traffic across the Puget Sound region,” said Lorena Eng, WSDOT’s northwest regional administrator. “We realize that not everyone can completely change their commute. But for those who have a choice, options such as vanpooling, carpooling or other forms of transportation can help avoid heavy congestion.”

Nice advice, but not much help to truckers.