Drivers headed east on State Route 520 this week should expect overnight ramp closures on SR 520 in the Medina and Kirkland areas.

Crews are placing guardrail to create a safe work zone to build sign bridges along SR 520. Drivers should expect the following closures:

● Wednesday, Sept. 30: Crews will close the exit from eastbound SR 520 to Lake Washington Boulevard in the city of Kirkland from 9 p.m. to 5 a.m. the following morning. Detour signs will direct motorists to the Bellevue Way exit, then east on NE 24th Street, north on 112th Street to Northup Way and onto Lake Washington Boulevard.

● Thursday, Oct. 1: Crews will close the exit to 84th Avenue NE from 9 p.m. to 5 a.m. the following morning. Drivers can follow a signed detour from the Bellevue Way exit to NE 24th Street and back to 84th Avenue NE.

Crews are constructing sign bridges over SR 520 between I-5 and 130th Avenue NE. The overhead structures will support electronic signs that display variable speed limits, lane status and traffic alerts. The technology, known as active traffic management or Smarter Highways, is expected to improve traffic safety and help reduce congestion.

Beginning summer 2010, drivers will see these high-tech signs on SR 520 and northbound I-5 in Seattle. I-90 will have similar new signs between Seattle and Bellevue in spring 2011.