From WSDOT: 

The eastbound SR 520 closure scheduled for this coming weekend has been postponed. Due to weather and other factors, this closure will now take place in mid-November. Here are the details: 

• Where: Eastbound SR 520 between Montlake Boulevard in Seattle and 84th Avenue Northeast on the Eastside
• When: Between 11 p.m. Friday, Nov. 8, and 5 a.m. Monday, Nov. 11
• Why: Crews will shift traffic lanes, pave and restripe this portion of the eastbound roadway. Come Monday morning, Nov. 11, eastbound SR 520 traffic will be reduced to two lanes between Montlake and the floating bridge. 

This is how SR 520 will look for three to four years during construction of the Montlake Project.

View larger image (pdf 552 kb)

This traffic shift is necessary to allow crews to remove the existing eastbound lanes and rebuild them to modern seismic standards. The future eastbound bridge will carry traffic on two general-purpose lanes and one transit/HOV lane from Montlake to the floating bridge.