Construction starts next month on major State Route 520 highway improvements on the Eastside, and an open house is planned March 23 from 5 to 7 p.m. at Chinook Middle School so commuters and neighbors can learn what to expect during the work.

The $306 million SR-520 Eastside Transit and HOV Project rebuilds the highway from Medina to Bellevue into a six-lane facility with two general-purpose lanes and a transit/HOV lane in each direction. Crews also will replace three overpasses with lids – two that will include improved transit facilities. Other work includes stream improvements to allow fish to pass beneath the highway and construction of bicycle and pedestrian paths.

When complete, the project is expected to improve travel times for buses and carpools and improve safety for 190,000 people in 115,000 vehicles who use the corridor daily. The six-lane project is scheduled to be open to traffic in December 2013. While construction is under way, drivers can expect lanes on SR 520 to remain open during weekday commutes. Lane and ramp closures will be scheduled during off-peak hours, at night and on weekends.

Staff from the project contractor, Eastside Corridor Constructors, and the Washington State Department of Transportation will be available to answer questions about project design, construction plans and potential traffic impacts. Staff will answer SR 520 tolling questions and sell Good To Go! tolling passes at the open house.

The latest construction and closure schedule is posted at WSDOT’s website.

The Eastside project is funded in part by future revenue from tolling that is scheduled to begin on the floating bridge this spring. The state Legislature set the SR 520 program budget at $4.65 billion for improvements from Interstate 5 in Seattle to SR 202 in Redmond. Toll revenue along with state and federal funds provide about $2.62 billion for the SR 520 improvements. WSDOT will continue working with lawmakers to identify additional funding to complete planned improvements in the corridor.