Commuters along State Route 520 are finding less congested traffic between Bellevue and Medina with the completion of new HOV lanes, wider shoulders and longer merging lanes at interchanges along a two-mile stretch of the highway.

A nearly three-and-a-half-year endeavor, the completion of the SR 520 Eastside Transit and HOV Project allows carpools of three or more people, vanpools, motorcycles and transit vehicles access to HOV lanes along some of the most heavily used parts of the highway.

With more than 70,000 vehicles driving across SR 520 each weekday, Andrew Richardson, spokesperson for the Washington State Department of Transportation, said the project was vital for creating a better flow of traffic, especially as Bellevue’s population continues to grow.

On and off ramps from SR 520 were also lengthened to make a more efficient corridor in both the eastbound and westbound sections of the highway, he said.

“Outside transit stops, especially at Evergreen, had a short merge, which created a huge bottleneck,” Richardson said. “Those have been moved to interior lanes and now the buses enter and exit the HOV lane on the inside, which will help traffic flow. We expect to see some real benefits to the busses and carpools.”

A joint venture between Granite and PCL Construction Services, the $336 million project also reconnected communities to the major highway that were cut off during its original construction in the 1960s, he said. Construction of a new roundabout at the 92nd Avenue Northeast interchange, an area that primarily serves Medina Clyde Hill, Yarrow Point and Hunts Point, now provides direct access to SR 520.

Crews also built stormwater treatment and detention improvements for fish passages, the first time in nearly 50 years.

Eight culverts that used to run under SR 520 and adjacent streets prevented fish migration to and from Lake Washington, Richardson said. Each has been replaced and now features passable structures for fish, including wider culverts that act as simulated stream beds with special rock and gravel allowing the fish to navigate underneath the highway for the first time.

Westbound

With the completion of the SR 520 Eastside Transit and HOV Project, crews and employees are now shifting their focus to the next step of the overhaul.

Expected to be completed in spring 2016, a new six-lane floating bridge will carry commuters across the water and meet up with the West Connection Bridge, which also finished construction this week. The structure will connect the existing four lanes in Seattle with the new floating bridge when it opens, according to WSDOT.

The following year, the West Approach Bridge North is slated to open, carrying three westbound lanes of traffic from the new floating bridge to Montlake. Once complete, the existing lanes in Seattle will be restriped in order to guide three eastbound lanes of traffic from Montlake along the West Connection Bridge meeting up with the new floating bridge.

Construction of the West Approach Bridge North Project is set to break ground later this month in Seattle. The bridge will also include a westbound HOV lane and an extension of the SR 520 regional, cross-lake bicycle-pedestrian path, Richardson said.