Construction of a new state Route 520 is kicking into high gear this week in the Montlake neighborhood and on Foster Island along the west shore of Lake Washington.
Contractor crews for the Washington State Department of Transportation (WSDOT) are beginning to move in heavy equipment and remove trees and vegetation, as needed, along a strip of Foster Island in preparation for building the West Approach Bridge North. One of the crews’ first tasks on the island and adjoining waterways is to build a work platform from which they will construct the permanent SR 520 approach bridge.
In a nearby staging area along the west edge of the Washington Park Arboretum, work is under way to place field trailers and other construction equipment.
Also, at the former site of the Museum of History & Industry, just north of SR 520, crews are preparing to demolish the building later this year. The demolition will make way for additional staging operations and, eventually, creation of a water-detention pond, where stormwater runoff from the highway will be naturally filtered and treated.
This month crews also expect to begin pile installation for the approximately one-mile-long work platform and will begin removal of the R.H. Thomson “ramps to nowhere” in the arboretum.
Crews will remove trees and vegetation within WSDOT’s right-of-way on Foster Island as needed to make room for the new West Approach Bridge North and work platform. Most of the trees being removed on the island are nonnative ashes and willows, which will be replaced with native conifers, shrubs and groundcovers.
More than 400 trees and 22,000 shrubs will be planted within the project area when construction is completed in mid-2017. Orange fencing will be placed near protected trees to ensure they are not damaged during construction.
The 1.2-mile-long, fixed-column West Approach Bridge North, mostly built on piers over water, will connect the new SR 520 floating bridge now under construction with the highway’s Montlake Boulevard interchange in Seattle.
When completed, the approach structure will carry three westbound lanes of traffic from the new floating bridge to Montlake. The new West Approach Bridge North, built to modern seismic codes, also will extend a new, cross-lake bicycle and pedestrian path from Montlake to Bellevue.