SR520 Bicycle and Pedestrian Path Opens Today

The 520 bike and pedestrian path under construction. Credit: Lizz Giordano

Over a year and a half after the new State Road 520 bridge opened to car traffic, pedestrians and cyclists will finally be able to cross Lake Washington using the floating bridge. The new 2.7-mile 520 bridge shared-use path, linking Seattle and the Eastside, is set to open at 3pm on December 20.

Not only will this expand commute options, the new SR 520 path will also add to the 60-mile Lake Washington Loop Trail. Cascade Bicycle Club is planning several inaugural rides starting on both sides of the bridge to celebrate the grand opening.

On Cascade's blog, Vicky Clarke, a policy manager for the group wrote that "For the region, the bridge trail represents a step toward our future: transportation infrastructure that's accessible to all, and the ability to get more places by bike."

An "out and back" version of the trail, which extended from Medina about 1.3 miles across the bridge leaving Seattle just out of reach, has teased bike commuters and pedestrians since it opened in summer 2016.

On the Seattle side, the complete trail set to open Wednesday starts at Montlake Park near the Arboretum and runs along the north side of the rebuilt bridge, ending in Medina.

WSDOT's specialized sweeper Broom Hilda. Credit: WSDOT

A concrete barrier separates the 14-foot wide multi-use path which has 11 viewpoints and resting areas dotting the trail. WSDOT said a specially designed railing will provide views of the lake while keeping non-motorized travelers safe. The path has a 15 mph speed limit and bicyclists and pedestrians are not required to pay the toll. A specialized sweeper, nicknamed Broom Hilda, will be used to keep the shared-use path clean.

Eventually, the path will extend to Interstate 5, passing under Montlake Boulevard and 24th Avenue, then crossing over SR520 to the south side of the highway, and there connecting into the bike network, including the Burke-Gilman Trail and the Washington Park Arboretum Waterfront Trail. Work will continue in that area as crews build a freeway lid and interchange around Montlake.

Now that the bridge accommodates both vehicles and non-motorized traffic, could light rail be next? According to WSDOT, the new floating bridge is "engineered to accommodate light rail in the future." The bridge was designed in a way that additional supplemental pontoons could be added to support the weight of light rail. A white paper on the subject was released in 2010.

Credit: WSDOT

The agency said adding light rail could be done by converting the bridge's existing HOV lanes to light rail or adding width to the bridge to make room for light rail in both directions. WSDOT estimates either option would come at a hefty price, costing at least $150- $200m to add the additional 30 pontoons needed to support the weight of the trains.