For the past 4 months the SR520 Replacement Bridge has been inching across the Montlake Interchange. This phase of the project removes all of the existing south lanes of the existing bridge, and replaces them with a new and wider footprint called the “West Approach Bridge South” (WABS), similar to what borders Laurelhurst on its north side (WABN). The new contractor, Graham, heeded LCC’s concerns for an environmentally safer demolition than occurred from the WABN, and is not using the “rubblizing” method which was their word for grinding up the old concrete structure that contained toxins, and dumping into open barges up to Kenmore. The new method uses 69-foot high Gantry cranes to stabilize the bridge while the old sections are cut into large chunks, and removed to a facility off site to demolish, away from people and local wildlife.
The other change in construction is the installation of a stable work-bridge so that the new section will be built without barges, which requires an extraordinary amount of piles to be driven into Union Bay. The construction noise has been intense for residents in South Laurelhurst. In addition, the installation of support columns for the new bridge requires the use of vibrating hammers. Neighbors may feel a vibrating phenomenon from 7 to 10 a.m. through the beginning of April, as well as more noise.
The dedicated pedestrian/bicycle landbridge crossing over the new SR520 bridge will be located to the east of vehicular traffic. Construction has already begun as the casings for its support columns are being set into place right now through the spring. This shared use path that will connect the south Arboretum to Montlake and the University’s facilities and the Light Rail Station Completion is expected in mid 2024.
Both construction projects will require numerous SR520 bridge closures. Neighbors can check here for details and dates on future closures.