A new Alaskan Way corridor in Downtown Seattle will feature improvements for general-purpose traffic, transit, freight, and pedestrian and bicycle facilities. The project will also construct a pedestrian promenade, a continuous public open space that facilitates pedestrian movement to and along the waterfront located west of the roadway from S. Washington to Pine Street.

A combination of Class II Permeable LCC (open cell) and Class IV Conventional LCC (closed cell) was used as backfill for a retaining wall to extend Elliot Way. Preparation included excavation, shoring, and installation of ground anchors. With LCC, it is easy to pour around the ground anchors and maintain straight alignment of anchors. We placed open cell LCC first, serving as a majority of the backfill material that was directly underneath a sidewalk and cycle track. Water coming from an adjacent dirt embankment will be able to drain through the open cell LCC, mirroring the natural flow of water through soil. 2’ of closed cell LCC was required for placement underneath roadways because of its strength and ability to withstand the expected weight of traffic.