Northwest 2020 Airport/Transit Best Project: The Downtown Bellevue Tunnel
The Downtown Bellevue Tunnel
Bellevue, Wash. Best Project
The first project in the larger $3.7-billion East Link light rail extension for Sound Transit, the sequential excavation method was chosen to ease the impact on the city during construction and speed the project’s timeline, but the tunnel required significant design changes to account for soft ground next to Bellevue’s high-rise buildings. The changes came with delays, but the team made up for the two-month delay, all while mitigating excavation issues around aging storm lines and granting early access to the tunnel’s utility contractor to allow the critical path activity for the overall project to begin earlier. The project embraced new uses of macro-synthetic fiber initial shotcrete lining, spray-applied waterproofing and shotcrete for the final tunnel lining, resulting in time and cost savings.