Latest tunnel progress
June 15, 2018 update
Tunneling is complete and in March 2018 crews finished building the roadways inside the tunnel. In late spring 2018 installation wrapped up on the tunnel's 16 electrical rooms and the many systems that make the tunnel function.
What remains? Months of rigorous testing.
Seattle Tunnel Partners is now conducting multi-layered tests of the tunnel's operational and safety systems. Pre-functional tests ensure that each piece of individual equipment works (e.g. a sprinkler head). Functional tests check that the equipment works together as a system (e.g. the fire suppression system). Finally, integrated testing checks that multiple systems function together (e.g. the fire suppression system talks to the heat detection and the video cameras).
This video explains the complex safety systems inside the tunnel and how they work together to keep travelers safe.