The Downtown Seattle Transit Tunnel (DSTT) and Link’s Stadium Station will be closed this Saturday, August 9th from approximately 5-11am. The closure will allow Metro and Sound Transit to test the joint U-Link and bus operations that will be in place from 2016-2019.
Link trains will terminate at SODO, and Shuttle Route 97 will operate from SODO to Westlake, serving all tunnel stops. Buses will operate their full routes, albeit on the surface. See Metro’s Alerts page for more details of each route’s surface routing.
U-Link will boost peak frequency from 8 trains per hour to 10 per hour, and those tunnel slots either have to be accommodated via improved operating efficiency or by surfacing buses. Metro obviously has every incentive to keep its buses in the tunnel, as the tunnel saves riders time and saves Metro money. Sound Transit, of course, has every incentive for U-Link to be as fast and reliable as true rapid transit should be. These incentives being at odds, tests like these try to find the operating level where Metro maximizes its bus throughput without damaging U-Link’s reliability.
Long term, of course, the tunnel is slated to be rail-only, but not until 2019. In the event that joint ops at 2016 service levels bring the tunnel to a standstill, some additional buses will need to be removed. For a prioritization framework about which routes are worth keeping in the tunnel, I wrote on the subject in 2012 when the RFA was ending, and I think the analysis still holds up fairly well.