Crunching the Numbers on Downtown’s Bus Capacity

ST Express 550 in Downtown Seattle Transit Tunnel / photo by SounderBruce on flickr

The One Center City bus restructure plan rolled out on January 26 contains some painful proposals, terminating ST Express 550 at International District / Chinatown Station, turning most of the West Seattle and Burien peak express routes (37, 55, 56, 57, 113, 116, 118, 119, 121, 122, and 123) into First Hill expresses, and having route 41 do a live-loop on Pike and Union. The plan also re-routes all SR 520 routes coming into downtown (252, 255, 257, 268, 311, and 545) to UW Station.

The cause of having to divert these routes is the seven bus routes (41, 74, 101, 102, 150, 255, 550) that will be kicked out of the Downtown Seattle Transit Tunnel in September of 2018 when Convention Place Station gets closed permanently for construction of the addition to the convention center.

There are several tactics to mitigate these 72 surfaced peak-hour runs without the pain of passengers from two major all-day routes and eleven peak express routes having to transfer at the edge of downtown.

• Go through with the SR 520 restructure as planned. Link can probably handle the additional passengers, in both directions, with the current fleet. This would remove 38 peak-hour trips from downtown (on routes 252, 255, 257, 268, 311, and 545), over half of what is needed to mitigate the end of tunnel joint operations.

• Enact the Rainier Beach Station / Southeast King County restructure that Aleksandra Culver described, but with the peak-express routes removed as Link's peak capacity allows for it. This would remove 22 peak-hour downtown bus trips collectively on routes 101, 102, 143, and 150.

• Truncate relatively-empty route 106 at Mt. Baker Station. Give it a frequency boost to align with the all-day Link schedule, as ought to have happened last fall. This would remove 8 hard-to-justify bus trips from downtown, at a time when road capacity is at such a premium that ST Express route 550 (which has 18 peak-hour trips) might get truncated at the edge of downtown.

• Truncate routes 158 and 159 at Kent Station. Truncate route 157 at Tukwila Sounder Station. Two more Sounder round trips are coming in September.

• Re-route route 74 to serve UW Station. This would get four more trips out of downtown, and make some former route 30 riders very happy.

If all these tactics were used, 77 peak-hour bus trips could be removed from downtown bus traffic.

Each truncation would be unpopular with some portion of riders on each route. But the OCC truncation plans (other than the SR 520 portion) appear to be much more painful.

Moreover, these truncations collectively only mitigate the surfacing of tunnel buses. There is still the matter of traffic impacts from construction of the convention center expansion, the new Colman Ferry Dock ($), the 1st Ave Streetcar, Madison Bus Rapid Transit, and that giant wormhole for a freeway under downtown. Determining these impacts is much more complicated than counting bus trips.