SEATTLE SUBWAY

Martin recently pointed out that having strong local constituents who care about transit is critically important to getting the most out of Sound Transit investments. We strongly agree. That is why we were encouraged by the Seattle Department of Transportation’s (SDOT) recommendations for the next Sound Transit ballot measure (ST3). The SDOT recommendations get a whole lot right: Emphasizing the necessity of multiple underground stops in the downtown core, identifying the need for expansion east of Ballard and recognizing the need to serve both the Denny Triangle and South Lake Union as best as possible with the line to Ballard.

In addition to all that SDOT got right, we think there two important further improvements:

SDOT identifies the likely best single line to serve the northern part of the Seattle core but this is an unnecessary constraint. SDOT’s suggestion leaves the second densest neighborhood in Washington State (Belltown) without a stop and serves South Lake Union (SLU) poorly. We should be looking to serve every dense core neighborhood with subway service.

It is possible to achieve this by branching the system at Belltown as shown on our map. This branching and transfer location has several advantages to the SDOT recommendation: Serves Belltown, Denny Triangle and SLU well while only adding a quarter mile of tunnel and one station.

A split service plan where West Seattle trains terminate in SLU and Ballard trains terminate south of the stadiums would add very frequent service through downtown Seattle where we know there will be a future capacity issue. It would allow different service frequencies to match potentially uneven north line/south line demand.

Transferring at Belltown will be a direct, center platform transfer and will take pressure off Westlake, which will be an even more crowded station in the future.

It may be possible to reuse the soon to be vacated Battery street tunnel for significant cost savings and easier construction. SDOT suggested further study of an at-grade option in addition to the publicly-preferred grade separated approach. The critical question here is performance. Grade separation improves the speed and reliability of not just the one line, but the entire system and grade separation’s advantages will be amplified as the system grows. We are not building a system for the next 10 years, we are building a system that will serve Seattle’s transit needs for a century or more. It’s important that studies consider the long-term constraints of the Interbay corridor that will be heavily used by freight, general purpose traffic, and alternative modes for generations. A system hobbled by unnecessary speed constraints, reliability issues caused by collisions at intersections, and inability to increase capacity due to limited headways does not meet our long-term needs as a city. As one of just two lines that crosses the Ship Canal, designing in unnecessary performance constraints will therefore risk losing the support of both advocates and voters.

Now is not the time to be considering compromises, particularly not for Seattle – the most critical transit market in the region. As we pointed out in our Sound Transit Complete article, the next Sound Transit package will be scaled to public demand. If we ask for more, it can be more. We look forward to working with Sound Transit, the Seattle Department of Transportation, and Seattle’s many pro-transit constituents to make sure that the next Sound Transit ballot measure is a plan that is very much worth voting for.