ST3 Level 1 Alternatives: West Seattle

On its way to producing a single "preferred alternative" in early 2019, Sound Transit is in a year-plus process of collecting public input and screening a number of variants on the Seattle "representative alignment" voters saw before the 2016 vote. These "Level 1" alternatives are getting some basic, qualitative analysis across a wide series of metrics (below). The Stakeholder Advisory Group is reviewing these alternatives and will make its recommendations on April 24th. An Elected Leadership Group will consider this and make its own recommendations, and in May the Sound Transit Board will move a subset of these alternatives forward for further technical analysis and public comment.
In West Seattle, the representative alignment is elevated tracks from Sodo to the Alaska Junction, with two stops at Delridge and Avalon. These three stations intersect the three main north/south corridors in West Seattle, each with frequent transit service.

Public comment and further analysis spawned five alternatives. If you stare at it a while, the map below actually makes them pretty clear:

click to enlarge

It's self-evident how these alignments try to address different concerns, like:

• moving away from activities at the port;
• moving track away from certain neighborhoods
• burying the track near Alaska Junction
• orienting the terminus North/South to ease a future extension to White Center

Notably, all of these alternatives increase the cost except the light blue line that eliminates Avalon to tunnel to the Junction. As one might imagine, this also serves fewer riders and moves the stations further away from relevant activity centers. Briefly:

1. The Pigeon Ridge/West Seattle Tunnel alignment (purple) is easier to extend and has fewer curves to slow down trains. But two tunnels, and a water crossing at a potential superfund site, adds lots of risk.
2. The West Seattle Bridge/Fauntleroy alignment (dark blue) also points south, but the Junction station is a few blocks too far east, Delridge is in the middle of nowhere (and not well integrated with buses), and it might mess with port operations. It does avoid some environmentally sensitive areas.
3. The Yancy Street/West Seattle Tunnel alignment (pink) basically just adds a (long) tunnel to the dark blue line with a consolidated station by the Nucor plant. This is expensive, low-ridership, and messes with the port, but will appeal to people who want light rail to have as little "impact" on West Seattle (in every sense) as possible.
4. The Oregon Street/Alaska Junction alignment (gold) is the smallest change, but improves bus integration and worsens port impacts while pointing the line south.
5. The West Seattle Golf Course/Alaska Junction alignment (light blue) tunnels into the Junction and straight-up eliminates Avalon Station. By going over the golf course, it keeps tracks away from houses but also triggers a Section 4(f) review, where FTA has to certify that there is no significant impact to recreational areas.

I suspect that most STB readers will care very much about long-term transit outcomes, and may have mixed feelings about whether elevated track is such an eyesore or not. From this perspective, it's pretty straightforward to conclude that Oregon Street/Alaska Junction (gold) or Pigeon Ridge/West Seattle Tunnel (purple) provide the most useful train for future residents. The purple line has fewer turns and the best placement of Delridge Station*, but with a substantial increase in project risk. The summary slide (below) also hints that the purple line is way more expensive, requiring "3rd party funding". The Yellow line moves Alaska Junction to the West, increasing the line's walkshed. Without numbers, and an understanding of what other important projects might trade off here, it's hard to make a final judgment between the two.

* by being further South, the purple Delridge station is closer to more people and keeps buses out of the mess around the West Seattle bridge.