ST3 Level 3 Alternatives
Sound Transit's latest batch of options for Ballard and West Seattle kills off many variants, but controversies remain. The options are grouped into three concepts, although ST is free to choose bits from each alternative. All we have is maps, but that won't stop us from having a detailed look.
Representative alignment
The "representative alignment," which voters approved in 2016, remains in play. It's a pretty good alignment if you don't mind elevated track, with stations on both ends in the sky. There are nits to pick. Alaska Junction station points west, which doesn't help a future extension to Burien. Delridge is a bit far north, putting more industrial land in the walkshed and lengthening the bus ride for most people. Midtown is under 5th rather than 6th, reducing the combined system walkshed. The new Westlake is under 6th, worsening the transfer with the existing one.
On the other hand, this is within the budget. Alaska Junction is just to the East of California, where the new density is going in. Smith Cove and Interbay have locations that are about as promising as they could be (not very). 15th is a good spot for Ballard Station.
The "elevated" option is a tweak of the representative alignment to fix some of the most glaring errors. Alaska Junction turns south. The downtown tunnel runs under 6th Ave and Mercer St. By (expensively) extending the north end of the tunnel and using the BNSF right-of-way, the Ballard line almost entirely avoids 15th Ave. Regrettably, Smith Cove and Interbay stations are in the middle of nowhere, and the line finds its way to 14th Ave in Ballard, which is a bad place to end up. I guess cruise ship passengers will like it.
The "tunnel" option presumably blows the budget, and still has a lot of problems. They couldn't settle on a Alaska Junction location, including one that overshoots the density to the wrong side of California, bordering the sprawl. Delridge Station is a bit off Delridge, making those critical transfers worse. South Lake Union is far enough south (at Harrison) that it arguably doesn't serve a lot of South Lake Union. Smith Cove is in decent spot, but Interbay still isn't. They also couldn't resolve a 14th or 15th Ave site for Ballard station.
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What's the best for future riders while remaining within budget? The elevated option fixes the problems in West Seattle. It's hard to get too excited about one block shifts in downtown Seattle proper, so ST should do whatever is cheap and put the money into good transfers at Chinatown and Westlake. In South Lake Union and points north, all this process has come up with worse alternatives than the representative alignment. Rather than pointlessly extending the downtown tunnel or marooning riders in a railyard, ST should just run down 15th and actually serve people. (As long it's high enough to not be a frequently opening drawbridge).
It would be foolish to increase financial and project risk to bury the line at either end. However, if those neighborhoods have the leverage (and the supplemental funding sources) to tunnel, Alaska Junction should be below 41st or 42nd avenues. The Ballard Line should stay on 15th, whether above or below ground.