Zach’s summary and analysis of the Tier 2 alternatives arising from Sound Transit and Seattle’s Ballard HCT study is excellent, and if you’ve not read it yet, you should do so. There are some good ideas and some less-good ideas among the options, and I’m sure by now, our regulars will have thoroughly digested them, but in this post I’d like to point out one option that I was hoping would have made it into the final analysis but didn’t, a variant of Corridor C.
First, I’d like to explain my criteria for a sensible downtown Seattle rail line, beyond the obvious ones of being frequent, direct, reliable and focused on areas of high ridership potential:
- It needs to be no worse than an existing express bus trip, including transfer time. Ballard’s express services are massively popular, but express service is expensive to operate, both in terms of operations (lots of deadheading) and capital (lots of buses that sit at the base twenty hours a day). Riders will revolt if we try to cut their service without offering them something at least as good. If we can cut the 15X, 17X, 18X and maybe the 28X in favor of better connecting services, that’s a shedload of buses we can reallocate to better all-day service at minimal cost.
- It needs to be grade-separated south of Denny. Lots of people worry about the top speed of transit service, but it’s not very important for in-city services (say, typical trips of less than ten miles, stops about every half-mile), because even a fully grade-separated train spends much of its time accelerating or decelerating for stations; frequency and reliability matter most. Assuming any of these lines will be both very frequent and reasonably reliable, the most important factor to minimize trip time is to avoid extended periods of very low speeds, e.g. slogging at-grade through the city center.
To the first point. The current scheduled time from 15th/Market to 3rd/Pine on the 15X is 19-21 minutes inbound in the AM peak. Supposing train headways of 10 minutes (i.e. a five-minute transfer penalty) and a couple of minutes of added walking, we need Market to Pine travel times below 15 minutes if we’re going to build a rail line worth getting out of bed for. Option C currently fails that test — but I think it could be fixed through much smarter design, at a plausible cost.
More after the jump. [Read more...]