Prioritize Stride BRT in realignment

Stride station rendering (image: Sound Transit)

With the Sound Transit 3 program realignment continuing to evolve and adjust to new revenue projections, Sound Transit is evolving its realignment scenarios. Now is the time to get serious about prioritizing projects. I believe that Sound Transit's Stride BRT lines are strong candidates for prioritization, and should be completed as soon as possible.

The main reason for this is that Sound Transit needs to provide a much smaller amount of infrastructure for BRT when compared to light rail projects. New BRT infrastructure mainly consists of the stations, modification to the roadway, bus bases, and buses. While still substantial, the cost of these components is much lower than the cost of constructing the guideway, track, and catenary required for a Link Light Rail line. An analogy to this is that it's like a light rail line where the track is already built for you, and you just need to build the stations. And the stations (with a notable exception) cost much less than light rail stations, since they don't need to accommodate long trains, and need much less platform space and vertical conveyance. While not quite as high-quality as light rail, Stride lines will run through areas where there is no prospect for light rail for the foreseeable future, and will make fast frequent connections to light rail. It will be an attractive option for people who aren't on Link, but could take Link in combination with Stride. Even some Link-only trips like Federal Way to Bellevue will be faster by switching from Link to Stride at Tukwila than switching Link lines at IDS, so the improvement to regional mobility goes well beyond the neighborhoods that are served by Stride.

On SR 522 and NE 145th Street, Stride S3 will fill in more BAT lanes to get more of the traffic out of the way of the bus, and full off-board payment will ensure that the bus only needs to wait long enough for people to walk off and walk on. The connection to Link at 145th reduces the amount of time riders have to wait in traffic, and expands the range of destinations that riders can reach quickly when compared to Sound Transit Express route 522 (which will be truncated to Roosevelt Station this year).

On I-405, the quality of the project will be a more significant upgrade. The north half will be significantly improved even since the representative project, with added direct access ramps and better integration with SR 522 Stride. The south side will be a dramatic improvement over the status quo. Current ST routes 560 and 566 have to deal with a busy and narrow I-405 freeway, with slow and insufficient HOV2 lanes. And that's when they can use them at all, since both freeway stations on route 560 are on right-hand exists (causing route 566 to skip them to save time). Did I mention the slow and insufficient HOV2 lanes? WSDOT is (as far as we know) planning on finishing the hard part of I-405 south Stride without years of delay. Without Stride, this will speed up route 566 (and, if restored, route 567), and do nothing for route 560. With Stride, 560 will go away and Stride will partially replace Kennydale service with a new freeway station at NE 44th that connects directly to the toll lanes. Route 566 will be moved into the slow lanes to provide peak service to the existing freeway stations. Stride will also speed up service to Burien with an inline station at TIBS replacing a deviation to the airport, and a stop in Renton that is problematic but still faster than today's route through Renton.

Cost comparison based on 2016 representative projects

Because so much of the infrastructure for I-405 Stride is being (or has already been) built by WSDOT, the result is a line that is much much cheaper than light rail. A good comparison is the Federal Way Link Extension. This short Link extension costs about $1 billion, and the result is 5.3 miles of Link light rail, and just two new light rail stations. I-405 Stride will cost about $850 based on the representative project, and adds 38 miles of BRT, with eleven stations! Granted, the cost of Stride has gone up due to additional improvements that Sound Transit is adding to the stations. But the cost of Federal Way Link Extension has also gone up, by $460 million for the entire Angle Lake to Federal Way line ($220 million extrapolated to the ST3 funded segment), or about 22% of the entire project. And that isn't even for improvements. That is all cost eaten by the complex and expensive infrastructure required for Link, and not BRT.

When cost-per-mile of both Stride corridors is compared to all other ST3 project corridors, the comparison is more dramatic. I-405 and SR 522 Stride easily make up two of the top three projects in terms of cost per mile, with the values being tiny in comparison to nearly every other project:

And not reflected in this graph are cost increases of other Link projects, most notably the West Seattle-Ballard Link Extension's cost increases totaling $4 billion, or 53% of the project's total cost. The story these numbers tell is clear: the best way for Sound Transit to deliver as much transit as possible within the bounds of its financial capability is to expedite Stride.

Sound Transit's latest realignment scenarios have been encouraging on this front, with I-405 Stride consistently being in the lowest delay category of two years (which would have I-405 Stride south opening in 2026, and north opening in 2027), and Sound Transit continuing to be open to deferring parking. But, disappointingly, SR 522 Stride tends to be in the five-year delay bucket, even with deferred parking, putting its likely opening date at 2030.