Yesterday’s Sound Transit Board meeting included two staff presentations important to the future of Sound Transit 3. Most important was the first revision to the draft list of projects to study for potential inclusion in ST3. Less significantly, the staff also presented the results of a conceptual study that caused much activist angst when it started, but seems to have spawned relatively benign conclusions.

Based on input from the ST Board in previous meetings, there were three changes to the draft project list from May 7th: ST added Madison BRT and a Tacoma Link Extension to TCC. They also clarified an ST Express item to explicitly include capital improvements to the HOV system.

The next step is public outreach, beginning June 4th and continuing through July 8th, using internet resources and public meetings. The staff will present these comments to the board to make final additions and deletions to the project list on August 27th. The project study will improve estimates for everything on the project list, providing better information for the Board to (potentially) form a package in the middle of next year.

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State law requires ST to conduct a conceptual study to gauge the impact of various investment levels. The takeaway that ST executive Ric Ilgenfritz highlighted from the conceptual study is, anticlimactically, that the benefits of ST3 expansion are roughly proportional to the size of the revenue package. In his words, “the more you spend, the more you get.” Best case, the maximum system attracts 566,000 daily boardings, or about 200,000 boardings above the ST2 best case.

There’s really not much more to say about the results, depicted in the figure above, and I’m not sure how productive further digging is. But Mr. Ilgenfritz did clarify a few points in response to my questions. Keep in mind that the more spine/less spine variations at spending level 3 are somewhat haphazard; as a quick reminder,the additional corridors in 3a are Ballard/West Seattle. 3b is Ballard plus Totem Lake/Issaquah, 3c is Ballard/West Seattle with no downtown segment, and 3d is just Ballard/Downtown. Option 4 is Ballard/West Seattle plus I-405 BRT. Full scenarios are here.