Thank you for publishing this piece!

One line you quoted in this article is key to finding "proof" that ST3 is proceeding on an incomplete foundation.

"No Modal Alternatives Analysis conducted, calling into question the choice of light rail to serve the West Seattle-Downtown Seattle corridor."

I looked and could not find -- from any source or by any government agency -- a formal side by side comparison of the performance of a light rail line providing mobility between a station on the Link north-south spine and the three stations in West Seattle, compared to an optimized bus line providing transit service in the same corridor, presumably a vastly improved version of King County RapidRide C, including right of way improvements for faster service and bypassing congestion.

This study referenced in the scoping of the West Seattle FEIS is the last time light rail and buses were discussed and compared for downtown Seattle to West Seattle this South King County high capacity transit corridor study: 
https://web.archive.org/web/20150317074929/http://www.soundtransit.org:80/Projects-and-Plans/High-Capacity-Transit-Corridor-Studies/High-Capacity-Transit-Studies-document-archive/South-King-County-HCT-Study

Parts 2 through 9 of this South King County Study are no longer available on the web, so far as I can tell.  I am filing a PDA request for these documents.

Only the Executive Summary of the South King County HCT study remains visible:
https://web.archive.org/web/20180223051842/https://www.soundtransit.org/sites/default/files/documents/pdf/projects/hct_2014/201409_skccorridorhctfinalreport_113_1.pdf

The Executive Summary does not describe a modal alternatives analysis for the four station West Seattle Link Extension project now being served up.

Attached (at this link) is another summary of this work.  Not possible to use what's in this document to compare the light rail now planned for West Seattle with a bus alternative.

If a real mode comparison document existed, it would provide a foundation for a deeper conversation on whether $7 billion dollars for just 2,000 new transit riders following years of environmentally destructive construction of a railway is worthwhile.  

There is an argument that this comparison should have been carried out in the NEPA environmental analysis context underway and beginning after the ST3 tax vote in 2016.  Clearly, building light rail causes more environmental damage than expanding electric bus service.  What was done to keep buses out of the EIS process looks like general hand waving to me, not focused analysis. The discussion in the following Sound Transit pre-EIS document is the visible work that is closest to a modal alternatives analysis, but is clearly tilted from the git-go toward selecting light rail:
https://www.soundtransit.org/sites/default/files/project-documents/west-seattle-ballard-link-summary-of-previous-plans-studies.pdf
 

The Smarter Transit organization further argues that modal alternatives analysis should be carried out for all the ST3 Link extensions, including Ballard light rail, the Federal Way to Tacoma Freighthouse Square Link completion, the high capacity service beyond Lynnwood, and so on.

Thanks for your continuing attention to effectiveness and efficiency in transit choices.

John

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John S. Niles
President, Global Telematics | globaltelematics.com | linkedin.com/in/globaltelematics/
Executive Research Director, CATES -- Center for Advanced Transportation and Energy Solutions
Research Associate, Mineta Transportation Institute, San José State University
Board Member, Ridesharing Institute
Regional Associate, Urban Robotics Foundation