Someone much smarter than me once explained that TriMet sees itself as more of an urban development organization than a public transit agency, and their capital projects fetish is a big part of this. 

Also, I've studied the past two TriMet budgets and there's definitely some shifty stuff going on to obfuscate massive amounts of debt servicing and dubious capital planning work.

The SW corridor needs a traffic solution, but it doesn't need to be a billion dollar boondoggle.