[pdxstreetcar]

How about elevated from SE 17th (where it could branch from PMLR) to 52nd where there is excess right of way from the Mt Hood Freeway land to run in a redesigned street in a median. Elevated stations at 21st, 39th. This is hardly an attractive highway anyway, so why not elevated?

On the other hand...

The place where you need exclusive lanes is where traffic is the worst, it makes little sense to build exclusive lanes where it is easy with excess capacity and little traffic. It actually improves traffic to take lanes at the most congested areas for exclusive use of HOVs, what viable alternative is a single bus carrying 100 people stuck behind a 100 people in a 100 cars? if you are going to sit in traffic no matter what, most people will choose to their own car. But that just makes traffic worse as it encourages SOV travel. At least prioritizing a HOV over SOVs gives people a real incentive to ride the HOV and therefore there is a real viable alternative.