OK, so I've got another proposal for the Columbia River Crossing:
A regional commuter rail network, based initially on DMU technology. The relevant two links would be Vancouver to Washington County, and Vancouver to Downtown Portland.
This would not replace light rail, but rather supplement it.
Gee, I must be a DMU fan, this is the second time in as many weeks that I've brought up the topic.
The Vancouver to Washington County connection would utilize abandoned rail ROW that runs from near the west end of the St. Johns Bridge to the Beaverton/Hillsboro area, and would require extension track, bed and trestle reconstruction. I bet that DMU passenger service between Washington County and Clark County could be initiated for a fraction of the cost of a new freeway, and if everybody is right about the volume of traffic between those two points, it would do quite well.
Of course, there is the matter of the spectacular railroad trestle that burned to the ground about a decade ago, which would need to be re-built along with much of the rest of this line (if, in fact, any of the rails/trestles/tunnels are still serviceable). However, the fact that the ROW exists already should still bring the cost of implementing a new service in this corridor way down.
Perhaps DMU service could be implemented before light rail service; in this scenario, the Portland to Vancouver run might ultimately be replaced by light rail into downtown Vancouver... or it might remain as a more expensive (fare-wise) express service.
It would be interesting to determine if a stop near St. Johns might be possible for both of these services, as the only interim stop between Portland and Vancouver.
Longer-term, this basic network could add routes to Columbia County (St. Helens & Scapoose), to McMinnville, and out the Gorge to Hood River & The Dalles.
The era of building freeways in Oregon is over. We now need to think of better ways to get people around, for less money and less damage to the natural landscape. Putting old railways back to use to serve new markets is an example of the type of innovative thinking that will cause Oregon to emerge as a leader in the 21st century.