The Community Advisory Group working on the Columbia River crossing problem seems to be hellbent on making a wrong decision. All we ever hear about is a “replacement” bridge for the I-5 Bridge pair. A new “replacement” bridge somewhere near the existing pair would have all kinds of problems.
First, the purists will want a fixed bridge as opposed to a drawbridge, but such bridges are expensive and take up a great deal of space for on-ramps, service roads, and other infrastructure. A replacement drawbridge would give us a couple of extra lanes of traffic at best.
What’s wrong with keeping the existing bridge pair? They appear to be well-built, and have never failed in 100 years of operation. Clearly they’re insufficient to handle the traffic, so why not keep them and supplement them with something new?
A tunnel could be feasible. Tunnels have their own special problems and require an extensive geologic study, but they also have advantages. One is location. A bridge halfway between the I-5 and I-205 bridges would be impossible because Portland International Airport is in the way, but a tunnel terminating in that general area might work. Service roads and other infrastructure could be built between the two bridges without affecting the airport.