One of the problems with building cities near waterways is this:  building bridges is just phenomenally expensive.  See, for example, the bridge across the Columbia River, connecting Portland, OR with Vancouver, WA.  It’s a rush-hour chokepoint, regularly clogged with drive-alone commuters; and transportation planners in both states are wondering what to do about it.  One option on the table is to build a shiny new bridge in basically the same spot—at a cost of a little over a billion dollars.  Another option is to spend just under a billion to build an entirely new bridge a mile to the west.

I have no special insight into whether either option makes any sense.  Perhaps so, if drivers are willing to kick in enough tolling revenue to pay for the exhorbitant construction costs.  Then again, increasing car capacity is bound to have all sorts of unexpected land use, fuel consumption, and public safety impacts that tolling, by itself, won’t account for—which could make either project a net loss for the region as a whole.

Either way, the Columbia River bridge is yet another stark reminder of the enormous financial burden that urban transportation infrastructure now carries with it.  When urban highways were first being built, back in the 1950s through 1970s, they were pretty cheap:  the land was relatively inexpensive, labor was cheaper, and lower design standards allowed for less costly construction. But now, as those early structures are nearing the end of their usable lives, we’re finding that they’re staggeringly expensive to rebuild: replacing a single highway or bridge can absorb a huge chunk of a metro area’s total economic output.  Seems like a pretty important lesson to have learned—but one that the region’s road-building agencies have yet to come to grips with.