> Obviously no bridges should be coming down, but there is a real problem here of how to build and maintain a modern city that is smaller than the older one that it replaces.

If an area's population shrinks such that it doesn't need / can't afford all of its bridges, why not prioritize the critical bridges for maintenance and close the others as they become unsafe. Why is this always posed as a dichotomy between letting bridges fail and funding maintenance for each and every bridge?