New York City is used in this example, but the same applies everywhere. The key paragraph:
“Infrastructure is a lot more complicated than the last time we did this on a grand scale. It’s not a matter of laying down new roads and tracks, as it often was as recently as the 1950s with the creation of the Interstate Highway System. In urban or crowded suburban areas where service can’t be shut down and new assets can get in the way of old ones, construction and repair is like performing open-heart surgery on someone while he’s playing tennis, as the planners of Boston’s Big Dig — now finished and serving Boston well — used to say.”
But read the whole thing.