> The solution to this problem is utility tunnels. A tunnel network under road surface just for plumbing and cabling. Maintenance crews can just drive through in cars and do their jobs, without stopping traffic and digging out pipes. Many ultra-modern cities have one [empahsis mine].

That does not sound like a general solution to the problem, because it would be fantastically, unreasonably expensive to put one under every road. Seems like something that would only be reasonable in a 1) particularly expensive central business district of a 2) city being built from scratch.

IIRC, some of the biggest US cities don't have separate storm and sanitary sewers, because the cost of retrofitting an existing city would be prohibitively expensive. Installing utility tunnels everywhere would be even moreso.

You've got to be kidding. Utility tunnels are not even remotely a viable solution for Atlanta outside of maybe a few streets in the downtown area. The city (and wider metro area) is huge with thousands of miles of roads. They can't afford to dig utility tunnels.