There's more infrastructure under urban roads. Crews come in to fix some utility, shred a section of a lane, patch it poorly with dissimilar materials, and leave.
There's more infrastructure under urban roads. Crews come in to fix some utility, shred a section of a lane, patch it poorly with dissimilar materials, and leave.
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.
2) Don't retrofit. Rather, if you dig up a street you put in the tunnel while you're doing it. Eventually all the important roads end up with tunnels.