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.
The cost of retrofitting an existing city aside, the sanitary sewer is a subgrade utility tunnel, by design and by cost footprint. If you're already digging a big ditch and installing infrastructure there, it doesn't cost much more to have space for other utilities. We're not talking about building a basement for the entire roadway, we're talking about dropping modest size pipes under the sidewalks (or in many places, the lack of sidewalks) and enabling access through manholes.
We are talking about a basement for the entire roadway if "[m]aintenance crews can just drive through in cars and do their jobs, without stopping traffic and digging out pipes," like the GGP was talking about. Also, that's what all the pictures in the previously linked https://en.wikipedia.org/wiki/Utility_tunnel look like.
> ...we're talking about dropping modest size pipes under the sidewalks (or in many places, the lack of sidewalks) and enabling access through manholes.
I think you have a different idea, which sounds like conduit or something between conduit and a full tunnel.