You often do, if the street has been there for a while. The exact location of underground infrastructure was rarely documented in the past. While the city should have a general idea of what lies under the street, you usually have to dig the street up to determine where you can install new infrastructure safely.

OK, you are clearly not a construction professional but you are confidently wrong so you must be a programmer.

Yes, telecom companies will lay new backbone fiber during a total road reconstruction because someone else is ripping up the pavement. Gas companies do the same thing along with water utilities. Streets where I live are completely redone every 60 years, it’s mill and overlay between those total reconstructions which does not allow access to the subsurface.

When this is not happening and fiber installs need to happen, they dig two pits and directional bore.

I see fiber companies directional boring everywhere on the suburbs to build out their network without ripping up entire roads.

> exact location of underground infrastructure was rarely documented in the past. While the city should have a general idea of what lies under the street, you usually have to dig the street up to determine where you can install new infrastructure safely.

Fiber does not run under the street in most residential areas, it’s laid in the utility ROW near the edge of the road/sidewalk so a handhole can be installed on the customer’s property to run a service drop to their demarc. I’ve seen fiber laid for residential networks in multiple jurisdictions in my area and that’s how it’s done.

Well, that's "small" digging, but you still need maps and permissions.