Excavators already have elaborate machines for making large holes through the earth, adaptable to many soil conditions. The machine cuts through rock and soil with a rotating head, and builds a cement tunnel as it goes, ultimately leaving a seamless tunnel. How about a modification to lay cables, which are needed for electricity, telecom (phone, Internet, or other data), or some other means?
Cable installers already have a technique for laying cable in low-accessibility areas in which a rope is tied to the cable, then the rope is pulled through the inaccessible area. The rope can withstand being tugged around more than a cable can, and once it's in place, it's tied to the cable on one end, pulled until the cable is in place, then untied.
So I'm thinking a microtunnel boring machine (with a radius of maybe 500 cm), which tows a rope behind it. When it reaches its destination, tie cables to one end, and yank it on the other. Voila, instant cabling. Cable in a tunnel often lasts longer than overhead, with less chance of being damaged by trees, helicopters, vandals, lightning strikes, or any of the other things that typically damage overhead cables. It's also more sightly. Locations with underground cable have an unobstructed view of the sky.
For best results, I recommend a copper electrical cable, an optical data cable, and a carbon-fiber support cable (to insulate and reenforce the strand) all woven together. This allows all cable-based services in a way that are least likely to interfere with each other.