I needed to run a hose under a 3' sidewalk as part of my drip irrigation system and saw this on youtube. As I started, 2 neighbors came over to see what I was doing and ended up helping. The sidewalk was new and we were blasting through a combination of gravel, sand and a few bigger rocks.  It took the 3 of us about 20 minutes. Would have been faster if I'd followed the directions and dug the entry and exit channels a big longer.  Also, we ran into a big rock and had to shift a few inches. Once we hit just sand, it was smooth going.