a bicycle path...above ground cold water line...doesn't sound all that complicated unless you left out some critical details....I'll make some assumptions...
Assuming bike path is non-motorized vehicles and is narrow and paved (or unpaved, doesn't matter), open cut the path and lay your coated steel or plastic pipe using 45 degree fittings. I will assume you don't need to go very deep with the line at this location...say about 3 feet from the crown of the bike path to the top of the water pipe. Cover the pipe with sand or smooth soil and cover and compact. Make the entry and exit locations in wide clearance of the bike path at least to the limits of the bike path easement. Recover the path to acceptable surface and you're done. If the path is in public property like a park or adjacent to a motorized roadway, you will need to check with the authority responsible for the maintenance of the path to get permitted for the crossing. I am assuming you have the right-of-way and easement to lay the line across the path.
You didn't mention much about having to protect the "cold" water line from freezing or maybe "sweating" in a humid climate. If you do, insulate. If you don't, don't worry about it.
Good luck.
Bob Lyons (OrangedDog70)