answer:It depends a lot on how old the road is. Several answers manifest in Manhattan. In two parts of town (Financial District and Grennwich Village) the roads are over 200 years old, way before cars, and they tend to follow either the lay of the land or shortest distance from A to B or the wall built to keep the pigs out (Wall Street… how ironic, pigs on the inside now). Broadway follows the ridge line of the island. Canal street is along a low zone that was swampy before they built a canal for cross-island transport (subsequently filled in). Then there’s the modern stuff, the grid plan. The numbered streets and avenues on a systematic grid that ignores topology. On bigger scales you’ll see roads heading in/out of urban centers and ports and to/from the pass in the mountains. As far as inclines a road will tend to be laid out to even out the climb to the pass.