> Assuming That The Road Network Is A Connected Graph This is a really interesting issue in routing problems. Given the start and end coordinates, the temptati

> Assuming That The Road Network Is A Connected Graph This is a really interesting issue in routing problems. Given the start and end coordinates, the temptation is to "snap" them to the closest edge of the road network. Of course, when presented with real world data, one or both coordinates might unintentionally be close to a road that's part of a closed circuit (think race track or airport runway), or within a weight-limited set of roads that the vehicle cannot access etc... . So before running any kind of search algorithm, you have to have a pre-processing step that figures out the transitable component of the road network for that vehicle, and snap the coordinates to the closest edge on that component.