Fast travel-distance estimation using overhead graph

Shortest path can be computed in real-time for single navigational instructions. However, complex optimisation tasks, lots of travel-distances (lengths shortest paths) are needed and the total workload becomes a burden. We present fast method estimating travel-distance from one location to another by using an overhead graph that stores ratio between bird-distance few representative locations. The is then estimated any two locations corresponding value their nearest nodes graph. test within optimization setting where goal relocate health services so patients minimised. build road network information Open Street Map experiment with real-world data region North Karelia, Finland as part ongoing IMPRO project. results show average estimation error 0.5 km 512 nodes, processing time reduces 1.2 hours 2.9 seconds per iteration process. 2%, on average, which significantly smaller than 8% second best method.