In applied mathematics, the method of contraction hierarchies is a technique to simplify shortest-path routing by first creating precomputed "contracted" versions of the connection graph. It can be regarded as a special case of highway-node routing.[1]
Contraction hierarchies can be used to generate shortest-path routes much more efficiently than Dijkstra's algorithm or previous highway-node routing approaches, and are used in the OpenTripPlanner software.[2]