Improved Contraction Hierarchy Queries via Perfect Stalling

Abstract

Contraction Hierarchies (CH) are one of the most relevant techniques for accelerating shortest path-queries on road networks in practice. We reconsider the CH query routine and devise an additional preprocessing step which gathers auxiliary information such that CH queries can be answered even faster than before. Compared to the standard CH query, response times decrease by more than 70%; compared to a well-known refined CH query routine with so-called stall-on-demand, response times still decrease by more than 33% on average. While faster speed-up schemes like hub labels incur a serious space overhead, our precomputed auxiliary information takes less space than the graph representation itself.