Why doesn't Google just run Dijkstra faster?
Dijkstra explores radially from the origin, expanding into every nearby neighbourhood before reaching the destination. Speeding up individual steps doesn't help—it still touches millions of irrelevant nodes. Contraction Hierarchies works by structurally skipping them, not computing faster.
Answered in
Why Google Maps Computes Shortcuts OfflineContraction Hierarchies precomputes shortcut edges offline so routing queries skip neighbourhood streets and touch only 2,000 nodes in under 10 milliseconds.
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