Isochrone Analysis

Isochrone analysis computes the area reachable from a location within a given travel time, drawing contour lines — isochrones — that enclose everywhere you can get to in, say, 15, 30, or 45 minutes. It rests on the single-source shortest-path problem solved by Dijkstra's 1959 algorithm: from an origin, the travel time to every node of a routable network is found, thresholded, and converted into a polygon of reachable space. Isochrones turn an abstract travel-time field into an intuitive map of reach, and underpin service-area planning, accessibility measurement, and location analysis.