Methoden vergleichen

	Isochrone Analysis	Accessibility Analysis
Fachgebiet	Human Geography	Human Geography
Familie	Process / pipeline	Process / pipeline
Entstehungsjahr	1959	1959
Urheber	Edsger W. Dijkstra (shortest-path foundation)	Walter G. Hansen
Typ	Computation of travel-time contours reachable from a location on a network	Spatial index of the ease of reaching opportunities from a location
Wegweisende Quelle	Dijkstra, E. W. (1959). A note on two problems in connexion with graphs. Numerische Mathematik, 1(1), 269–271.	Hansen, W. G. (1959). How accessibility shapes land use. Journal of the American Institute of Planners, 25(2), 73–76.
Aliasnamen	Travel-Time Analysis, Isochrone Mapping, Service Area Analysis, Travel-Time Contours	Hansen Accessibility, Gravity Accessibility Measure, Potential Accessibility, Spatial Accessibility Index
Verwandt	4	4
Zusammenfassung	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.	Accessibility analysis measures how easily opportunities — jobs, shops, clinics, parks — can be reached from a given location, combining the attractiveness (size) of destinations with the cost of travelling to them. The gravity-based formulation introduced by Walter Hansen in 1959 sums the opportunities at all destinations, each discounted by a distance-decay function of travel cost, producing a single accessibility score per origin that has become a foundational concept in transport geography and urban planning.