Description
This component calculates isochrones showing areas reachable within specified travel times. It uses road networks and routing algorithms.
How Travel Time is Calculated
Travel times are not derived from average speed × air (straight-line) distance. Atlas calls a third-party isochrone API that traces an actual road and path network and expands outward from each input point along real streets until the chosen time budget is spent. The output polygon is the boundary of all reachable locations at that cutoff.
Atlas routes the request to one of two providers based on the requested travel time:
- Up to 60 minutes — the Mapbox Isochrone API.
- Over 60 minutes — the HERE Isolines API.
In both cases:
- The routing engine respects one-way streets, turn restrictions, and the segments allowed for the selected travel mode.
- Each road segment carries its own assumed speed based on road class, surface, and mode — there is no single global speed constant (except walking, which uses ~5 km/h).
- The Driving with traffic option pulls live and historical traffic data from the routing provider so segment speeds reflect typical congestion rather than free-flow limits.
- For non-point inputs (lines, polygons), the analysis routes from the center point of each feature.
Inputs
Data [Dataset]Travel times [Array]Travel mode [Selection]Dissolve [Boolean]
Outputs
Result dataset [Dataset]