Drive time map

Why the shape is not a circle

A drive-time area, or isochrone, stretches along highways and pinches where roads are slow, end at water, or climb mountains. From a town on an interstate, the 30 minute area often reaches much farther along the interstate than across country roads. Comparing it with a straight radius of the same center shows how much the road network matters.

How to use it

1. Click the map or search a place to set the start point.
2. Pick a time: 15, 30, 45, or 60 min. The default is 30.
3. Pick a mode: auto for driving, bicycle, or pedestrian. Changing either choice reruns the request for the same point.
4. The reachable area appears as a shaded shape. If the router does not answer, a notice explains that nothing was drawn, and you can try again or use the radius tool.

How the area is calculated

The tool sends your point, the minutes, and the travel mode to the isochrone endpoint of Valhalla, an open-source router, running on a public server hosted by FOSSGIS. Valhalla explores the road graph outward from your point, adding up travel time on each road, until the limit. It returns a polygon around everything reached.

Road speeds come from OpenStreetMap tags and Valhalla's defaults for each road type. There is no live traffic, so the car areas describe free-flowing roads. At rush hour real reach is smaller.

Car, bicycle, and walking

Each mode uses a different costing model. Bicycle routing prefers paths and quiet roads and avoids motorways. Pedestrian routing uses footways and sidewalks and walks at a steady pace. Switching modes reruns the request with the same center and time.

Walking and cycling areas depend heavily on how well paths are mapped locally. Where footpaths are missing from OpenStreetMap, the shape can look smaller than what you can really reach.

Good uses

Drive-time areas are the usual way to check a commute, compare where two homes let you reach in 30 minutes, or define a service area for a store. Once you have the shape, the population within a radius tool can give a rough idea of how many people live in a circle of similar size.

Reading the shape

Gaps inside the shaded area are places the router could not reach in time, often parks, water, or blocks with no mapped roads. Long fingers along a highway show where fast roads carry you. Compare two start points by running one, taking a screenshot, then running the other.