Isochrone map

An isochrone map (isochrone plan, isochrone diagram) in science and urban planning is a map showing areas related to isochrones between different points. An isochrone is defined as "a line drawn on a map connecting points at which something occurs or arrives at the same time". Such a map is sometimes termed simply an isochrone. In hydrology and transportation planning isochrone maps are commonly used to depict areas of equal travel time.

Source: [Wikipedia](http://en.wikipedia.org/wiki/Isochrone_map)