Pi Index and the Shape of Transportation Networks

Pi Index and the Shape of Transportation Networks

Source: Adapted from Kansky (1963), p. 23.

The Pi index is the ratio between the diameter (d; vertical axis) and length of the network (horizontal axis). A low Pi index is linked with a low level of network development (such as simple corridors) and a high value of Pi is linked with a more extensively developed network (a system of linked cities).

L(G)D(d)Pi
130 km75 km1.733
245 km75 km3.266