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 km | 75 km | 1.733 |
| 245 km | 75 km | 3.266 |