3.5.1 Regional variations in network geometry Study of the particular structure of regional networks has been greatly helped by the development of a set of measures based on graph theory. These measures are described at length in Section 9.7, and readers are referred to that section for formal definitions of terms used in the following discussion. Two illustrations of Kansky's (1963) findings are given in Figure 3.19 where the railway networks of selected countries are related to their general level of economic development. In the first graph (Figure 3.19A), energy consumption