The Transport System

The transport system can be conceptualized as the set of relationships between nodes, networks and demand. Demand for the movement of people, freight and information is a derived function of a variety of socioeconomic activities. Nodes are the locations where movements are originating, ending and being transferred. The concept of nodes varies according to the geographical scale being considered ranging from local to global (poles of the global economy). Networks are composed of a set of linkages derived from transport infrastructures. The three core relationships and the impedance (friction) they are subject to are:

• Locations. The level of spatial accumulation of socioeconomic activities jointly defines demand and where this demand is taking place. Impedance is mostly a function of the accessibility of nodes to the demand they service.
• Flows. The amount of traffic over the network, which is jointly a function of the demand and the capacity of the linkages to support them. Flows are mainly subject to the friction of distance with distance being the most significant impedance factor.
• Terminals. The facilities enabling access to the network as terminals are jointly characterized by their centrality and the linkages that radiate from them. The capacity of transport terminals to handle flows is the main impedance factor.