Current approaches to national road network planning generally focus on links and corridors in themselves and do not allow the assessment of each link as a component of the network as a whole. They do not provide any means to assess the quality of the network or the value of changes to it. This paper describes a study the aim of which was to demonstrate the effectiveness of accessibility based techniques for national network planning, and review the matter of devising accessibility based network performance measures which can help assess networks in terms of specific policies. Accessibility of one place to all other places is a function of the size and distribution of the other places and of the cost of getting to them. Accessibility can be shown to be a measure of the expected utility that people enjoy from the pattern of activities available to them, net of the transport costs, and changes in accessibility reflect changes in consumer surplus. The paper describes how the basic accessibility measure can be used to construct a wide variety of performance indicators that can be targeted to particular policy objectives. It then describes the national road network model constructed to test the techniques and shows the basic accessibility profiles developed using the model. Two performance indicator plots are given, one showing the degree to which the network approaches an idealised network, where every location is directly connected, and one showing the effectiveness of the network in serving a particular location. The network model is used to test and evaluate four hypothetical road projects. This model is used to assess and compare the overall benefit of each of these projects and the footprints of benefits, allowing the relative benefits received by each state as a result of these projects. (A)
Samenvatting