A method to simplify network representation in transportation planning

Abstract The problem of Network Aggregation is defined as the simplification of the number of nodes and links in a transportation network. The objective of a network aggregation technique is to reproduce the level-of-service attributes (such as travel time) between any two points using a spider network as a proxy for the detailed. The aggregation procedure categorizes links into functional groups such as access, egress, line-haul, bypass and intra zonal circulation—which is a convenient classification in terms of transportation analysis. The technique presented here has several distinguishing advantages. First, certain invariance properties are maintained—for example the total trip miles of travel is the same whether measured in the aggregate or detailed networks. Second, the method is systematic, rather than judgemental, which means the inaccuracies introduced as a result of network aggregation can be measured in a scientific way.