Supernetworks for Combined Travel Choice Models

A supernetwork is usually defined as an augmented network that consists of a “basic network” for route choice and a “virtual network” for other travel choices. Supernetwork representations are useful pedagogical device to interpret various combined travel choice models as an extension of the fixed demand traffic assignment problem. Based on three proposed criteria, this paper reviews current supernetworks and modifies them as needed for better representation. A nested combined model consisting of four choices subject to variable demand is described with an example. Using supernetwork representations, combined travel choice models have great potential to become more popular than sequential four-step travel demand forecasting, even with feedback. In addition, recently developed quick-precision traffic assignment algorithms could be more efficient than traditional multistage solution algorithms for solving combined travel choice models. The proposed new supernetwork representations can be extended to other network problems in the supply chain network or other economics networks with minor modifications.