Sequential models to determine intercity Commodity Transportation Demand

The objective of this study is to determine the demand for commodity transportation using the conventional sequential modelling approach. In this study, the amounts of productions and consumptions of commodities at various locations were obtained from a commodity flow survey (shipper and consignee type) conducted by Alberta Transportation, Edmonton, in 1977 and 1978. Optimized gravity model for distribution and Log-linear and Logit models for modal split were developed from the above survey data. These models are discussed in this paper. The above three stages of modelling process yield the demand for commodities between origins and destinations in the province of Alberta. Demands for commodities (flows) are represented graphically in the form of commodity flow diagrams (CFD) between the population centres (origins and destinations). They also show the demand for commodities between origins and destinations by different modes, truck and rail. The CFDs for a few selected centres are shown to indicate the pattern of commodity flows across the province. They indicate that truck transport dominates the movement of all commodities. The modelling procedures and the results shown in this paper are applicable for transportation planning.