Optimized Gravity Models for Commodity Transportation

This study is based on a comprehensive commodity flow survey done in Alberta in 1977, which covered the full range of commodity flows by different modes of transportation. The survey data is grouped into specific commodity categories and a set of O‐D tables has been developed. The O‐D tables are the basis for the development of gravity models for commodity flows. A set of gravity models, one for each commodity category, has been developed to represent the commodity flows on a province‐wide basis. The gravity model for each category has been calibrated by an optimization technique that uses a power function and regression analysis. The calibrated gravity model is termed the “optimized gravity model” to indicate the new technique of calibration. The developed models are acceptable as shown by statistical measures and commodity haul frequency diagrams.