Developing an Auto Ownership Model for Edmonton

The City of Edmonton has an advanced form of aggregate, equilibrium model for transportation system planning and analysis. Auto ownership is a key input to the mode allocation component of this model ñ expressed as the average number of vehicles per person 16 or more years old in each of the model zones. This paper describes the development of an endogenous process for forecasting auto ownership, incorporating the influence of changes in travel conditions on the propensity to own autos, and thereby providing representation of an important positive feedback in the system. Observations of the numbers of autos owned by households across the entire Edmonton Region were used together with information on household characteristics and travel conditions at the zonal level from the model to develop a representation of relevant influences on auto ownership, including zonal income, household composition and mode-specific accessibilities. This representation was then incorporated within the larger model system and the entire system re-calibrated. The intention is that this paper will include presentation of the results of some example model runs demonstrating the changes in forecast outputs arising with this extension to the model system.