Spatial Economic Model for Forecasting the Percentage Splits of External Trips on Highways Approaching Small Communities

The main difficulty in forecasting traffic volumes in small urban communities is identifying the amount and destination of the external traffic. Three methods exist for determining the percentage of external traffic destined for the study community (external–internal trips) or through the study community (external–external trips): a comprehensive origin–destination study, a cordon line origin–destination study, and the use of regression equations. This paper examines the possibility of the use of an alternative technique, based on a spatial economic model, to determine the traffic distribution. The project uses an economic model, which includes surrounding community factors, to determine the trip rates for three communities within Alabama and compares the results obtained from this model with the results given by a commonly accepted regression equation and a recently completed cordon line origin–destination study performed by using video surveillance. It is demonstrated that the economic model performs well for the case study cities, and this model is recommended for use in providing estimates that incorporate a community's economic relationship to neighboring towns for traffic forecasting.