Abstract

This paper presents an analysis of the spatial and temporal interactions between truck flows across the Texas-Mexico border. The system of flows is modeled as a multivariate stochastic process with interactions both in time and space dimensions. A novel modeling approach, the space time autoregressive moving average (STARMA) model, is applied to capture the autocorrelations between the hows. These autocorrelations are the base to compute direct and crossed demand elasticities between the flows. The demand elasticities are used to estimate the degree of dependence between the truck flows both southbound and northbound, revealing that uneven adjustments take place in the truck flows pattern for southbound and northbound traffic. In fact, the southbound flows are more sensitive to changes in their own demand over time than the corresponding spatial changes. On the other hand, the northbound flows are more sensitive to changes in the demand for the main how (Laredo's bridge) rather than their own variations in previous periods. (C) 1999 Elsevier Science Ltd. All rights reserved.