Abstract
This paper proposes an Urban Network Impedance Model (UNIM) to estimate highway impedances within urban areas without employing current network simulation procedures. Point-to-point travel time, distance, and cost are the principal out-punts of UNIM. Inputs to the model are geographic locations of the two points, the service characteristics of the highway network as specified by a function that characterizes the distribution of isotropic speed throughout the metropolitan area, and an assumption concerning an idealized geometric configuration of the highway network. A method for calibrating the speed is presented.