Probing a die-hard traffic congestion controversy, this paper scrutinizes two key variables, density and flow, under equilibrium versus optimal states.

The authors explore the properties of various types of public and private pricing on a congested road network with heterogenous users allowing for elastic demand. Heterogeneity is reprensented by a continuum of values of time. The network consists of both serial and parallel links, which allows...

Some road-pricing demonstrations use an approach called "value-pricing", in which travelers can choose between a free but congested roadway. Recent research has uncovered a potentially serious problem for such demonstrations: in certain models, second-best tolls are far lower than those...

The standard economic model for analyzing tarffic congestion, due to A.A. Walters, incorporates a relationship between speed and traffic flow. Empirical measurements indicate a region, known as hypercongestion, in which speed increase with flow. We argue that this relationship is unsuitable as a...

We present a simulation model designed to determine the impact on congestion of policies for dealing with non-recurrent congestion (i.e. travel time uncertainty).

This chapter describes how transportation demand is analyzed and what has been learned from doing so. We first present a selection of the most important transportation demand models, with an emphasis on disaggregate models because they have generally been the most successful in capturing...

Urban transportation involves imprtant nonlinearities in two ways: in its purpose and in its form of provision. Under such conditions, there is ample room for market failures and it is not surpising that public intervention plays a heavy role. But public policy failures are common too, and many...