The Problem of Congestion Unreliability Cost: The Certain Error of a Mean and the Measure of Travel Time Utility Gains from Public Works

Abstract

This summary-for-students presents the claim of some recent analyses of home-based daily urban trips made in France or in the USA that the first four moments of travel time, not just the first, matter and that travelers react to changed service on road or transit networks by adjusting all four of their constructed trip duration moments, including the three higher moments characterizing time unreliability. Sole reliance on mean time changes to evaluate improved or worsened trip conditions then short-changes the benefit-cost analysis and notably fails to explain fast fill-ups and super-peaks that are part of the demanded trip time profile.