A NOTE ON THE TRAVEL SPEEDS DEBATE

This note challenges the use of census data for evaluating changes in commuting speeds, partly because these data require indirect distance measures, but primarily because they do not differentiate between non- stop trips and trip chains. The proportion of trip chains to total tri ps increased between 1983 and 1990 (Nationwide Personal Transportation Survey). Hence, results of declining speeds based on census data may be spurious. When trips are broken down by type using Nationwide Perso nal Transportation Survey data, speeds increased between 1983 and 1990 for all categories, in all but one of eight cases studied, by signifi cant amounts. (C) 1997 Elsevier Science Ltd.