NORBERT OPPENHEIM is Professor of Transportation in the Civil Engineering Department of The City College of New York, and at the Graduate Center, both of the City University of New York (CUNY), as well as on the staff of the Institute for Transportation Systems of CUNY. He received his PhD in civil engineering from the University of California at Berkeley. Among his many publications is Applied Models in Urban and Regional Analysis. He serves on the editorial board of Transportation Research, B. His current research interests are in network analysis, spatial demand modeling, and decision suppo...