Transportation and Traffic Theory Research
Selected papers from the 19th International Symposium on Transportation and Traffic Theory held in Berkeley, California (July 18-20, 2011) this year are now available in volume 17 of Procedia: Social and Behavorial Sciences.
Though automobile traffic theory has remained a focus of this series, its scope has expanded over the years to include theoretical contributions on a variety of transport topics. The symposium’s uniqueness perhaps lies less in its subject matter than in its rigorous scientific approach in exploring and advancing these topics.
This year’s selections include “A maximum entropy-least squares estimator for elastic origin-destination trip matrix estimation” by CTR researchers Chi Xie, Kara Kockelman, and Travis Waller:
This paper discusses an elastic O-D flow table estimation problem for subnetwork analysis. The underlying assumption is that each cell of the subnetwork O-D flow table contains an elastic demand function rather than a fixed demand rate and the demand function can capture all traffic diversion effect under various network changes. We propose a combined maximum entropy-least squares (ME-LS) estimator, by which O-D flows are distributed over the subnetwork so as to maximize the trip distribution entropy, while demand function parameters are estimated for achieving the least sum of squared estimation errors.