Transpn Res. Vol. 3. pp. i-xii. Pergamon Press 1969. Printed in Great Britain

TRANSPORTATION RESEARCH VOL. 3 No. I

ENGLISH, GERMAN, FRENCH AND RUSSIAN ABSTRACTS

OF THE PAPERS APPEARING IN THIS ISSUE

J. F. PIERCE: Direct search algorithms for truck dispatching problems-Part I. Transpn Res. 3, l-42.

Problem-solving procedures based on the methods of combinatorial programming are considered for solving a number of truck dispatching problems. Attention is focused on single-route problems such as typified by the problem in which a single truck operates from a central depot to deliver items to a number of geographically dispersed destinations. Characteristics of problems considered include deadline and earliest delivery time constraints on the acceptable delivery time at specific destinations, optional deliveries, split deliveries and constraints on the carrier such as volume limit, maximum number of stops per trip and maximum time per trip. All of the problem-solving procedures are reliable in the respect that when carried out to completion they guarantee the discovery of an optimal solution when one exists.

M. C. GOOD, K. J. ROLLS and P. N. JOUBERT: Driver-vehicle behaviour in free-path turns. Transpn Res. 3, 43-68.

Tests were performed in which six drivers were instructed to make comfortable turns through various deviation angles at different forward speeds, constrained only by the final heading and the imposed condition of longitudinal acceleration. It was found that the lateral accelerations and jerks utilized by the drivers were higher than would be used in normal driving, and increased with both vehicle speed and deviation angle. Although drivers rated turns with high lateral acceleration as uncomfortable, this quantity seemed to have little effect on the vehicle path selected by drivers. The maximum yaw rate and yaw acceleration, however, were generally independent of forward speed for a given deviation angle, except when the lateral accelerations were very high. Yaw rate increased approxi- mately linearly with the logarithm of deviation angle for angles between 30” and 240”. These results have implications for the design of freeway loops and ramps and for the provision of visual information for the detection of yaw rate.

A. W. SCHOENNAUER: Airline schedules and their impact upon passenger trafic. Transpn Res. 3, 63-73.

This article reports the findings of an analysis into airline schedules covering 112 origin- destination city-pairs and their effect upon passenger volume. Two distinct markets emerged. Market A, the short-distance market, reflects a distinct set of traffic determinants which differ from those in Market B, the long-distance market. For Market A a significant relationship is shown to exist between traffic volume and the timing of schedules for the work-week days. This relationship did not appear for Market B. The results, however, lend support to the contention that with the advent of faster aircraft the long-distance market will reflect the same traffic determinants as are evident in today’s short-distance market. This indicates that scheduling in the long-distance market will become an increasingly important discretionary tool for airline management.

FRANK A. TILLMAN: A note on an iterative approach to multicopy trafic assignment. Transpn Res. 3, 75-78.

This paper illustrates a simple method for solving the multicopy traffic assignment problem. A less efficient method was proposed in an earlier paper for the multicopy problem. This approach simplifies the multicopy problem to that of a series of single copy problems.