The center for transportation studies

BibliographicSection based on the planner’s experience. Computer systems are used to sort the relevant data but they do not take an active part in the decision-making. Several authors have suggested the possibility of considering the interactions more globally and using mathematical programming techniques to solve the problem optimally. In spite of these efforts, the models proposed are little used. To obtain results for large networks, some authors sacrifice the representativity of their work with small networks. All these models have a common problem structure which makes them expensive to manipulate. With this structure, it seems impossible to deal with large networks in detail. This thesis proposes a new type of model which opens the way to a detailed analysis of large networks. This technology is based on an approach which has led to great advances in urban traffic planning in the last few years. This approach involves the use of nonlinear models which reflect reality more successfully and also greatly reduce the solution time required. The most important developments relate to the analysis of passenger flows. The treatment of the stochastic aspect of demand by the introduction of the expected number of passengers refused due to lack of space, has successfully replaced the use of a “load factor” to model the capacity limits of the aircraft. The use of this concept has led to the formulation of models with a more easily solvable problem structure. Four passenger distribution models are proposed. The first simple model uses the concept of excess passengers to model capacity constraints. This concept seems to be crucial as the results of this model are very good in spite of a rather simplistic treatment of the other factors. The second model introduces in addition the pluralistic behaviour of passengers. Rather than all trying to use the most attractive route, passengers distribute themselves between routes in proportion to their relative degrees of attraction. This third model reproduces the selfish behaviour of passengers (user optimization). Each passenger chooses his itinerary to maximize his own satisfaction without considering that of other passengers or the rational utilization of the network. The last model integrates the supply/demand equilibrium. Demand depends on the service provided, which depends on the availability of routes, which depends on passenger circulation. The solution methods to be used receive special attention in this thesis. The existence and uniqueness of the

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solutions are examined for each model. The problem structure permits solution by decomposition. The convergence of the decomposition procedure is demonstrated for each model. A very efficient algorithm has been developed for the solution of the sub-problems. The proof of its convergence and the order of this convergence are given. The first of the four models has been tested by Air Canada on a large network serving 76 cities with 329 flights daily. Tests on a previous season have enabled a comparison to be made between computed and observed aircraft utilisation. The mean absolute error on each flight-leg was eleven passengers. This accuracy compares very favourably with other models. A very important point to be stressed is that the computing time required was only 20 seconds for this large problem. The other three models have not yet been tested due to lack of data. These developments for the passenger problem allow the formulation of global models in which the interaction between passenger and aircraft flows is present only in the objective function. This formulation can then be solved using decompos$ion by taking the passenger and aircraft circulation components alternately. The passenger circulation component evaluates the flights offered by determining how the passengers will use them. The aircraft circulation component then takes this evaluation and modifies the aircraft flows to improve the benefits. This method gives integer solutions for the aircraft circulation problem but these are not necessarily optimal The method can however provide an improved feasible solution as it considers the impact in terms of costs and revenues in the entire network. A computer program for this method has been developed and tested on fictitious data. The solution times are satisfactory but the quality of the solutions produced by this suboptimal approach need to be evaluated for different types of networks. A great deal of work remains to be done in order to arrive at general software for the planning of an airline network. On the other hand, the technology proposed here represents an important advance in terms of its theoretical properties, the validity of the results and the computation time required. It has become possible to formulate a global model which can handle the essentials of a large problem in a reasonable time. It remains to develop methods for estimating the input parameters, to calibrate these models and to demonstrate their usefulness in a variety of practical situations.

SPECIAL FEATURE In line with our policy of drawing the readers’ attention to particular sources of research reports, we continue our occasional series on transportation research centers and their publications. Directors or leaders of such facilities are invited to provide us with descriptive materials on their activities, and to give us a list of their currently available publications.

for Transportation Studies, Room l-123, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, U.S.A. The Center

The Center is an Institute-wide facility designed to develop and coordinate interdisciplinary education and research among 50 faculty members from engineering,

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Bibliographic Section

economics, management, urban studies, political science and the social sciences. The Center was established in 1973 and is currently directed by Professor Daniel Roos. On the training front the Center organises mid-career courses for professionals and coordinates a new interdisciplinary Masters program in Transportation Studies. Research conducted by the full-time staff and by faculty associates is focused strongly on matters of transport policy. Among the projects underway is one dealing with transport-energy contingency planning, one with transport planning in Brazil, Egypt and Nigeria, and a recently negotiated project investigating the future of the automobile. Research completed at the Center is made available through a report series and through the MIT Press series in Transportation Studies. Titles available in the MIT Press series are The Automobile and the Environment (Edited by Ralph Gakenheimer, 1978), The Urban Transportation System (Alan Altshuler et al., 1979), Planning and Politics (Juri Pill, 1979)and Fundamentals of Transportation Systems Analysis (Marvin Manheim, 1979).In turn, these books were reviewed in this Journal in Volume 13A, No. 5.1979,~~. 367-368; Volume 14A,No. 3,1980,pp. 221-223; Volume 13A, No. 6, 1979, pp. 470-471, and Volume l3A, No. 6, 1979, pp. 467-468. Recent publications from the Center are listed below. Complete lists, as well as the publications themselves may be obtained by writing to the Center at the above address. Consolidation:

key to multimodal freight transportation,

Paul 0. Roberts, January 1978, CTS 78-3, pp. 41, $5.00. The emerging planning process: neither long-range nor short-range, but adaptive and (hopefully) decisive, Mar-

vin L. Manheim, January 1978, CTS 78-5, pp. 59, $6.00.

An approach for the evaluation of freight networks operations: a stochastic supply model of the regular route motor carrier industry, Marc N. Terziev, Frederick

W. Richardson and Paul 0. Roberts, February 1978,CTS 78-7, pp. 22, $5.00. Intermodalism and integrated transportation companies in the US and Canada, Ann F. Friedlaender and Ian

Harrington, October 1978, CTS 78-9, pp. 61, $6.50. The railroad rate structure and service innovation in the transportation of coal, Williams S. Kuttner, March 1978, CTS 78-10, pp. 88, $6.50. The tradeof

between railroad rates and service quality,

Paul 0. Roberts and A. S. Lang, May 1978, CTS 78-12, pp. 42, $5.00. Nigerian Ports Study:

trajic

studies and projection,

Bigosinski, January 1979, CTS 79-1, pp. 105, $8.00. Port congestion and analysis:

a short term perspective,

Daniel Shneerson, Fernando Bouthelier and Henry Marcus, January 1979, CTS 79-2, pp. 212, $11.00. Equity, ejiciency and resource allocation in the railroad regulated trucking industries, Ann F. Friedlaender and Richard H. Spady, March 1979, CTS 79-4, pp. 690, $20.00. The structure of the nation’s future freight system, Paul 0. Roberts, April 1979, CTS 79-6, pp. 37, $5.00.

INDEX OF NEW BOOKS 14:5:01

14:5:02

14:5:03

Banister Transport Teakf ield Bonavia Birth Allen

D

(1980) Mobility and Deprivation ISBN O-566-00307-4 pp212

M R (1980) of British Rail 8 Unwin ISBN O-04-385071-5

Bonavia M R (1980) The Four Great Rai lways David & Charles ISBN O-7153-7842-2

in $21

Inter-Urban .OO

Areas

$9.95

pp223

$17.50

14:5:04

Button K J.and The Economics Holmes & Meier

14:5:05

Christian J World Guide McGraw Hi I1

14:5:06

Condit C W (1980) Rai 1 The Port of New York : a History of the and System from the Beginnings to Pennsylvania Station University of Chicago Press ISBN 0-226-11460-O pp456

Pearman A D (1980) of Urban Freight Transport ISBN 0-8419-5060-i

M and Reibsamen G G (1980) to Battery Powered Road Transportation ISBN O-07-010790-4 pp392 849.50

Terminal $29.95