00624761

Component

http://onlinepubs.trb.org...trr/1992/1333/1333-007.pdf

https://scholar.google.co...feld&publication_year=1992

A numerical method has been developed for estimating delays on congested waterways represented by series of G/G/1 queues (i.e., with generally distributed arrival and service times and one chamber per lock). It is based on a metamodeling approach that develops simple formulas to approximate the results of simulation models. The functional form of the metamodels is derived from queueing theory, whereas their coefficients are statistically estimated from simulation results. The algorithm scans along a waterway and sequentially estimates at each lock the arrival distributions, departure distributions, and delays. It can be applied to systems with two-way traffic through common bidirectional servers as well as to one-way traffic systems. Computational results are presented to illustrate the speed and convergence properties of the algorithm and to investigate some of its variants. The algorithm works satisfactorily and flexibly with different convergence criteria and scanning processes. For an illustrative 20-lock system, parameter estimates converge with five iterations and less than 3 sec of CPU time to differences lower than 0.1% between successive iterations. The computation time increases only linearly with the number of locks in the system, thus allowing the analysis of very large systems of interdependent queues.

This paper appears in Transportation Research Record No. 1333, Marine and Intermodal Transportation: Freight Movement and Environmental Issues. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01407209

English

p. 45-54

1992

Transportation Research Record

030905172X

Figures (3) ; References (16) ; Tables (8)

Algorithms; Delays; Estimating; Locks (Waterways); Queuing; Traffic congestion; Traffic delays; Waterways

Congestion; Metamodels

Highways; Marine Transportation; Operations and Traffic Management

TRIS, TRB

Aug 3 1993 12:00AM

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