The communications requirements of dual-mode transportation systems are discussed for both the on-guideway and off-guideway modes. Candidate communication systems are classified according to their principle of operation, and the characteristics of the systems are described. The suitability of these systems is assessed on the basis of dual-mode requirements, Federal Communication Commission restrictions, and physical and electrical limitations. Command and control for vehicles on the guideway are the most critical functions that the communication system supports and require a highly reliable, always available, link. The possible communication links are narrowed to nonradiating and contact systems within the FCC limits for unlicensed devices. Nonradiating systems of the surface-wave type are suitable only if rather stringent limits on lateral vehicle motion and guideway turning radius are satisfied. Communication through direct contact with a signal rail is generally justified only for systems in which the supporting structure for the rail and the vehicle contact arm have an independent reason for existence. Such systems include those in which vehicles are powered from a wayside rail and those that use an arm in lateral control. The technique of superimposing communication signals on the power rail is likely to be prohibitively expensive. If supporting structures are counted as a part of the system, inductive systems can be expected to be less expensive than contact systems. Most commonly, inductive lines used for communications are buried in the roadway; and, if the command and control system uses inductive fields to detect lateral vehicle motion, it is sometimes possible to satisfy the detection and communication functions with the same inductive lines. In the off-guideway mode, vehicles are not confined to a relatively small number of arteries consequently, a communications system with broad coverage is needed. Radiating line sources installed along all possible routes may be technically feasible, but are an inefficient and expensive means of general coverage. Clearly, the best method of providing off-guideway communications is through conventional localized antennas.

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    • This article appeared in Transportation Research Board Special Report 170, Dual Mode Transportation, which is the proceedings of a conference conducted by the Transportation Research Board, May 29-31, 1974.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
  • Corporate Authors:

    Transportation Research Board (TRB)

    Washington, DC   
  • Authors:
    • Eaves, Reuben E
    • Kodis, Ralph D
  • Conference:
  • Publication Date: 1976

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  • Accession Number: 00159901
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Sep 28 1977 12:00AM