To cope with serious traffic congestion on streets in the City of Boston, Massachusetts, a traffic signal control system which serves the demands of both private vehicles and public transit is being implemented. The initial project provides for control of Massachusetts Avenue, a principal north-south arterial in Boston. All phases of the system will be under the supervision of the central computer located in a control center in Boston City Hall. The project is designed for expansion to include other locations, and Commonwealth Avenue is currently being added to the system. The nature of traffic operations on city streets requires that the control system be flexible to respond to the irrational and often unpredictable demands and conditions that occur, including double and triple parking. To provide this flexibility the system has been designed for alternative modes of operation, with changes and variations to these modes programmed as software items in the computer. A daily statistical printout, both tabular and graphic, with be produced automatically giving volume, occupancy, speed and stop data. In addition, the central control will have the capability of monitoring local controllers, sampling detectors, and stop-line presence detectors to determine whether they are functioning normally. Special detection equipment senses the movement of buses on Massachusetts Avenue and the central control computer then adjusts the timing of signals to accelerate traffic flow in approaches occupied by buses. In Commonwealth Avenue the system will include priority for street cars (trolley cars and light rail vehicles) which operate in the median. New trolley priority hardware and control logic have been developed for the Commonwealth Avenue trolley line. The control logic, uses two specially designed features to facilitate trolley movements through signalized intersections and eliminate conflicts with normal street traffic. Phase flipping is built into traffic signal controllers which permit the transit vehicle to effect changes in phasing in order to allow the traffic computer an additional degree of freedom. The second unique feature of the control logic is use of successively updated and narrowed predictions of trolley car arrival in a time window at downstream intersections with far side transit stops. /Author/

  • Availability:
  • Supplemental Notes:
    • This paper was presented at the 8th IRF World Meeting, Tokyo, Japan, October 16-21, 1977. Full text also written in Japanese.
  • Corporate Authors:

    International Road Federation

    525 School Street, SW
    Washington, DC  United States  20024
  • Authors:
    • Brant Jr, A E
    • Casper, G W
  • Publication Date: 1977-10

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Filing Info

  • Accession Number: 00179843
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 12 1982 12:00AM