COMPUTER COORDINATION OF TRAFFIC SIGNAL SYSTEMS

In May 1973, the Utah State Department of Highways commissioned Dr. William J. Kennedy, of the University of Utah, to create or obtain a simulation model for traffic flow in signal-controlled roadway networks. The Federal Highway Administration had such a model, the UTCS-1 (Urban Traffic Control System 1) computer program, but this program had not been applied by any state highway department. The program was obtained, and a network around the intersection of 3500 South and Redwood Road in Salt Lake County was selected for the first trial. On August 2, 1973, vehicle counts were obtained for the vehicles entering and leaving this network during the morning and evening peak periods. These counts, and resulting calculated flow rates, were then used as a basis for statistical comparison between the model and the actual traffic flow after suitable data input formats had been developed. The comparison showed no statistically significant difference between the model volumes and the observed volumes, hence it was decided that the UTCS-1 model could validly be applied to Utah traffic problems. One such application was the interchange between Interstate I-15 and 4500 South. This interchange, one of the most congested in Utah, was modeled, using data gathered on October 2, 1973. Two different proposed signal timing plans were applied to the model of the network, either reducing cycle times by half or making all traffic signals fully coordinated. Both plans indicated marked reductions in delay and substantial increases in average speed through the network. Since the first alternative was less expensive to implement, it was tried at the interchange, and congestion was observed to decrease, as predicted. It appears that this modeling technique gives traffic engineers a potentially valuable tool for predicting the effects of implementing new traffic plans and for trying several such plans without the political consequences attendant upon failure.

  • Corporate Authors:

    Utah Department of Transportation

    Traffic Engineering Division
    Salt Lake City, UT  United States  84114

    University of Utah, Salt Lake City

    307 Park Building
    Salt Lake City, UT  United States  84112
  • Authors:
    • Kennedy Jr, W J
    • Farr, R M
    • Labrum, W D
  • Publication Date: 1974-3

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 31 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00260440
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Oct 11 1974 12:00AM