Several algorithms exist to implement a change between fixed-time signal plans. These are reviewed and the constraints influencing the process of change are examined. A comparison of actual networks reveals the daily and cyclical variations in flow which prevail in practice and within which the plan-changing process must be seen. Studies using TRANSYT are reported and finally 5 plan-change algorithms are assessed against an "ideal" plan-change, using Monte Carlo simulation techniques. The results suggest that significantly less delay (at the 5% level) and fewer stops are incurred when plan-changes are implemented at off-peak rather than at peak flows. The MODIFIED ABRUPT algorithm (commonly called CRASH), which is in common use, is found to generate no statistically significant (at the 5% level) additional stops or vehicular delay on main roads, irrespective of the level of flow at which the plan-change is made and whether the change is from off-peak to peak or vice versa. The variation in delay caused by implementing a plan-change with the MODIFIED ABRUPT method is found to be less than 2%. It is concluded that plan-changes should always be implemented during off-peak flow conditions and that the commonly used MODIFIED ABRUPT algorithm is the most satisfactory method under prevailing constraints. (Author)

  • Corporate Authors:

    Newcastle upon Tyne University, England

    Transport Operations Research Group, Claremont Road
    Newcastle NE1 7RU, Tyne and Wear,   England 
  • Authors:
    • BELL, M C
    • GAULT, H E
    • Taylor, I G
  • Publication Date: 1983-4

Media Info

  • Pagination: 49 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00386726
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Jul 30 1984 12:00AM