The merging operation for car-following control is examined in which the speed and spacing of vehicles are regulated in response to a commanded line speed and the state (position and velocity) of the preceding vehicle. An algorithm for adaptive merging, capable of operating in discrete time intervals and which assures that no two vehicles ever follow the same vehicle, has been developed. The performance of the algorithm has been evaluated by means of a computer simulation capable of processing a large number of vehicles through a merge junction. Factors that may be varied in simulation include such operating characteristics as speed and headway, the level of traffic entering the system, the relative "bunchiness" of input flows, and the nominal speed-versus-spacing policy ot be followed by selection of the car-follow control gains. The study indicates that adaptive merging is a technically feasible and attractive approach to the merging problem when car-follower type longitudinal control is employed. Specific conclusions of the study are detialed: the length of the parallel data region ahead of the actual merge junction required to assure safe vehicle spacings when common line is reached is approximately equal to (2x nominal line speed) x (headway of the system); speed reductions for resolution of merge conflicts propagate upstream and downstream from the merge junction through the coupling effects of car-follower control; car-follower controllers may be designed to follow specific spacing-versus-speed policies; and for equal levels of combined downstream capacity, "bunchy" input flows were found to cause a greater variance in the magnitudes of maneuvers required to merge than smooth flows.

  • Availability:
  • Corporate Authors:

    Johns Hopkins University, Laurel

    Applied Physics Laboratory, 11100 Johns Hopkins Road
    Laurel, MD  United States  20723-6099
  • Authors:
    • Brown Jr, S J
  • Publication Date: 1974-10

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 79 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00098921
  • Record Type: Publication
  • Report/Paper Numbers: CP038/TPR 029 Final Rpt., UMTA-MD-06-0018-74-4
  • Contract Numbers: DOT-UT-30010
  • Files: TRIS
  • Created Date: Aug 13 1975 12:00AM