DESIGN OF FREEWAY ENTRANCE RAMPS AND LANE DROPS BY USING SEMI-MARKOV PROCESSES (ABRIDGMENT)

A continuous-time semi-Markov highway model can be used to simulate and design highway situations that require a merging manuever. A general continuous-time semi-Markov model can be used to simulate a number of merging situations by the substitution of appropriate values for the design parameters. The substitutions are made into established general formulas. The continuous-time semi-Markov process can then be analyzed with flow graph and Laplace transform techniques. The design parameters included in the model are freeway vehicle headway distributions, lane volumes, lane running speeds, and a gap acceptance function that describes a driver's willingness to accept a given headway in an adjacent lane. The continuous-time semi-Markov model can be used to find the distribution of the time spent by a driver waiting to emerge from an entrance ramp. This distribution can be used to evaluate the freeway entrance ramp designs. The effect of improved visibility on waiting time, for example, could be studied by using the waiting time distribution. Different gap acceptance functions can be used to reflect the effect of improved visibility on a typical driver's merging behavior. The location of a warning that a freeway lane drop is imminent can also be studied by means of a continuous-time semi-Markov model. Design contitions can then be calculated. This proportion can be related to the level-of-service concept. Further work is required before a definitive relation can be established between the output of a semi-Markov model and levels of service as those levels are currently defined.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/trr/1976/596/596-002.pdf
• Summary URL:
  http://scholar.google.com/scholar_lookup?title=DESIGN+OF+FREEWAY+ENTRANCE+RAMPS+AND+LANE+DROPS+BY+USING+SEMI-MARKOV+PROCESSES+(ABRIDGMENT)&author=R.+Abella&author=D.+COLONY&author=J.+Hansell&publication_year=1976
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/03611981
• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Traffic Flow Theory and Characteristics. 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.
• Authors:
  • Abella, Robert J
  • COLONY, DAVID C
  • Hansell, John D
• Publication Date: 1976

Media Info

• Media Type: Digital/other
• Features: Figures; References;
• Pagination: pp 3-5
• Monograph Title: Flow theory
• Serial:
  • Transportation Research Record
  • Issue Number: 596
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Freeways; Gap acceptance; Highway design; Interchange ramps; Lane drops; Markov processes; Merging traffic; Visibility
• Old TRIS Terms: Freeway design models; Freeway entrances and exits; Freeway ramps; Lead angle
• Subject Areas: Design; Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00149113
• Record Type: Publication
• ISBN: 0309025656
• Files: TRIS, TRB
• Created Date: Apr 13 1977 12:00AM