The objective of this research was to investigate and compare the safety, operational, and cost characteristics of selected multilane design alternatives for suburban highways. Operational characteristics of interest to the study included capacity, level of service, and accessibility. Safety characteristics included the frequency, severity, and type of accidents. The multilane design alternatives that were the major focus of the research included: three-lane divided including a two-way left-turn lane in the median; four-lane undivided; four-lane undivided; four-lane divided with a raised-median; and five-lane divided including a two-way left-turn in the median. Other multilane design alternatives that were considered in the study included: five-lane divided with a continuous alternating left-turn lane in the median; six-lane divided with a raised median; and seven-lane divided with a two-way left-turn in thh median. A two-lane undivided suburban highway served as the base condition for the study. A safety data base was assembled for suburban highways on the state highway systems of California and Michigan to quantify the safety performance of multilane design alernatives. Accident rate estimates and the percentage of accidents involving a fatality or injury and the percentage of accidents susceptible to correction by median treatments were also quantified by design alternative and type of development. Traffic operational comparisons of suburban highway sections with and without two-way left-turn lanes were made using a computer traffic simulation model. The research provides a comparison of the advantages, disadvantages, and relative merits of the various design alternatives for suburban highways, including both their traffic operational and safety performance, as well as the less quantitative aspects such as the impacts on land use and development, abutting businesses, and pedestrians and bicycles. A stepwise process for selecting an appropriate design alternative for use on a suburban highway is suggested.

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    • 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.
  • Corporate Authors:

    Transportation Research Board

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  • Authors:
    • Harwood, D W
  • Publication Date: 1986-3

Media Info

  • Media Type: Digital/other
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 71 p.
  • Serial:
    • NCHRP Report
    • Issue Number: 282
    • Publisher: Transportation Research Board
    • ISSN: 0077-5614

Subject/Index Terms

Filing Info

  • Accession Number: 00454530
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Jul 31 1988 12:00AM