Criteria for the Selection of a Left-Turn Median Design

Details

• Creators:
  Modur, Sanjay ; Machemehl, Randy B. ; Lee, Clyde E.
• Corporate Creators:
  University of Texas at Austin. Center for Transportation Research
• Corporate Contributors:
  Texas State Department of Highways and Public Transportation ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  Bays Combinations Geometric Distributions Geometric Treatment Guidelines Left Turn Lanes Median Lanes Operational Criteria Operations Streets Urban Highways

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• Publication/ Report Number:
  FHWA/TX-90+1138-1F
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas ; United States
• Edition:
  Final Report
• Corporate Publisher:
  University of Texas at Austin. Center for Transportation Research
• Abstract:
  At least six different median design combinations can be utilized to serve the traffic demands of suburban streets and highways. These range from raised to flush medians with or without left-turn bays, continuous left-turn lanes, or no left-turn geometric treatment. Virtually all of these are commonly used by the aggregate of geometric designers in the United States; however, there is less than complete agreement regarding the conditions under which each is most appropriate. This research study developed guidelines for median design based upon dual considerations of accident experience and operational considerations. Operational criteria address two, sometimes conflicting, design objectives which are maximization of flow and minimization of traffic delay. Key variables employed in the criteria include the magnitudes of straight through and left-turn traffic demands types of development adjacent to the street section, and operating speeds. The quality of traffic service provided by a street or highway is usually heavily influenced by the performance and number of intersections along the section. Streets that have intermittent curb cuts or driveways and a traffic demand for left-turns into these driveways might be viewed as having pseudo intersections at all locations where left-turns are permitted across the median into driveways. Median designs were found to have a strong impact upon the operations of most real and pseudo intersections and therefore, upon most street sections.
• Format:
  PDF
• Funding:
  3-8-88-1138
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:95282a33f96ad6b9dc0c1a3cf8804f2477c62a569cc08edab84daf57e16b32cc6c4b4200d874ec49bab48988a0e2e3d0835ea18a896a4969869d742672ca73d4
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/86109/dot_86109_DS1.pdf
• File Type:
  [PDF - 2.22 MB ]