The American Association of State Highway and Transportation Officials (AASHTO) horizontal curve design policy focuses on driver comfort as a design criterion. AASHTO's driver comfort policy is based upon selecting a maximum amount of side friction in combination with a maximum amount of superelevation for a given design speed. AASHTO recommends using greater than minimum design values when practical. The purpose of this paper is to outline research that investigates if drivers are demanding a greater amount of side friction than provided by AASHTO in the low speed urban environment. The significance of reducing the minimum radius on horizontal curves could be realized in urban and suburban areas where developable space is typically restricted. If a designer knows that drivers are accepting higher values of side friction, then the designer could use a smaller minimum radius while still maintaining a sufficient margin of safety. By reducing the minimum radius, tighter alignments in smaller spaces could be accommodated, thereby increasing available space for development and possibly influencing speeds through a planned development.


  • English

Media Info

  • Pagination: 7p

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Filing Info

  • Accession Number: 00768860
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 15 1999 12:00AM