FIELD OBSERVATIONS OF PATH AND SPEED OF MOTORISTS AT DOUBLE-LANE ROUNDABOUTS

Roundabouts generally have fewer crashes and less severe crashes compared to signalized intersections. Reduced speed and low speed differences between entering and circulating traffic are thought to be important contributors to roundabout safety. The geometric design of modern roundabouts has many attributes that may influence drivers' selection of path and speed. Deflection at entry is one of the attributes that contributes to both the reduced speeds and low speed differences. The Federal Highway Administration (FHWA) publication "Roundabouts: An Informational Guide" suggests a method, based on the theoretical fastest path, for evaluating geometric designs for adequacy in controlling speed and speed differences. The current study evaluated that method against observations of path and speed at two double-lane roundabouts. The results suggest that the method given in the FHWA publication predicts actual operational speed fairly well. A method is described for recording speed and path through approach, circulatory roadway, and departure. This method provides for economical recording of lane position at five locations along a through path, and spot speed at three locations.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References; Tables;
  • Pagination: 16p
  • Monograph Title: 2ND URBAN STREET SYMPOSIUM: UPTOWN, DOWNTOWN, OR SMALL TOWN: DESIGNING URBAN STREETS THAT WORK, JULY 28-30, 2003, ANAHEIM, CALIFORNIA

Subject/Index Terms

Filing Info

  • Accession Number: 00989167
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Apr 8 2005 12:00AM