THE CAPACITY OF ROUNDABOUTS

Current methods of predicting the capacity of a roundabout are unsatisfactory. The premise adopted by the authors is that a roundabout operates as a series of linked t-junctions. The capacity is, therefore, controlled by a gap acceptance rather than weaving considerations. Conventional gap acceptance models were initially considered and developed to take into account the flaring of entries. The approach was further evolved into a consideration of such concepts as saturation flow and lost time, which led to a simplification of the final capacity equations. A multi-channel event recorder, used in the study, enabled a substantial amount of data to be collected and analysed. The results described clearly show that this priority type of approach is applicable to roundabouts, and the recommended design formulae are given. /Author/TRRL/

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  • Corporate Authors:

    Printerhall Limited

    29 Newmart Street
    London W1P 3PE,   England 
  • Authors:
    • McDonald, M
    • Armitage, D J
  • Publication Date: 1978-10

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00189531
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: N10
  • Files: ITRD, TRIS
  • Created Date: Apr 12 1979 12:00AM