During the construction of a crawler lane at two gradients on M5 motorway in 1975, two lanes were kept open to traffic up the gradient by re-marking the carriageway with sub-standard lane widths. The effects of the reduced lane widths on traffic flow were minimal, although advisory speed limits on the sites probably reduced the speed of traffic on the gradients and their approaches. The traffic delays averaged only 12 veh-h/h when the narrow lanes were operating. Later in the work, lane closures and two-way operation restricted the uphill traffic to only one lane and produced considerable delays as a result (up to 112 veh-h/h). Consequently, when it was necessary to close one of the carriageways during the final stages of the work, a system of two-way operation using narrow lanes was implemented. This system provided two lanes for traffic up the gradients, and reduced to delays to 53 veh-h/h.

  • Corporate Authors:

    Transport and Road Research Laboratory (TRRL)

    Wokingham, Berkshire  United Kingdom 
  • Authors:
    • MacLean, A D
    • Greenway, M
  • Publication Date: 1977

Media Info

  • Features: Figures; Photos; Tables;
  • Pagination: 14 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00164400
  • Record Type: Publication
  • Report/Paper Numbers: TRRL Lab Rpt. 782
  • Files: TRIS, ATRI
  • Created Date: Dec 8 1977 12:00AM