CAPACITY OF 2-LANE ROADS: A REVIEW OF CHANGES IN US HIGHWAY CAPACITY MANUAL

This document identifies new capacity rating procedures for 2-lane roads proposed in the US highway capacity manual (1985) and draws comparisons with the previous manual (1965) and with Irish procedures as set down in an foras forbartha guideline rt 180. Changes include the method of identifying level of service in the field, the way in which the design hour traffic volume is arrived at and the amount of traffic appropriate to each level of service and road situation. The new method of identifying level of service in the field is claimed to be simpler and more reliable; the new derivation method for design hour traffic produces higher values for design but generally the effect is more than offset at the lowest levels of service where considerably increased traffic volumes are now acceptable. The document mentions three features of concern in the Irish context which have not yet received consideration in the hcm. (Author/TRRL)

• Corporate Authors:

  National Institute for Phys Planning & Constr Res

  St Martin's House, Waterloo Road
  Dublin 4,   Ireland 
• Authors:
  • McGuinness, P
• Publication Date: 1986-10

Media Info

• Features: References;
• Pagination: 11 p.

Subject/Index Terms

• TRT Terms: Highway capacity; Level of service; Manuals; Traffic volume; Two lane highways
• ITRD Terms: 6464: Calculation; 643: Capacity (road, footway); 9011: Design (overall design); 635: Design speed; 2755: Highway; 9030: Hour; 6226: In situ; 8049: Ireland; 653: Level of service; 1236: Lorry; 9102: Method; 1822: Overtaking; 8526: Textbook; 671: Traffic flow; 2827: Traffic lane; 9082: Two; 8122: USA; 6793: Visibility distance; 6479: Width
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00470614
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD, TRIS, ATRI
• Created Date: Aug 31 1988 12:00AM