Since the publication of the latest edition of the Highway Capacity Manual (HCM) in the USA in 1985, there has been renewed interest in techniques for analysing unsignalised intersections. As a result, some additional steps have been taken in the USA to (1) review the validity of the theoretical results when applied to field conditions; (2) take an additional look at previous and ongoing research activities; (3) compare the results of various new techniques; (4) identify specific areas where additional research is needed. This paper presents the results of these activities by summarising the status of unsignalised intersection capacity research in the USA; it has been prepared by representatives from the Unsignalized Intersection Subcommittee of the Transportation Research Board Committee on highway capacity and quality of service. It discusses (1) the existing unsignalized intersection capacity technique used in the USA; (2) the American user community's experience in applying the HCM techniques; (3) previous and ongoing US research activities; (4) a detailed comparison of the results of the 1985 HCM techniques and the current German technique. Finally, it briefly describes the Committee's four proposed areas of research on the capacity of unsignalised intersections:(1) new capacity methods for cross-street stop and yield controlled intersections; (2) multiway stop-controlled intersection capacity; (3) the relationship between levels of service and traffic signal warrants; (4) design and planning methodologies for unsignalised intersections.
Abstract