Good design practice requires that the geometric layout of an intersection be checked to ensure that it can accommodate the class of vehicle that will be using the road system. The physical characteristics and dimensions of representative vehicles are positive controls for the intersection design. The design vehicle dimensions referenced in the current version of the Geometric Design Guide for Canadian Roads are inappropriate. Some are outdated, having been unchanged since 1965, and some are overly conservative, being based on maximum legal dimensions rather than typical design dimensions. The objective of this study was to undertake a comprehensive review of the current practices and recommend new design vehicle standards to be used in an update for the Guide. The report, Design Vehicle Dimensions for Use in Geometric Design, provides general background information relating to the theory of offtracking and describes the current (TAC/AASHTO) vehicle classes/dimensions used for geometric design purposes. The results of literature reviews and information obtained from various contacts are summarized and the merits/demerits of potential data sources for use in this study are discussed. Further details of the data sources elected for this study are given and the results of the data analysis along with final recommendations pertaining to design vehicle classes and their dimensions are presented. (A)
Abstract