Turning characteristics of large trucks, such as offtracking (the difference in paths of the front-most and rear-most inside wheels of a vehicle as it negotiates a turn) and swept-path width (the amount of offtracking plus the width of the truck), require special consideration in the design of at-grade intersections. Five large truck combinations, representative of the longer and wider trucks permitted by the Surface Transportation Assistance Act of 1982, were selected and their paths computer-simulated traversing different turning radii at several angles of turn. The findings were tabulated as guidelines for intersection channelization designed to accommodate these longer and wider trucks. The results include several specific truck turning templates; tables containing cross-street width occupied and swept-path width for various combinations of design vehicle, curb radii, and degree of turn; and recommended guidelines that illustrate conditions where channelization is feasible when designing for larger trucks. These guidelines include the minimum required curb radii to eliminate encroachment into either opposing or adjacent traffic lanes on the cross-street, the minimum required width of turning roadway, and the approximate size of the space available for.
Abstract