This report presents a method for establishing lane width dimensional limits for heavy vehicles travelling on straight paths that is based on computer modelling. Full-scale tests of the tracking behaviour of an A-double are described that were used to verify and validate the predictions from a computer model of the same vehicle. Separate computer models were then created, and the tracking behaviour and lane width requirements determined for the following range of generic heavy vehicles: 19m prime-mover/semi-trailer; 3-axle truck and 3-axle and 4-axle dog trailer combinations; A-double; A-triple; 19m and 25m B-doubles; B-triple; and rigid-plus-three. These generic heavy vehicle models are worst-case types operating under worst-case conditions to produce maximum lateral displacements. The aim was to determine dimensional limits on tracking for heavy vehicles following straight paths that would cover all possible situations that might occur under the current mass and volume loading schedules. The research found tracking ability was principally dependent on road cross-slope profile, vehicle configuration and length, and speed. All of the vehicles investigated could travel comfortably along roads that have a useable lane width of 3.5m except for the A-triple and the rigid-plus-three operating at the higher of the two speeds investigated (90km/h). The traditional measure of road surface unevenness did not correlate well with tracking performance. A performance-based method of assessing heavy vehicles for route access using state-of-the-art computer modelling techniques has been successfully demonstrated. (A) This report is the result of work commissioned under contract by Austroads as part of its National Strategic Research Program (NSRP).
Samenvatting