During the past 20 years, Canada has had a weight limit policy that has stipulated a variety of different weight limit regimes to the same truck type. This has provided an on-road experiment of how weight limits translate into actual truck weights. This experiment has created a large and unique data set that permits relating actual truck weights to governing weight limits spanning a broad range. On the basis of this data set, empirical models linking the distribution of gross vehicle weights (GVWs) of three of Canada's most common large truck combinations to the GVW limit governing these trucks are developed. They assume an idealized complete compliance condition, with no violation of the limit. The three truck types for which models are developed are the 5-axle (3-S2) tractor-semitrailer, the 7-axle (3-S2-2) B-train combination, and the 7-axle (3-S2-2) A-train combination. The complete compliance condition is of course violated if weight limits are not enforced or overweight operations are allowed by special permit. The predictive capability of the 3-S2 model is examined in relation to the GVW distribution of a sample of 3-S2s operating under a GVW limit different from those used in constructing the model. The predicted and actual distributions compare favorably. (A)
Abstract