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11 Figure 4. Ontario tri-axle semitrailer from the early 1970s. Figure 7. Ontario A-train double from the early 1970s. The allowable gross weight of a vehicle under the OBF had to be evaluated by extensive manual calculations using a work- sheet and tables. It was difficult, time consuming, and perhaps too complex for some enforcement staff at truck inspection stations and for carriers to perform these calculations. A reg- ulation was therefore developed that provided "look-up" tables that gave allowable gross weights for ranges of axle spac- ing of the most common configurations. The industry quickly Figure 5. Ontario 4-axle semitrailer from the early realized that weight enforcement would not be possible if a 1970s. configuration was not covered in the regulation so many new and unusual configurations were developed. These examples show the forces that drive unintended consequences. with widely spaced axles, as shown in Figure 4 and Figure 5, with one or more liftable axles, truck-trailer combinations, as shown in Figure 6, and double trailer combinations, as shown 2.1.3 Intermediate Steps, 19701982 in Figure 7 and Figure 8. The new configurations provided Trade restrictions made it efficient for U.S. manufacturers industries shipping heavy or bulk commodities with a signif- to establish branch plants in Canada, and to distribute the icant improvement in transportation productivity (7). The products in Canada by truck and rail. Freight transportation failure to control axle arrangement or vehicle configuration in Canada was therefore primarily eastwest in this period. may have been an oversight, though there is some evidence of Ontario's axle weight increases in 1970, and the resulting an intention to allow truck designers to innovate (3), though large gross weight increase, put pressure on other provinces there may have been little idea as to where this innovation for similar changes. might lead. The growth in use of liftable axles, and their con- The other provinces increased maximum gross weight lim- sequences in damage to the infrastructure, were not foreseen. its during the 1970s, to between 49,900 kg (110,000 lb) and The rest of this story is really about the years of effort needed 57,150 kg (126,000 lb). Unlike Ontario, these provinces all to undo this step. provided a prescriptive specification for vehicle configuration Figure 6. Ontario truck-trailer combination from the Figure 8. Ontario B-train double from the early early 1970s. 1970s.