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20 2.2 Provincial Truck Size and Weight Limits 2.2.1 The M.o.U. All provinces and territories have implemented Canada's national M.o.U. (34). Each province and territory allows a vehicle meeting the dimensional specifications of the M.o.U. to operate at a weight not more restrictive than specified in the M.o.U. on a road network specified by the province or ter- ritory. The vehicles may also be allowed to operate on other Figure 23. Ontario 131 SPIF 5-axle semitrailer. roads at lower weights, where roads, pavement or bridges may require that lesser weight. The M.o.U. defines configurations for 2.1.12 Summary In the late 1960s, Ontario introduced weight regulation Tractor-semitrailers, from 3 to 6 axles; based only on a complex bridge formula, which allowed a A-train doubles, from 5 to 8 axles; substantial improvement in truck productivity but also cre- B-train doubles, from 5 to 8 axles; ated many unintended consequences. The regulation had no C-train doubles, from 5 to 8 axles; controls on axle or vehicle configuration, and a wide range of A straight truck, with 2 or 3 axles; configurations came into use with widely spaced liftable axles, A truck-pony trailer, from 3 to 6 axles; many of which also had poor dynamic performance and were A truck-full trailer, from 4 to 7 axles; and ultimately shown to have a serious and very detrimental impact An intercity bus, with 2 or 3 axles. on roads and bridges. This was compounded when a change in the form of regulation allowed weights above the bridge for- The M.o.U. provides that the maximum overall length for a mula, and length increases intended for compatibility with U.S. tandem semitrailers also allowed new and heavier con- Tractor-semitrailer is 23 m (75 ft 6 in.); figurations. This approach, where vehicle configuration was A-, B- or C-train double is 25 m (82 ft); not specified, resulted in significant outcomes that were both Straight truck is 12.5 m (41 ft); unexpected and undesirable. Truck-trailer combination is 23 m (75 ft 6 in.); and The large discrepancy in size and weight regulation among Intercity bus is 14.0 m (46 ft). the Canadian provinces and the transportation inefficiencies rapidly became a barrier to internal trade. The provinces together, supported by the federal government and industry, The maximum length for a semitrailer is 16.20 m (53 ft), sponsored a research program to identify the significant issues and for a pony trailer or full trailer is 12.5 m (41 ft). There of truck size and weight regulation. This allowed vehicles to are a considerable number of internal dimensional limits be configured on the basis on objective standards for dynamic for vehicles and combinations, primarily to ensure adequate performance. Detailed specifications that control internal dynamic performance. dimensions found in the M.o.U. are necessary for this and The M.o.U. provides for an allowable axle load of have generally resulted in the desired outcomes. Vehicle configurations have been monitored closely since 5,500 kg (12,125 lb) for the steer axle of a tractor; the M.o.U. to ensure that the rules are resulting in the desired 7,250 kg (15,983 lb) for the steer axle of a straight truck; outcomes. When a loophole is evidently allowing configura- 17,000 kg (37,478 lb) for a tandem axle; tions with undesirable properties, the rules are changed as 21,000 kg (46,296 lb) for a tridem axle with a spread from quickly as possible to close the loophole before those config- 2.4 to 3.0 m (94 to 118 in.); urations become widely used and popular. 23,000 kg (50,705 lb) for a tridem axle with a spread from Provinces have continued to develop other configurations 3.0 to 3.6 m (118 to 142 in.); and beyond those defined in the M.o.U. for domestic use, or for 24,000 kg (52,910 lb) for a tridem axle with a spread from use with an adjoining jurisdiction, for operation either in reg- 3.6 to 3.7 m (142 to 146 in.). ulation or by special permit. All provinces include an assess- ment of the dynamic performance of any proposed or new The six eastern provinces allow 18,000 kg (39,682 lb) on a configuration as part of the assessment of cost and benefit of tandem axle, and 26,000 kg (57,320 lb) for a tridem axle with that configuration. a spread from 3.6 to 3.7 m (142 to 146 in.).