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13 from 1980 through 1983 to address these issues (8). The study Ministers Responsible for Transportation and Highway was developed with a clear intention that the research findings Safety at its meeting in September 1987. would be implemented. The study was funded jointly by all provinces and territories (50%), the federal government The Implementation Planning Subcommittee was formed (25%), and industry, as represented by the Motor Vehicle with one member from each province and territory. The chair- Manufacturers Association, the Canadian Trucking Associa- man was independent, and Transport Canada attended as an tion, the Truck Trailer Manufacturers Association, and the observer. Meetings were closed to stakeholders. Private Motor Truck Council (25%). The project was man- The CCMTA/RTAC Vehicle Weights and Dimensions Study aged through a small Technical Steering Committee made up provided a rational and objective means to define weight and of representatives of the funding partners. The CCMTA/ dimension parameters and vehicle configurations on the basis RTAC Vehicle Weights and Dimensions Study included: of considerations of vehicle dynamic performance and pave- ment loading (33). Previous work had established that bridge A simulation study of candidate-vehicle configurations (18), capacity would allow an increase in allowable weights (8), (9), (19), supported by a small amount of full-scale testing (19), but the provinces still had diverse approaches to assessment of and other assessments of simulation methodology (20), (21); the impacts of vehicles on bridges. The Implementation Plan- A full-scale test program (22), (23), supported by a simula- ning Subcommittee met with the provincial bridge engineers tion study to compare simulation results of test conditions as a group and achieved agreement on allowable axle group (24), and a specific examination of C-train stability (25); weights for defined spreads, for minimum inter-axle spacings An evaluation of rollover thresholds of heavy vehicles using necessary to maintain axle group weights, and for allowable a tilt table (26), supported by a study of simplified means gross weights. to assess the roll threshold (27); and The Implementation Planning Subcommittee developed A pavement test program (28), (29) and (30), supported detailed specifications for tractor-semitrailers from 3 to 6 axles, by an investigation of heavy truck suspension characteris- and A-, B-, and C-trains from 5 to 8 axles, which were con- tics (31). sidered the most common vehicles for interprovincial high- way transportation. The specifications included a drawing of After completion of the research, a technical seminar was the configuration, a table of dimensions, and a table of allow- held to report the findings to stakeholders. The work was also able weights. These specifications were necessarily detailed, to presented to the international community at the first Interna- ensure that pavement, bridge and dynamic performance were tional Symposium of Heavy Vehicle Weights and Dimensions all within acceptable limits. The specifications were attached (32). It is a measure of the significance of the CCMTA/RTAC to and formed part of the M.o.U., which was concluded in 1988 Vehicle Weights and Dimensions Study that this first sympo- at that year's meeting of the Council of Ministers Responsible sium has been followed by nine others, as the 10th International for Highway Safety. The M.o.U. was simply an understanding Symposium on Heavy Vehicle Transport Technology took that the ministers would make their best efforts to implement place in Paris during 2008. the content within their own jurisdiction (1). All provinces The Technical Steering Committee summarized the results have done this, without significant deviations. and developed a set of principles for configuration of vehicles The M.o.U. defined size and weight limits for tractor- based on the findings of the technical studies (33). semitrailers and A-, B-, and C-train double trailer combina- tions, and required each jurisdiction to allow vehicles within these limits to operate freely on a highway system designated 2.1.5 Development of National Standards, by that jurisdiction as suitable for operation of the vehicles. The 19861988 M.o.U. set the following axle group loads (1): After the research phase was completed, the CCMTA/RTAC Vehicle Weights and Dimensions Committee formed an Imple- 9,100 kg (20,061 lb) for a single axle; mentation Planning Subcommittee in 1986 with a charge to 17,000 kg (37,478 lb) for a tandem axle; and 21,000, 23,000 or 24,000 kg (46,296, 50,705 or 52,910 lb) Develop a plan that will assist each jurisdiction in imple- for a tridem axle with a spread of 2.44, 3.05 or 3.66 m (96, menting vehicle weight dimension and configuration regu- 120 or 144 in.), respectively. latory principles that will lead to national uniformity, Develop schedules for proposed implementation of recom- These axle loads were increases for the four western mendations, and provinces, but were generally consistent with, or less than, Monitor the progress of implementation of the recom- weights previously allowed in the six eastern provinces. There mendations as they may be agreed to by the Council of was essentially no effect on single and tandem semitrailers,