When transporting low density freight, some trucks “cube out” before reaching their maximum allowable weight. This creates demand for vehicles with higher cubic capacity for certain operations. Evidence of this can be seen in the significant increase in the number of WB-36 trucks (turnpike doubles) on Canadian roads. In recent years some jurisdictions have also begun to permit the use of extended trailers to address this issue, such as the 60’ extended trailers being piloted by the Ontario Ministry of Transportation. Ultimately, this creates a potential safety issue, when trucks larger than the current design vehicles are allowed to operate on existing infrastructure.
As freight movement demands and the use of large trucks increases it is important to ensure that existing infrastructure can accommodate these vehicles. Jurisdictions often attempt to accommodate trucks through geometric design; however, the benefits from these improvements can only be realised on newly constructed or retrofitted roadways. Conversely, modifications to the trucks themselves can improve their manoeuvring capabilities on all existing facilities. The objectives of this paper are to: (1) evaluate truck design modifications with respect to their effect on truck turning characteristics; and (2) investigate the capability of Winnipeg’s existing infrastructure to accommodate new truck and trailer configurations.
This paper was developed based on three key research tasks: (1) an environmental scan, consisting of a literature review and a jurisdictional survey, to determine factors that affect truck manoeuvrability, identify truck design modifications that improve manoeuvrability, and identify locations in Winnipeg that pose operational challenges for trucks; (2) analytical modeling of theoretical tractor-trailer combinations used in Winnipeg using AutoTURN turning simulation software to assess the effect of various design modifications on the vehicles’ turning characteristics; and (3) analytical modeling of truck configurations with extended trailers using AutoTURN turning simulation software to determine if they can be operated safely on Winnipeg’s existing infrastructure from an off-tracking perspective.
Analysis of the vehicle design modifications indicated the need for further analysis to determine if the positive impacts on safety attributable to increased manoeuverability outweigh the negative impacts associated with an increased front and rear swing out. Analysis of the extended trailer configurations indicated a need for field testing to determine if the difference in turning performance output by AutoTURN translates into practical differences for actual trucks on Winnipeg’s truck routes. However, since the extended trailer configuration outperformed the WB-36 with respect to turning performance, it is not hard to imagine a scenario in which extended trailer configurations are allowed to operate in Winnipeg under permit as long as they stay on preapproved routes, much like the WB-36 trucks are today.
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