Abstract
This paper describes an investigation of the effects of safety chains on the dynamics of truck and full trailer combinations in the event of a catastrophic failure of the primary pin coupling. Safety chains on drawbar couplings are not mandatory in Australia for truck and full trailer combinations but are recognized as having the potential to reduce the crash risk and the severity of crash outcomes. Some industry stakeholders, predominantly drivers, have expressed safety-related concerns about the potential unintended effects of the chains on the dynamics of the hauling unit in the event of a coupling failure. The on-road dynamics of truck and full trailer combinations connected only by safety chains was assessed in various scenarios through field tests of several driving maneuvers, in which dynamic performance data were recorded by a data-logging system. Through the analysis of the recorded data and observations made by the driver of the vehicle and other observers, it was found that neither the truck nor the trailer demonstrated unsafe behavior in any of the tested maneuvers. It was determined that a truck–trailer combination could be brought safely to a stop in the event of a primary connection failure, up to the highest tested speed of 80 km/h (50 mph). These findings strongly indicate that there is little potential for safety concerns to arise as a result of fitting safety chains to the drawbar couplings of these truck configurations.
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