Assessing the roll stability of heavy vehicles in South Africa

Abstract

In South Africa there are approximately 12.5 truck-crash-related fatalities per 100 million kilometres travelled. This is between 4 and 10 times higher than a number of European countries such as Denmark, France, Germany and Switzerland and many of these crashes involve heavy vehicle rollover. The regulations in the National Road Traffic Act of South Africa that govern heavy vehicle design do not directly address the roll stability of heavy vehicles. The internationally accepted method of regulating roll stability is by means of a static rollover threshold (SRT) assessment or test, to determine the maximum lateral acceleration that a vehicle can withstand before rolling over. The SRT is determined by physical testing, or through multibody dynamics simulation; however both of these approaches are costly and time-consuming. This paper considers various simplified tools to estimate the SRT of articulated heavy vehicles, and compares the results to SRT values determined using multibody dynamics simulation. The simplified tool as described by the New Zealand Land Transport Rule was identified as the most viable technique to potentially regulate the roll stability of heavy vehicles in South Africa.