The Dynamic Behavior of Heavy Vehicles in Cornering Actions: An Assessment of the Problem

Road accidents cause 1.3 million deaths annually, motivating the United Nations (UN) to develop a strategy seeking to halve this number by 2030. Portugal, with 60 deaths per million inhabitants in 2022, ranks sixth in European Union (EU) road fatalities, although these numbers have been decreasing since 2010. Rollover accidents account for 33% of traffic fatalities in the U.S.; yet, only 3% of crashes involve rollover accidents. These are particularly dangerous and mainly involve medium-to-large-sized vehicles having high centers of gravity (CoG), such as SUVs and heavy vehicles. On the other hand, bus accidents make up only 2% of EU road deaths, often involving vulnerable road users. Road forensic investigations rely on CoG positioning data for accurate accident reconstructions, using key equations for calculating skid and overturning speed limits. To complement the already existing equations, and by using a rigid body system, an equation for the evaluation of the overturning velocity in a curved trajectory is developed and proposed, considering the suspension stiffness properties of a vehicle. Finally, a real-world accident investigation involving a bus overturning is presented, and the method that was developed is applied. The developed formulation showed good results compared to the ones that were obtained during the forensic investigation and reduced the error from 5% to 2% compared to the existing equations.