The Transport and Road Research Laboratory (TRRL) has conducted trials on a range of four wheel drive multi-purpose vehicles to investigate their tendency to overturn when used on the road. The suitability of various test methods were also assessed. Static tests were carried out on a tilt platform to measure the tilt angle at the point of balance for each vehicle. Two lane change manoeuvres and a J-turn test were used to assess the dynamic handling performance in simulated emergency situations. There was some correlation between tilt test results and the tendency towards overturning seen in the dynamic tests, especially in the J-test, but it was not very strong. Driver influence compromises the goal of a repeatable test procedure, an automated J-turn test being a possible solution. Any test procedure should be representative of real-life driving situations. In developing such a procedure, care is needed in defining the acceptable limits of roll-over behaviour. An alternative approach is to concede that such multi-purpose vehicles, because of their relatively high centre of gravity, are more likely to overturn than cars. In this case the occupant protection they offer may need to be improved through the provision of better internal roll-over protection and by encouraging greater use of seat belts.
Abstract