Minton 1 BEHAVIOUR OF SUV AND MPV-TYPE VEHICLES IN COLLISIONS WITH ROADSIDE SAFETY BARRIERS

Roadside safety barriers are designed to deflect errant vehicles back onto the carriageway, preventing them from encountering potentially dangerous off-road hazards or crossing into the opposing carriageway on dual carriageways. However, there are concerns that SUVs and MPVs, by virtue of their greater mass and height, may not be well catered for by the current design of safety barrier, which is tested to withstand an impact with a 1500kg standard car. An analysis of National accident statistics (all police-reported injury accidents in Great Britain) is presented, which indicates that the occupants of these larger vehicles generally incur less severe injuries than occupants of standard cars. Only a small proportion of road accidents involve barrier strikes, and the involvement of a barrier is associated with increased likelihood of rollover and increased injury severity for occupants of all vehicle types. These increases in rollover incidence and injury severity are found to affect SUVs and MPVs much more than standard cars (rollover incidence rises by factors of 4 for cars, 7 for SUVs and 9 for MPVs). However, detailed information on a small number of barrier strike accidents involving SUVs or MPVs taken from TRL’s in-depth accident databases (10 cases in total) indicates that the barriers themselves may not be to blame. The barriers are found to exceed their design specification in a number of cases, and the cause of the accident is found in several cases to be difficulty in controlling these larger vehicles in extreme situations. Despite the limitations of a lack of detail in the national accident statistics and a small number of cases for in-depth analysis, this study nevertheless offers a useful insight into an accident scenario in which SUVs and MPVs become less safe for their own occupants than standard cars. INTRODUCTION Roadside safety barriers, also known as vehicle restraint systems, are designed to contain errant vehicles, preventing them from encountering potentially dangerous off-road hazards or crossing into the opposing carriageway on dual carriageways. However, there are concerns that Sports-Utility Vehicles (SUVs) and Multi-Purpose Vehicles (MPVs), by virtue of their greater mass and height, may not be well catered for by the current design of safety barrier in the UK, which is tested to withstand a 1500kg standard car impacting at 70mph (112kph) at an angle of 70. In terms of sales, the UK market share of SUVs has grown from 3% to 6% over the 15 years from 1990, and that of MPVs has more than doubled to a peak of 22% in 2001, though this has dropped back to 20% in the last few years. However, proportionately more SUVs are involved in accidents, which may imply that there are more of them in the vehicle fleet. This could be explained by the fact that SUV-type vehicles have existed for a long time, whereas MPV numbers are growing from a much smaller base. As a result of this increasing market penetration, any problems associated with the crash characteristics of these vehicle types are likely to grow as time goes on. We therefore set out to determine the nature of real world crashes involving these larger vehicles, to determine whether differences exist between their crash characteristics and those of standard cars, particularly when vehicle restraints are struck and, if so, to quantify the size of the problem. There is currently a shortage of information on vehicles of this type, which fall somewhere between cars and light goods vehicles (LGVs) in terms of size; indeed, some of the larger MPVs are little more than vans with windows and seats. However, in contrast to LGVs, which generally do not carry passengers, and which tend to be driven by professional drivers, the vehicles of interest are frequently used to transport families, so they have the potential to produce a greater number of casualties in any collision.