4x4s more likely to roll in crashesResearchers say its due to high centre of gravity

06 February 2007

Large four-wheel-drive vehicles are more likely than other cars to roll over in crashes because of their higher centre of gravity, researchers have found.

‘Chelsea Tractors’ are particularly unsafe if they hit motorway barriers, experts from the government's Transport Research Laboratory discovered.

Their larger mass and higher centre of gravity, which many parents feel is a safety plus, in fact make them more likely to run out of control if they hit an object or swerve suddenly.

Researchers Roy Minton and Tristan Brightman set out to test whether traditional barriers stopped larger cars such as sports utility vehicles (SUV) and multi-purpose vehicles (MPVs) from crossing the central reservation in a crash.

Sports utility vehicles

Barriers are designed to deflect vehicles back onto the road and prevent them from crossing into the opposite carriageway.

‘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 barriers,’ the authors wrote.

‘These are tested to withstand an impact with a 1,500 kilogram standard car only.

‘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.

‘However, the increase in rollover incidence and in injury severity are found to affect SUVs and MPVs to a much greater extent than standard cars.’

'Chelsea Tractors'

National road accident statistics show that 'Chelsea Tractors' are generally safer vehicles because in crashes occupants suffer less severe injuries than those in cars.

Analysing their research, Minton and Brightman wrote: ‘Occupants of SUVs and MPVs are significantly less likely to be killed or seriously injured and more likely to be uninjured compared to car occupants.’

The authors said the number of 4x4s and larger MPVs on Britain's roads had doubled in the past 15 years.

They noted that 4x4s ‘typically have a larger mass and higher centre of gravity than standard cars and hence may behave in a different way from a standard car when striking a vehicle restraint.’

They also found that 4x4s were prone to become uncontrollable at speed even before hitting a barrier.

The authors concluded that 'Chelsea Tractors' were ‘significantly more likely to overturn during an accident than are cars.’

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