Someone struck by a large sports utility vehicle is more than twice as likely to die as someone hit by a saloon car travelling at the same speed. The finding by American researchers will add further weight to calls for SUVs ­ sporty vehicles with a high, blunt-fronted body atop a broad chassis ­ to be made safer.

In March, Jeffrey Runge, the head of the US National Highway Traffic Safety Administration (NHTSA), called on the automobile industry to make SUVs safer (New Scientist print edition, 8 March).

Their high centre of gravity makes them more likely to roll over. According to the NHTSA, 36 per cent of fatal SUV crashes in the US in 1998 involved a rollover, compared with only 15 per cent in cars.

Pedestrian fatalities

Now, by putting numbers to the risk pedestrians face from SUVs, research published in the journal Accident Analysis and Prevention (vol 36, p 295) will place more pressure on the makers to act. “This paper is very valuable in putting statistics on the risk from SUVs,” says Matthew Avery of the crash lab at Thatcham, a motor insurance industry research centre in Berkshire, UK.


Forgotten crash victims

The proportion of SUVs on the roads is increasing in both the US and Europe. Half the passenger vehicles being sold each year in the US are now classed as light trucks and vans (LTVs), a class that includes SUVs, pickups and light freight vehicles.

But no one has ever performed a broad analysis of the risk the burgeoning LTV fleet poses to people on the sidewalks, says Clay Gabler, a mechanical engineer specialising in vehicle technology at Rowan University in Glassboro, New Jersey. “In the US, pedestrians are the forgotten crash victims,” he says.

So with colleague Devon Lefler, Gabler set out to investigate risk to pedestrians from various types of LTV design. From four accident databases in the US they extracted information about accidents where one vehicle collided with one pedestrian. “LTVs are heavier, stiffer and geometrically more blunt than passenger cars and pose a dramatically different type of threat to pedestrians,” says Gabler.

The pair looked at which LTVs posed the most threat (see graph). They found that all LTVs have a higher risk of injuring pedestrians in an impact than cars. A pedestrian struck by a large van is three times as likely to die as someone hit by a car at the same speed. Pedestrians struck by large SUVs are twice as likely to die.

“The probability of serious head and thoracic injury is substantially greater than with a car,” says Gabler. As they are lower in profile, cars tend to cause leg injuries, which are less likely to kill than head injuries.

Radical design changes

Making SUVs less dangerous to pedestrians will require radical changes to their design. “One way to reduce head injuries from SUV impacts would be to replace the blunt front end with a sloping, more aerodynamic one, making them more car-like. But this won’t be popular with SUV buyers who like their rugged, off-road look,” Gabler says.

Meanwhile motor industry research is focused on making impacts between cars and SUVs safer, says Michael Cammisa of the Association of International Automobile Manufacturers, in Arlington, Virginia.

The UK Department of Transport says new rules coming into force in Europe in October 2005 will force makers of “cars and car-derived vans” to meet strict new pedestrian protection standards. “They will have to use new materials to soften up some of the areas around the bonnet so they deform controllably in an impact,” says a DoT spokesperson.

But in the US, pedestrians are losing the safety battle. “Despite over 4000 pedestrian deaths a year, there are no pedestrian impact safety regulations under serious consideration in the US,” Gabler says.