Transformers: Protecting Pedestrians From Killer Cars

April 18, 2009— -- Pity the poor pedestrian.

While vehicle drivers and their passengers are cocooned in a crash, people hit by a car have no such protection. Now that could change, thanks to a variety of systems that when built into a vehicle will improve a pedestrian's chances.

Every month approximately 3400 people are killed in traffic accidents on the roads in the US, and a similar number die in Europe. Some 30 per cent of the injuries sustained by this group are caused by an impact with a windscreen or its frame.

A Europe-wide collaboration led by Roger Hardy of the Cranfield Impact Centre at Cranfield University near Bedford in the UK has developed an experimental system for cars that aims to cut this death toll and reduce the severity of injuries.

When the system detects that the car is about to hit a pedestrian, it automatically raises the rear of the bonnet (hood), releasing a giant airbag in front of the windscreen.

The raised bonnet absorbs some of the energy of the impact, reducing the risk of serious injury to the pedestrian, says Hardy, whose project forms part of the European Union-funded Integrated Project on Advanced Protection Systems (APROSYS).

"If it's a large pedestrian or on a small town car, the airbag also provides a cushioning effect around the stiff peripheral regions [of the windscreen]," he says.

The airbag system used by Hardy was developed by the German company Takata Petri. To test its efficacy when combined with the raised bonnet, they were incorporated into a prototype Fiat Stilo by engineers at the Fiat Research Centre in Turin, Italy. The team then assessed the severity of head injuries in collisions with a dummy pedestrian.

A standard Stilo hitting a pedestrian at 40 kilometres per hour, so that their heads struck the back of the bonnet, would have a score of around 1000 on the Head Impact Criterion (HIC) scale - corresponding to an 18 per cent chance of a life-threatening injury.

For pedestrians hitting Hardy's bonnet, the scores were reduced to between 234 and 682, while the windscreen airbag scores ranged from 692 to 945.