Volvo softens the blow for pedestrians

Already renowned for being far ahead of the competition in safety features, Volvo again takes first place with a pedestrian airbag that will feature in its new V40.

In China, a quarter of traffic fatalities are pedestrians. In Europe, the figure is 14 per cent and in the USA 12 per cent. Far greater numbers of pedestrians are injured.

The most serious head injuries involving pedestrians and cars are caused by the hard structure under the bonnet panel, the windscreen's lower edge and the A-pillars.

These were some of the considerations when Volvo started developing its Pedestrian Airbag Technology. Seven sensors embedded in the front of the car transmit signals to a control unit. When the car makes contact with an object, the signals change. The control unit evaluates the signals and, if it registers what it interprets as a human leg, the pedestrian airbag is deployed.

The bonnet hinges are each equipped with pyrotechnical releases which, when the system is activated, pull out a pin and release the rear of the bonnet panel. At the same time, the airbag is activated and starts filling with gas. During the inflation sequence the airbag raises the bonnet. It is lifted 10cm and stays in the raised position.

The added gap between the bonnet and hard components in the engine compartment gives space for the bonnet to deform, creating a dampening effect when it is hit by a pedestrian.

"The airbag has two functions. Firstly, it raises the bonnet to create distance and, secondly, it cushions the impact around the hard parts of the area near the windscreen," explains Thomas Broberg, Volvo's senior technical adviser safety.

In its inflated position, the airbag covers the entire windscreen wiper recess, about one third of the windscreen, and the lower part of the A-pillars. The entire sequence from activation of the system to full inflation takes a few hundredths of a second.

The system is active at speeds between 20 and 50km/h - 75 per cent of all accidents involving pedestrians occur at up to 40km/h.

In 2010, Volvo launched Pedestrian Detection with full auto brake. The system can avoid a collision with a pedestrian at speeds of up to 35km/h if the driver does not respond in time.

At higher speeds the focus is on reducing that speed as much as possible before the collision.