A car that can anticipate a side-on impact and subtly alter its body shape to absorb the force of the crash is being developed by researchers in Germany.

The car will use hood-mounted cameras and radar to spot a vehicle on course for a side-on collision. Once it realises an impact is imminent it will activate a shape-shifting metal in the door. This reinforces the bond between door and frame, which is normally a weak spot, and distributes the force of the blow more safely.

Side impacts are as common as front or rear ones but cause many more injuries, says Joachim Tandler, a car safety researcher at engineering firm Siemens who is working on the EU-funded project.

"It's because there is so little crush zone, and less energy is absorbed before the passenger compartment is crushed," he told New Scientist. There is also insufficient time for a conventional safety system – such as a built-in airbag – to react and protect a passenger, he says.

Impact velocity
Tandler's team is working on a solution that will help protect those inside a car even before it is struck. The researchers have begun testing the impact-sensing system on experimental vehicles and have built prototypes of the shape-changing, frame-reinforcing system. "Starting next year we will have a fully integrated system on a car," he says. "In 2008 we will start full crash tests."

The experimental vehicles have radar sensors installed at the front and rear and stereo cameras in the back window. These feed information to an on-board computer that calculates the chances of an impact. "It can recognise if something is going to hit the car, identify where it will hit and its velocity," Tandler says.

To protect those inside the car, the computer would then activate a shape-memory alloy in the side door by feeding an electrical current through it. The alloy changes shape in response to heat and swells to make a stronger connection with the car's frame. The energy of the impact is then spread more widely around the car, and the risk to anyone inside is reduced. "This could make a big difference to anyone inside the car," Tandler says.