When the system detects an accident, it deploys the bridge bar in 70 milliseconds using a high-power spring, which is being held by a coil. The coil is made of an special alloy that recovers its original shape instantly when it receives an electric impulse, releasing the spring just before the impact. The resulting structure decreases the penetration of the incoming object by as much as 3 inches, as well as reducing the speed and violence of the crash.
Side impacts are almost impossible to avoid even at very low speeds, like 20-30 mph. They are also very dangerous, not only because they can kill you straight away, but also because it's very easy to suffer permanent brain damage from the lateral forces involved. The system may avoid this, transferring these energies through the car structure. [New Scientist]