When you take a human driver out of the equation, self-driving cars suddenly have complete responsibility for the safety of all users on the road. That includes pedestrians, which is why the AI fork of the trolley problem is so fascinating.

In those moments where a collision with a human is inevitable, is there anything else the manufacturers of driverless cars can do to help prevent the loss of human life? Waymo, the autonomous car company that includes Google among its Alphabet-owned stablemates, is looking into revolutionary design ideas to tackle the problem.

In a newly-uncovered patent from 2015, it describes a system that would see its vehicles 'soften' ahead of an identified imminent impact with a pedestrian.

Weighing up the safety options

The system would use a collection of springs and cables to reduce the rigidity of bumpers and panels, should the vehicle's computer system spot a potential collision about to occur. The theory behind the patent suggests this would be a safer surface for the human to hit at speed.

However, what does this mean for the safety of the passengers of the vehicle? In the event of a crash, the integrity of the body of the car is essential to protecting passengers. Waymo's idea would seem to go against years of accepted knowledge around crumple zones and the like.

But it's interesting to see Waymo considering safety from all angles, especially beyond the AI ethical concerns.