Driver Knowledge Tests

Will self-driving cars ever mean that road deaths will reduce to zero?

Self-driving vehicles could reduce road fatalities to close to zero but it would require all vehicles to be self-driving (including motorbikes, which is unlikely) and for a complete separation of pedestrian and vehicular traffic.

Cyclists and pedestrians are included in road fatality statistics and it would be impossible to eliminate every scenario where they are killed or injured. For example, if a distracted pedestrian steps out in front of a bus, if there is insufficient space for the bus to stop or manoeuvre around the pedestrian, the pedestrian will be struck by the bus, regardless of whether a computer was in control. The risk of this happening will be reduced – the bus might react earlier – but not eliminated.

Cyclists also die in single-vehicle accidents, although this is not common.

There are other scenarios where basic laws of physics would mean that while it’s possible to minimise the impact of an accident, it’s not possible to eliminate it. For example, a landslide wipes out a vehicle, a large animal jumps in front of a vehicle and comes through the windscreen (e.g. moose in North America, kangaroo in Australia, etc).

Mechanical failures

A small number of crashes are attributed to mechanical failures. According to motorcycle crashes analysed by Monash University, mechanical faults contributed to around 12% of crashes overall, but this comprised 28% of single-vehicle crashes and 7% of multi-vehicle crashes. On a motorbike, the potential causes of crashes were puncture, broken chain and brake failure. Punctures on cars and trucks are less likely to result in a loss of control


Then we come to motorbikes: the appeal of a motorbike is that you are ‘at one with the machine and nature’. There are inherent issues with self-driving motorbikes, the main one being that the rider uses their weight to steer the bike, rather than it being something that can be mechanically controlled like a car or truck. However, BMW has created an autonomous motorcycle, but it is riding without a rider. The issue would be the rider staying on the machine while the machine is in control, given that the rider isn’t contained within the vehicle like with a car or truck.

Classic cars

Classic cars are a hobby for many. Part of the appeal is the lack of driver aids found in modern cars. Short of retrofitting autonomous driving systems, they will always require human drivers.


While having a vision of zero road deaths is noble, it’s not a vision, it’s a fantasy. The reality is that when a heavy object is moving in a particular direction and a human is in control of it, human error will always play some role in its safety. If human error is eliminated, mechanical error may still cause deaths. If mechanical errors are mitigated, natural events will still cause fatalities.

Every system has a built-in tolerance for deaths, whether it’s air travel, alcohol consumption, smoking or driving; we could easily eliminate all related deaths simply by stopping each one of them. However, that’s not practical. The opportunity is to address the challenges with meaningful goals. Self-driving cars will undoubtedly reduce road deaths, but they won’t eliminate them.

Darren is an expert on driving and transport, and is a member of the Institute of Advanced Motorists

Posted in Advice