IN AN average month 108,000 people are killed in traffic accidents around the world, and the death toll is increasing. On current trends it will exceed 150,000 people a month by 2020, according to the World Health Organisation, as cars become more widespread in developing countries, increasing the number of vehicles on the world’s roads from around 1 billion in 2010 to 2 billion. Many lives will be spared by outfitting more vehicles with airbags, the biggest lifesavers in car technology since seat belts. But now a far greater revolution in road safety is within reach. Around 90% of accidents are caused by human error. Design vehicles so that they can drive themselves, goes the theory, and death tolls will plummet.