A shortage of charging points and strain on energy supplies are now the main stumbling blocks to the rise of driverless electric cars, according to the UK boss of insurer Axa. Amanda Blanc said a lack of rapid charging bays and pressure on the National Grid have overtaken questions about accident liability as the biggest barriers to autonomous vehicles entering the transport mainstream. Blanc, a Tesla driver, said personal experience pointed to problems lying ahead for driverless electric vehicles. There are around 125,000 plug-in electric cars in the UK and 14,000 chargers - 2,620 of them being rapid chargers that can give a car an 80% charge in 30 minutes. Shell has just opened its first charging points for electric vehicles at 10 filling stations, mostly in London and the south-east.