Explanation

"Always carry an advance warning triangle, or other permitted warning device, in your vehicle. Use it to warn other road users if your vehicle has broken down or there's been an incident. You're advised to place it about 45 metres (147 feet) behind the vehicle, on the same side of the road. You may need to place it further back if the vehicle is hidden by, for example, a bend, hill or dip in the road. Never attempt to place any warning device on a motorway."