which is the inside lane on a road
Overtaking Overtaking on the inside or undertaking[2][3][4] refers to the practice of overtaking a slower vehicle on a road using the lane that is kerb side of the vehicle being passed; that is to say, a lane to the left of the vehicle in countries where driving is on the left, or a lane to the right of the vehicle in countries where driving is on the right. The practice of passing on the inside, therefore, usually only occurs on a motorway or other road where there is more than one lane in the same direction or when the width of the roads makes this possible (although there may be exceptions in the cases of contraflow bus lanes).