Police are warning drivers to beware of ice after two crashes within an hour of each other on the same road.
Police were called to Wingrave Road, Tring just after 8.10am on Monday after a red Seat Ibiza slid into a ditch. The elderly male driver was not injured.
They were called back to the same area just after 8.50am when reports came in that a blue Chrysler Cruiser had crashed and flipped onto its side.
Police spokesman Sarah Spence said it was unclear what the car had crashed into, but that it was blocking the road.
Police closed the hiway while waiting for the vehicle to be recovered.