The Dartford-Thurrock River Crossing, commonly known as the Dartford Crossing and until 1991 the Dartford Tunnel, is a major road crossing of the River Thames in England, connecting Dartford in Kent to the south to Thurrock in Essex to the north. It consists of two bored tunnels and the Queen Elizabeth II Bridge, a cable stayed bridge. The only fixed road crossing of the Thames east of Greater London, it is the busiest estuarial crossing in the United Kingdom, with an average daily use of over 130,000 vehicles. It opened in stages: the west tunnel in 1963, the east tunnel in 1980 and the bridge in 1991. The crossing forms part of the M25 motorway's route, though it is not under motorway restrictions itself. It has been described as one of the most important road crossings in Britain, and suffers from heavy traffic and congestion.