The Dartford Tunnel crossed the River Thames between Dartford, Kent and Thurrock, Essex, facilitating northbound traffic. They were built between 1936 and 1980 and classed as one of the most significant river crossings in Britain and indeed Europe. The crossing comprises of 2 tunnels and the Queen Elizabeth II Bridge.
Originally the crossing was a single carriage tunnel and was called Dartford Tunnel until the opening of QEII Bridge. Plans for the tunnel started in the 1920s with a hole being constructed in 1936 and consequently boring works in 1938. Work was halted due to the 2nd World War and did not resume until 1955.
It was planned to connect to the North Orbital and South Orbital roads but the road had not been fixed to the south of the crossing there was no choice but to halt the approach road on the A2 which was then heavily congested. Kent County Council and The Ministry of Transport argued over the arrangements, which were not eventually agreed until 1963. The tunnel then opened to traffic in November.
The tunnel was immediate success although only single carriageway at the time as it was built to a much higher standard than any other Thames crossing east of Tower Bridge, and soon became the main crossing point across the river in the area. By 1970 there was pressing demand to create a second tunnel to offer a full double carriageway link-up with Ringway 3 and the Dartford Bypass. Construction began on the secondary tunnel in 1971 with a planned opening date of 1976. This project was also delayed due to objections at the public enquiry, and eventually opened in 1980.
At this time, the M25 had been planned, and road sections were either open or under construction. The section south of Swanley resulted in a huge increase in traffic so a third crossing was planned in 1987 which became the Queen Elizabeth II Bridge, (also referred to as the Dartford Bridge) which opened in October 1991.
There has been a toll on the crossing since it was opened. Repayments were completed in 2003 and there was a call for the toll charges to be stopped. The tolls then became part-time and from 2012 it has been free for motorcycles, £2 for cars, £2.50 for 2 axle goods vehicles and £5.00 for multi axle goods vehicles. There are no charges between the hours of 10pm and 6am.
As well as human toll collection, an electronic tag system called DART-Tag was also used and gave a discounted rate of £1 for cars, £1.75 for 2 axle vehicles and £3.20 for multi-axle vehicles.