An idea of a tunnel crossing was proposed by the Ministry of Transport in 1924. Initial reports suggested a crossing between Tilbury and Gravesend, but this was rejected in favour of a route further upstream, near Dartford. By 1929, the total cost of building the tunnel was estimated at £3 million. The tunnel was planned to be part of a general orbital route around London and was provisionally known as part of the ’South Orbital Road’.
The first engineering work to take place was a compressed air driven pilot tunnel, drilled between 1936 and 1938. Work on the tunnel was delayed due to World War II, and resumed in 1959. The two-lane tunnel opened to traffic on 18 November 1963 with the total project being £13 million. It initially served approximately 12 000 vehicles per day.
