The first engineering work to take place was a compressed air driven pilot tunnel, which was drilled between 1936 and 1938. Work on the tunnel was delayed due to World War II, and resumed in 1959, using a Greathead Shield, similar to the work on the Blackwall Tunnel some 60 years earlier. The delay in work due to the war allowed the tunnel's design to be improved, which included a better ventilation system. After negotiations with the Ministry of Transport, Kent and Essex County Councils obtained government approval to charge tolls in 1960, before opening. The two-lane bore tunnel opened to traffic on 18 November 1963; the total project cost was £13 million (equivalent to £ million in ) and it initially served approximately 12,000 vehicles per day.