M25 motorway the east of Gravesend and Grays, the Lower Thames Crossing, in order to relieve congestion on the A282 Dartford Crossing and connect the M25 at North Ockendon in Essex with the M2 in Kent. At Junction 5, the clockwise carriageway of the M25 is routed off the main north–south dual carriageway onto the main east–west dual carriageway with the main north–south carriageway becoming the A21. In the opposite direction, to the east of the point where the M25 diverges from the main east–west carriageway, that carriageway become the M26 motorway. The radial distance from London (taken as Charing Cross) varies
M25 motorway this time depicting these short sections named the route as the M16 but this changed before completion. The section from Potters Bar to the Dartford Tunnel was constructed between 1979 and 1982. Construction of the M25 continued in stages until its completion in 1986. Prime Minister Margaret Thatcher officially opened the M25 on 29 October 1986, with a ceremony in the section between J22 and J23 (London Colney and South Mimms). The initial tenders for the construction of the M25 totalled £631.9 million. This did not include compulsory purchase of land and subsequent upgrades and repairs. Soon after the motorway