London Orbital motorway

M25
Route information
Part of E15 E30
Length:	117 mi (188 km)
Existed:	1975 – present
History:	Completed 1975–86
Major junctions
Orbital around London
	J3 → M20 motorway J5 → M26 motorway J7 → M23 motorway Junction 8 J12 → M3 motorway Junction 2 J15 → M4 motorway Junction 4B J16 → M40 motorway Junction 1A J21 → M1 motorway Junction 6A J23 → A1(M) motorway Junction 1 J27 → M11 motorway Junction 6
Location
Primary destinations:	London, Dartford, Sevenoaks, Reigate, Leatherhead, Staines, Heathrow , Rickmansworth, Watford, St Albans, Barnet, Enfield, Loughton, Brentwood, Romford, Thurrock
Road network
Roads in the United Kingdom Motorways A and B road zones

The M25 or London Orbital Motorway is a 117-mile (188 km) motorway that encircles almost all of Greater London, England (with the exception of North Ockendon), in the United Kingdom. An ambitious concept to build four concentric ring roads around London was first mooted in the 1960s. A few sections of the outer two rings were constructed in the early 1970s, but the plan was abandoned and the sections were later integrated to form a single ring which became the M25 and was finally completed in 1986.

It is one of the busiest of the British motorway network: 196,000 vehicles were recorded on a busy day near Heathrow Airport in 2003 and the western half experienced an average daily flow of 147,000 vehicles in 2007.

The M25, plus the short non-motorway A282 which joins the two ends of the M25 across the River Thames using the Dartford Crossing, is Europe's second longest orbital road after the Berliner Ring, which is 122 miles (196 km).

Originally built almost wholly as a dual three-lane motorway, much of the motorway has been widened: to dual four lanes for almost half, to a dual five-lanes section between junctions 12 and 14 and a dual six-lane section between junctions 14 and 15. Further widening is in progress of minor sections with plans for managed motorways in many others.

To the east of London the two ends of the M25 are joined to complete a loop by the non-motorway A282 Dartford Crossing of the River Thames between Thurrock and Dartford. This crossing, which consists of twin two-lane tunnels and the four-lane QE2 (Queen Elizabeth II) bridge, is named Canterbury Way. Passage across the bridge or through the tunnels is subject to a toll, its level depending on the kind of vehicle. This stretch being non-motorway allows traffic, including that not permitted to use motorways, to cross the River Thames east of the Woolwich Ferry; the only crossing further to the east is a passenger ferry between Gravesend, in Kent, and Tilbury, in Essex.

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Wikipedia