M25 motorway

2007 Schools Wikipedia Selection. Related subjects: Geography of Great Britain; Road transport

M25 motorway
Length 117 miles
188 km
Direction Circular
Start Dartford
Primary destinations London
Gatwick Airport
Heathrow Airport
Hemel Hempstead
Stansted Airport
End West Thurrock
Construction dates 1975 - 1986
Motorways joined 3 -
M20 motorway
5 -
M26 motorway
7 -
M23 motorway
12 -
M3 motorway
15 -
M4 motorway
16 -
M40 motorway
21 -
M1 motorway
23 -
A1(M) motorway
27 -
M11 motorway
The M25 motorway looking south between junctions 14 and 15, near Heathrow Airport. The red light from the overhead gantry, just visible in the distance, is the MIDAS system indicating a reduced speed limit due to congestion
The M25 motorway looking south between junctions 14 and 15, near Heathrow Airport. The red light from the overhead gantry, just visible in the distance, is the MIDAS system indicating a reduced speed limit due to congestion
The M25 between junction 24 (Potters Bar) and 25 (Waltham Cross).
The M25 between junction 24 ( Potters Bar) and 25 (Waltham Cross).

The M25 motorway is one of the United Kingdom's motorways. It is an orbital motorway, 117 miles (188 km) in circumference, that almost completely encircles London (the gap is formed in the east, with the Dartford Crossing or the A282, linking two sides of the River Thames). It is said to be one of the longest city bypasses in the world. In Europe the M25 is the second-longest ring road after the Berlin Ring ( A 10).


For most of its length the motorway has six lanes (three in each direction), although there are a few short stretches which are four-lane and perhaps one sixth is eight-lane, around the south-western corner. The motorway was widened to ten lanes between junctions 12 and 14, and twelve lanes between junctions 14 and 15, in November 2005. The Highways Agency has plans to widen almost all of the remaining stretches of the M25 to eight lanes.

It is one of Europe's busiest motorways, with 196,000 vehicles a day recorded in 2003 between junctions 13 and 14 near London Heathrow Airport ( ), significantly less, however, than the 257,000 vehicles a day recorded in 2002 on the A4 motorway at Saint-Maurice, in the suburbs of Paris ( ), or the 216,000 vehicles a day recorded in 1998 on the A 100 motorway near the Funkturm in Berlin ( ).

The M25 is not a continuous loop. To the east of London, the toll crossing of the Thames between Thurrock and Dartford is the non-motorway A282. The Dartford Crossing, which consists of two tunnels and the QE2 (Queen Elizabeth II) bridge, is named Canterbury Way. Passage across the bridge or through the tunnels is subject to a toll, dependent upon the type of vehicle. Designating this stretch as a motorway would mean that traffic not permitted to use motorways could not cross the Thames east of Woolwich.

While this is more a structural than a logical issue, at junction 5 near Sevenoaks continuing around the M25 requires the driver to follow the slip roads, as the anticlockwise carriageway continues as the M26 to the east (towards the M20) and the clockwise as the A21 towards the south coast.

The road passes through multiple police force areas. Junctions 1–5 are in Kent, 6–14 in Surrey (passing at places through Greater London and Berkshire), 15–16 are in Buckinghamshire, 17–24 are in Hertfordshire, 25 in Greater London, 26–28 in Essex, 29 in Greater London and 30–31 in Essex. Policing the road is carried out by an integrated policing group made up of the Metropolitan, Thames Valley, Essex, Kent, Hertfordshire and Surrey forces.

The distance of the motorway from central London (taken as Charing Cross) varies from approximately 12 miles (20 km) near Potters Bar to 20 miles (32 km) near Byfleet. In some places (Enfield, Hillingdon and Havering) the Greater London boundary has been aligned to the M25 while in others, most notably in Surrey, it is many miles distant. North Ockendon is the only settlement of Greater London to be outside the M25. In 2004, following a poll, a move was mooted by the London Assembly to entirely align the Greater London boundary to the M25.


The idea of an orbital road around London was first proposed early in the 20th century and was re-examined a number of times during the first half of the 20th century inclunding in Sir Edwin Lutyens and Sir Charles Bressey's The Highway Development Survey, 1937 smd Sir Patrick Abercrombie's County of London Plan, 1943 and Greater London Plan, 1944. Abercrombie's plan proposed a series of five roads ringing the capital.

In the post-war years little was done to implement Abercrombie's plans but in the 1960s the Greater London Council developed an ambitious plan for a network of ring roads around the capital. The London Ringways plan was hugely controversial due to the destruction required for the inner two ring roads and the enormous anticipated cost. The plan was modified a number of times to overcome opposition from the residents of threatened areas and the government, but was cancelled in 1973. Parts of the two outer ring roads, Ringways 3 and 4, were begun in 1973 and became the first two sections of the M25 to open in 1975 (junction1 23 to junction 24) and 1976 (junction 6 to junction 8).

Construction of the M25 continued in stages until its completion in 1986. The stages were not constructed contiguously but in small sections, such as Dartford to Swanley (junction 1 to junction 3) and Potters Bar to Waltham Cross (junction 24 to junction J25). As the orbital road developed the sections were linked. Each section was presented to planning authorities in its own right and was individually justified; there were almost 40 public inquiries relating to sections of the route. Maps at this time depicting these short sections named the route as the M16 but this changed prior to completion. The north sections of the M25 follow a similar route to the World War II Outer London Defence Ring.

The M25 was officially opened on October 29, 1986 with a ceremony by Prime Minister Margaret Thatcher opening 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.

More recently, the perennially congested south-western stretch of the M25 (near Woking) has been fitted with an experimental automated traffic control system called Motorway Incident Detection and Automatic Signalling (MIDAS). This consists of a distributed network of traffic and weather sensors, speed cameras and variable-speed signs that control traffic speeds with little human supervision. The system has reduced congestion and it is hoped that MIDAS will be fitted to the rest of the M25 in due course.

A precursor of the M25 was the North Orbital Road.

Illuminated sections

Large sections of the M25 are illuminated with the aim of reducing accidents on the road. The current illuminated sections are Dartford to junction 2, junction 5, junctions 6 to 16, junctions 18 to 21A, and junctions 23 to 31. It is thought that when the widening of the M25 is completed junctions 3 to 5 will be the only area unlit, as this is the quietest part of the M25. The type of lights on the M25 varies, with some of the sections using the older yellow low pressure Sodium (SOX) lighting, and others with modern high pressure Sodium (SON) lighting.


The multi level junction with the M23.
The multi level junction with the M23.
M25 Motorway
Anticlockwise exits Junction Clockwise exits
Erith A206 J1a Swanscombe A206
Dartford A225 J1b No Exit
London, Canterbury A2, ( M2)
Dartford (A225)
J2 London, Canterbury A2, (M2)
London (South East) A20
Maidstone M20
Swanley B2173
J3 Maidstone, Channel Tunnel, Dover M20
London (South East), Swanley A20
Bromley A21
Orpington A224
J4 Bromley A21
Orpington A224
Maidstone, Channel Tunnel, Dover M26 (M20)
Sevenoaks, Hastings A21
J5 Sevenoaks, Hastings A21
Clacket Lane services
East Grinstead, Eastbourne, Caterham, Godstone A22
Westerham ( A25)
J6 East Grinstead, Eastbourne, Caterham, Godstone, A22
Redhill (A25)
Gatwick Airport, Crawley, Brighton, East Grinstead, Croydon M23 J7 Gatwick Airport, Crawley, Brighton, Croydon M23
Reigate, Sutton A217
Redhill (A25)
J8 Reigate, Sutton A217
Kingston ( A240)
Leatherhead A243
Dorking ( A24)
J9 Leatherhead A243
Dorking (A24)
London (South West), Kingston, Guildford A3 J10 London (South West), Guildford A3
Chertsey A317
Woking A320
J11 Woking A320
Chertsey A317
Basingstoke, Southampton, Sunbury M3 J12 Basingstoke, Southampton, Sunbury M3
Staines A30 J13 London (West), Staines A30
Heathrow Airport (Terminals 4, 5 and Cargo) A3113 J14 Heathrow Airport (Terminals 4, 5 and Cargo) A3113
The WEST, Slough, Reading, London (West), Heathrow Airport (Terminals 1, 2 and 3) M4 J15 The WEST, Slough, Reading, London (West), Heathrow Airport (Terminals 1 2, and 3) M4
Birmingham, Oxford, Uxbridge, London (West) M40 J16 Birmingham, Oxford, Uxbridge, London (West) M40
Maple Cross ( A412) J17 Maple Cross, Rickmansworth (A412)
Rickmansworth, Chorleywood, Amersham A404 J18 Chorleywood, Amersham A404
No Exit J19 Watford A41
Hemel Hempstead, Aylesbury A41 J20 Hemel Hempstead, Aylesbury A41
The NORTH, Luton & Airport M1 J21 The NORTH, Luton & Airport M1
Watford A405
Harrow (M1 South)
J21A St. Albans A405
London (North West) (M1 (South))
St. Albans A1081 J22 St. Albans A1081
Hatfield A1(M)
London (North West) A1
Barnet A1081
South Mimms services
J23 Hatfield A1(M)
London (North West) A1
Barnet A1081
South Mimms services
Potters Bar A111 J24 Potters Bar A111
Enfield, Hertford A10 J25 Enfield, Hertford A10
Waltham Abbey, Loughton A121 J26 Waltham Abbey, Loughton A121
London (North East), Stansted Airport, Harlow, Cambridge M11 J27 London (North East), Stansted Airport, Harlow, Cambridge M11
Chelmsford, Witham, Colchester A12
Brentwood A1203
J28 Chelmsford, Romford A12
Brentwood A1023
Romford, Basildon, Southend A127 J29 Basildon, Southend A127
Thurrock ( Lakeside), Tilbury A13
Thurrock services
J30 Dagenham, Thurrock (Lakeside), Tilbury A13, ( A1306, A126, A1090)
Thurrock services
South Ockendon, Dagenham A1306 J31 No Exit


The M25 (including the A282 Dartford Crossing) is known for its frequent jams. These have been the subject of so much comment from such an early stage that even at the official opening ceremony Margaret Thatcher complained about "those who carp and criticise". The jams have inspired jokes ("the world's biggest car park"), songs ( Chris Rea's "The Road to Hell") and the following tongue-in-cheek theory:

"Many phenomena — wars, plagues, sudden audits — have been advanced as evidence for the hidden hand of Satan in the affairs of Man, but whenever students of demonology get together the M25 London orbital motorway is generally agreed to be among the top contenders for exhibit A."
— from Good Omens, by Terry Pratchett and Neil Gaiman.

The M25's name inspired the name of the electronica duo, Orbital.

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