M25 motorway

circular motorway outlining most of London
(Redirected from M25)

The M25 motorway, or London Orbital, is a 117-mile (188 km) orbital motorway around Greater London.

M25 shield
London Orbital Motorway
Egham M25 aerial 2011.jpg
Junction 13 looking south
Route information
Part of E15 and E30[1]
Maintained by Connect Plus (contracted to Highways England)
Length117 mi (188 km)
HistoryOpened: 1975
Completed: 1986
Major junctions
Orbital around London (along with the A282)
South endDartford (Dartford Crossing southern approach)
Major intersections
J3 → M20 motorway

J5 → M26 motorway

J7 → M23 motorway

J12 → M3 motorway

J15 → M4 motorway

J16 → M40 motorway

J21 → M1 motorway

J23 → A1(M) motorway

J27 → M11 motorway
North endThurrock (Dartford Crossing northern approach)
CountryUnited Kingdom
CountiesKent, Surrey, Berkshire, Greater London, Buckinghamshire, Hertfordshire, Essex
Dartford Crossing
Gatwick Airport
Heathrow Airport
Stansted Airport
Road network
Number of lanes as of 2009

The motorway was first suggested early in the 20th century, and a few sections were built in the early 1970s. The M25 was completed in 1986: is one of the world's longest orbital roads.[2]

It is one of the busiest and most congested parts of the British motorway network. 196,000 vehicles were recorded in a single day near London Heathrow Airport. The M25 is a crucial link between the four main London airports: Heathrow, Gatwick, Stansted and Luton.

Bearing in mind that no motorways go through the centre of London, the M25 is a main route connecting north with south, and east with the west of England.

The motorway was originally built with only six lanes (three each way), despite research which suggested eight lanes were necessary. Now a fourth lane exists over most of the motorway, and more in special sections (see diagram). Plans were scaled back in 2009 in response to rising costs, but work is still going on.[3]



Public enquiries continued through the 1970s and 1980s. Each section had its own enquiry, where local citizens and interest groups could question the plans. In all, "39 public inquiries before independent Inspectors were held, taking over 700 sitting days – with many more working days (and nights) preparing evidence".[4] Objectors could put forward alternatives, and each of these had to be answered with presentation of evidence. Evidence included predictions of traffic and events which would affect growth of traffic. Enquiries and evidence were open to public scrutiny and debate.

Some enquiries lasted a day, and one one lasted 97 sitting days over 13 months.[4] Proposals had to go before Parliament, and a special Act was needed to authorise the crossing of the northern tip of Epping Forest by the route in tunnel.

Operational history


As predicted by research, soon after the motorway opened in 1986 traffic levels exceeded maximum designed capacity. In 1990 the Secretary of State for Transport announced plans to widen the whole of the M25 to four lanes.[5] By 1993 the motorway that was designed for a maximum of 88,000 vehicles per day was carrying 200,000.[6] 15% of UK motorway traffic volume was on the M25 and there were plans to add 6 lanes to the section from Junction 12 to 15 as well widening the rest of the motorway to 4 lanes.[7]

In 1995 a contract was awarded to widen the section between junctions 8 and 10 from six to eight lanes for a cost of £93.4 million[8] and a 'Motorway Incident Detection and Automatic Signalling' (MIDAS) system was introduced to the M25 from junction 10 to junction 15 at a cost of £13.5m in 1995 and then extended to junction 16 at a cost of £11.7m in 2002. 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 improved traffic flow slightly, and reduced the amount of start-stop driving.[9] The use of variable speed limits makes this a "controlled motorway", and if hard shoulders are used at peak times it becomes a "managed motorway".

In 1995 there was a proposal to widen the section close to Heathrow Airport to 14 lanes. This attracted fierce opposition from road protesters opposing the Newbury Bypass and other schemes,[10] and it was cancelled shortly afterwards.[11] However, in 1997 the Department of Transport announced new proposals to widen the section from junction 12 (M3) and junction 15 (M4) to 12 lanes. At the Terminal Five public inquiry a Highways Agency official said that the widening was needed to accommodate traffic to the proposed new terminal, however the transport minister said that no such evidence had been given.[12] Environmental groups objected to the decision to go ahead without holding a public inquiry.[13] A decision to go-ahead was given for a 10-lane scheme in 1998,[14] and the £148 million 'M25 Jct 12 to 15 Widening' contract was awarded to Balfour Beatty in 2003.[15] The scheme was completed in 2005 as dual-five lane between junctions 12 to 14 and dual six lanes from 14 to 15.[16]

The road cost £1 billion (in 1980s money) and took 11 years to build. It used two million tons of concrete and 3½ million tons of asphalt.[17]



Traffic bottleneck at the Dartford Crossing in the east is the greatest problem on the motorway at present, even though the crossing is technically not part of the M25. At present the crossing is by bridge from the north, and by tunnel from the south. There are usually long tailbacks in both directions.[18]



On its 25th birthday the BBC listed some of its effect on life near the capital:[17]

  • Built business empires and spread business from the capital. A new commercial property market has developed. In the M25 area there is 130 million square feet of extra commercial space. Compare this with the City of London, where the total is about 170 million square feet. The M25 is a big catchment area in terms of employment.
  • Increased house prices. Before the M25, areas just outside London were a mixture of small rural farms and commuter belt. Its arrival helped those commuters get on their way faster, pushing house prices in such areas higher. "We know from our research that house prices generally have gone up about 300% since the M25 opened in 1986," says Anthony Wardell from Knight Franks estate agents. On the western side of London, house prices have gone up nearer to 400%, he adds.
  • Changed the way people plan their lives. M25 expert Chris Marshall says "You can get around London in ways that you couldn't do before and it doesn't just change the lives of people who lived around it before, or who worked around it before, you find that actually it changes the way that people plan their lives. So now not only does someone who lived in Harlow when it was opened have the opportunity to work somewhere else, but someone say who works say in Heathrow can buy a house on the other side of London."


A282 (Dartford Crossing)
miles km[19][a] Clockwise exits (A carriageway)[19] Junction Anti-clockwise exits (B carriageway) Opening date[20]
0.0 0.0 Dartford Crossing South
(Queen Elizabeth II Bridge)
Dartford Crossing North
(Dartford Tunnels)
November 1963 (west tunnel)
May 1980 (east tunnel)
October 1991 (bridge)
3.5 5.7 Erith A206 J1A[b] Erith A206, Swanscombe (A226) September 1986
4.7 7.5 Dartford A225 J1B Exit via J2 – Dartford (A225) September 1986
5.5 8.8 London (SE & C), Bexleyheath A2 (W), Canterbury (M2) A2 (E) Ebbsfleet International, Gillingham J2 London (SE & C), Bexleyheath A2, Canterbury (M2), Dartford (A225) Ebbsfleet International, Bluewater, Gillingham
Gillingham A2
Dover, Chnl Tnl (M20)
M25(S) (M23)
Rochester A2
September 1986 (northbound)
April 1977 (southbound)
8.7 14.0 London (SE & C) A20
Maidstone, Channel Tunnel, Folkestone M20
Swanley B2173
J3 Maidstone, Channel Tunnel M20
London (SE & C), Lewisham A20
April 1977 (northbound)
February 1986 (southbound)
12.2 19.6 Bromley A21
Orpington A224
J4 Bromley, London (SE & C) A21
Orpington (A224)
February 1986
Sevenoaks, Royal Tunbridge Wells, Hastings A21 J5 Maidstone, Channel Tunnel, Dover M26 (M20)
Sevenoaks, Hastings A21
July 1980
21.0 33.8 Clacket Lane services Services Clacket Lane services July 1993
25.8 41.6 East Grinstead, Eastbourne, Caterham, Godstone A22
Redhill, Westerham (A25)
J6 East Grinstead, Eastbourne, Caterham, Godstone A22
Redhill, Westerham (A25)
November 1979 (eastbound)
February 1976 (westbound)
28.6 46.0 Gatwick Airport, Crawley, Brighton, Croydon M23 J7 Gatwick Airport, Crawley, Brighton, M23(S), Croydon M23(N) February 1976
31.9 51.4 London (S & SW), Reigate, Sutton A217
Kingston (A240)
J8 London (S & SW), Reigate, Sutton A217
Kingston (A240)
February 1976 (eastbound)
October 1985 (westbound)
Leatherhead A243, Dorking, (A24) J9 Leatherhead A243, Dorking (A24) October 1985
Cobham services Services Cobham services September 2012
45.0 72.4 London (SW & C), Guildford, Portsmouth A3 J10 London (SW & C), Guildford, Kingston A3 October 1985 (eastbound)
December 1983 (westbound)
49.8 80.2 Chertsey A317, Woking A320 J11 Woking A320, Chertsey A317 December 1983 (southbound)
October 1980 (northbound)
52.1 83.8 Basingstoke, Southampton, Richmond M3 J12 Basingstoke, Southampton, Richmond M3 October 1980 (southbound)
December 1976 (northbound)
55.2 88.8 London (W & C), Hounslow, Staines A30 J13 London (W & C), Hounslow, Staines A30 November 1981 (southbound)
August 1982 (northbound)
57.0 91.8 Heathrow Airport (Terminals 4, 5 and Cargo) A3113 J14 Heathrow Airport (Terminals 4, 5 and Cargo) A3113 August 1982 (southbound)
September 1985 (northbound)
59.0 95.0 The WEST, Slough, Reading, London (W & C), Heathrow Airport (Terminals 2 and 3) M4 J15 The WEST, Slough, Reading M4(W)
London (W & C), Heathrow Airport (Terminals 2 & 3) M4(E)
September 1985
63.8 102.6 The NORTH, Birmingham, Oxford, Uxbridge, London (W & C) M40 J16 Birmingham, Oxford M40(W)
Uxbridge, London (W & C) M40(E)
September 1985 (southbound)
January 1985 (northbound)
68.7 110.5 Rickmansworth, Maple Cross (A412) J17 Rickmansworth, Maple Cross A412 January 1985 (southbound)
February 1976 (northbound)
69.9 112.5 Chorleywood, Amersham A404 J18 Chorleywood, Amersham A404 February 1976
71.5 116.4 Watford A41 J19 Exit via J20 – Watford A41 September 1976
73.5 118.2 Hemel Hempstead, Aylesbury A41 J20 Hemel Hempstead, Aylesbury, Watford A41 August 1986
76.3 122.8 The North, Luton & Luton Airport M1 J21 The North, Luton & Luton Airport M1 August 1986
76.9 123.7 Watford A405
Harrow (M1 South)
J21A St Albans A405
London (NW & C) (M1 (South))
August 1986
80.6 129.7 London Colney A1081 J22 St Albans A1081 August 1986
83.3 134.0 Hatfield A1(M), London (NW & C) A1, Barnet A1081
South Mimms services
J23 Hatfield A1(M), London (NW & C) A1, Barnet A1081
South Mimms services
August 1986 (westbound)
September 1975 (eastbound)
85.9 138.2 Potters Bar A111 J24 Potters Bar A111 September 1975 (westbound)
June 1981 (eastbound)
91.4 147.1 Enfield Town, Hertford A10 J25 Enfield, Hertford, London (N & C) A10 June 1981 (westbound)
January 1984 (eastbound)
94.9 152.7 Waltham Abbey, Loughton A121 J26 Waltham Abbey, Loughton A121 January 1984
99.2 159.7 London (NE & C), Stansted Airport, Harlow, Cambridge M11 J27 London (NE & C) M11(N), Stansted Airport, Harlow, Cambridge M11(S) January 1984 (westbound)
April 1983 (eastbound)
107.1 172.4 Chelmsford, Witham, Colchester A12
Brentwood A1023
J28 Chelmsford, Romford A12
Brentwood A1023
April 1983
109.9 176.8 Romford, Basildon, Southend A127 J29 Basildon, Southend, Romford A127 April 1983 (northbound)
December 1982 (southbound)
115.2 185.4 Tilbury, Thurrock, Lakeside A13(E), London (E & C) A13(W)
Thurrock services
J30 London (E & C), Barking, Tilbury, Basildon, Dagenham, Rainham A13 December 1982
A282 (Dartford Crossing)
115.9 186.6 Exit via J30 – Purfleet (A1090), South Ockendon, Thurrock services A1306 J31 Thurrock (Lakeside), Thurrock services A1306, Purfleet (A1090), West Thurrock (A126) December 1982
Dartford Crossing South
(Queen Elizabeth II Bridge)
Dartford Crossing North
(Dartford Tunnels)
November 1963 (west tunnel)
May 1980 (east tunnel)
October 1991 (bridge)
  • Distances in kilometres and carriageway identifiers are taken from driver location signs/location marker posts. Where a junction goes across several hundred metres and the data is available, both the start and finish values for the junction are shown.
1.000 mi = 1.609 km; 1.000 km = 0.621 mi
  1. The table gives details of each junction, including the roads interchanged and the destinations that are signed from the motorway on the blue advance direction signs. Figures in kilometres are from the driver location signs; figures in miles are derived from them.
  2. Junctions 1A and 1B are part of the A282, though they use the M25's numbering scheme.[21]


  1. AA Publishing (2019). Big Road Atlas Europe 2020.
  2. "M25 London Orbital Motorway (Junctions 13 to 30)". The Motorway Archive. Archived from the original on 22 December 2008. Retrieved 3 January 2009.
  3. Webster, Ben (2009-06-25). "Rising costs put the brakes on dozens of roadbuilding projects". The Times. London. Retrieved 2010-05-12.
  4. 4.0 4.1 "The Motorway Archive : The M25 London Orbital Motorway". Archived from the original on 2011-07-25. Retrieved 2011-09-21.
  5. "HANSARD 3 December 1990 Written Answers (Commons) TRANSPORT". Archived from the original on 5 January 2021. Retrieved 21 September 2011.
  6. "The bluffer's briefing on: The M25". The Independent. London. 1993-03-24. Retrieved 2010-05-12.
  7. "M25 (Widening)". Hansard. Archived from the original on 2021-01-05. Retrieved 2011-09-21.
  8. "M25 scoop for Balfour in Surrey". 2 March 1995. Archived from the original on 16 October 2015. Retrieved 21 September 2011.
  9. "Case Study - M25 Controlled Motorway". Highways Agency. Archived from the original on 2012-09-26. Retrieved 2011-09-21.
  10. Wolmar, Christian (1995-04-04). "The roadblock that became a bandwagon". The Independent. London. Retrieved 2010-05-12.
  11. Cohen, Nick (1995-04-02). "Pointless lies that reveal so much". The Independent. London. Retrieved 2010-05-12.
  12. Wolmar, Christian (1997-03-21). "Minister gives green light to widen M25". The Independent. London. Archived from the original on 2012-01-21. Retrieved 2010-05-12.
  13. "Plans to widen M25 to 12 lanes under attack". 28 March 1997.
  14. "BAA makes plans for Terminal 5 despite inquiry". 6 August 1998. Archived from the original on 16 October 2015. Retrieved 21 September 2011.
  15. "M25 Junctions 12 to 15 widening". Archived from the original on 2012-03-17. Retrieved 2011-09-21. In 2003, Balfour Beatty Civil Engineering was awarded the £148 million contract to widen the 10-mile stretch of the M25, between Junction 12 (the M3 Interchange) and Junction 15 (the M4 Interchange).
  16. "M25 Jct 12 to 15 Widening". Highways Agency. Archived from the original on 2012-08-03. Retrieved 2011-09-21.
  17. 17.0 17.1 Boazman, Sally 2011. M25: 10 ways it has changed lives. BBC News
  18. "Tunnel Test 2004 - Dartford Tunnel" (PDF). AA Motoring Trust. September 2004. p. 3. Retrieved 22 May 2010.
  19. 19.0 19.1 "M25 Road Network Driver Location Signs" (PDF). Highways Agency. Archived from the original (PDF) on 5 June 2011. Retrieved 9 June 2009.
  20. Asher 2018, p. 121.
  21. "M25". roads.org.uk. Retrieved 19 July 2019.
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