M25 motorway

The M25 motorway or London Orbital motorway is a 117 mi motorway that almost encircles Greater London, England, in the United Kingdom. A narrower concept was first mooted early in the 20th century as part of the plan to build four ring roads around London. A few sections, based on the abandoned London Ringways plan, were constructed in the early 1970s and it was completed in 1986.

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

Although technically not an entire orbital motorway – a short non-motorway stretch forms the Dartford Crossing (A282) – the M25, at 117 mi is Europe's second longest orbital road after the Berliner Ring, which is 122 mi.

Description
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.

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 from 12.5 mi in Potters Bar to 19.5 mi in Byfleet. Three Greater London Boroughs (Enfield, Hillingdon and Havering) have realigned their boundaries to the M25 for minor stretches; while in others, most notably in Essex and Surrey, the radial gap between Greater London and the motorway reaches 7.8 mi, neither of which coincide with the Metropolitan Green Belt. Major towns listed as destinations (right), in various counties, adjoin the M25. North Ockendon is the only settlement of Greater London situated outside the M25. In 2004, following an opinion poll, the London Assembly mooted for consultation alignment of the Greater London boundary with the M25. "Inside the M25" and "outside/beyond the M25" are colloquial, looser alternatives to "Greater London" sometimes used in haulage. The Communications Act 2003 explicitly uses the M25 as the boundary in requiring a proportion of television programmes to be made outside the London area.

Two Motorway service areas are on the M25 and two are directly accessible from it: Clacket Lane between junctions 5 and 6 (in the south-east) and Cobham between junctions 9 and 10 (in the south-west). Those directly accessible from it are South Mimms off junction 23 (to the north of London) and Thurrock off junction 31 (to the east of London). Cobham services opened on 13 September 2012.

The M25 is broadly lit to help reduce accidents. Current illuminated sections are Dartford to junction 3, junction 5, junctions 6 to 21a and junctions 23 to 31. The type of lighting varies. Some sections use the older yellow low-pressure sodium (SOX) lighting while others use modern high-pressure sodium (SON) lighting. Some stretches have recently been upgraded to SON lighting. These include Junction 5, junctions around Heathrow and Junction 27.

The motorway passes through six counties, as well as some of Greater London. Junctions 1a–5 are in Kent, 6–13 are in Surrey, apart from a small stretch between junctions 12 and 13 which is in Berkshire. Junction 14 is on the Surrey – Greater London border, 15 is on the Buckinghamshire, Berkshire and Greater London border, 16 is in Buckinghamshire, 17–24 are in Hertfordshire, 25 is in Greater London (the Hertfordshire border going around the junction's northern edge), 26–28 in Essex, 29 in Greater London and 30–31 in Essex. Policing of the road is carried out by an integrated policing group made up of the Metropolitan, Thames Valley, Essex, Kent, Hertfordshire and Surrey forces.

The M25 is one of Europe's busiest motorways. In 2003, a maximum of 196,000 vehicles a day were recorded on the motorway just south of London Heathrow Airport between junctions 13 and 14.

Plans and construction
A precursor of the M25 was the North Orbital Road (see A414 road).

The idea of an orbital road around London was first proposed early in the 20th century and then re-examined in Sir Charles Bressey's and Sir Edwin Lutyens' The Highway Development Survey, 1937. Sir Patrick Abercrombie's County of London Plan, 1943 and Greater London Plan, 1944 proposed a series of five roads encircling the capital. The northern sections of the M25 follow a similar route to the World War II Outer London Defence Ring.

Little was done to progress these plans until the 1960s when the Greater London Council developed their London Ringways plan consisting of four "rings" around the capital. Sections of the two outer rings – Ringway 3 (the 'M16 motorway') and Ringway 4 – were constructed in the early 1970s and were integrated into the single M25 orbital motorway. But the Ringways plan was hugely controversial owing to the destruction required for the inner two ring roads, (Ringway 1 and Ringway 2). Parts of Ringway 1 were constructed (including West Cross Route and Westway), against stiff opposition, before the overall plan was abandoned in 1973 following pressure from residents in the threatened areas.

Construction of parts of the two outer ring roads, Ringways 3 and 4, began in 1973. The first section, between South Mimms and Potters Bar in Hertfordshire (junction 23 to junction 24) opened in September 1975 and was given the temporary general purpose road designation A1178; a section south of London (junction 6 to junction 8) opened in 1976. A section of Ringway 3 south of the river between Dartford and Swanley (junction 1 to junction 3) was constructed between 1974 and 1977. In 1975 the plans for Ringway 3 were modified to combine it with Ringway 4, the outermost Ringway. The M25 as a component of ringway 4, was first conceived to be an east-west road south of London to relieve the A25, and running parallel to it, with its eastern end following the route of what is now the M26. However, it was subsequently routed northwards towards the Dartford Tunnel to form, in conjunction with similar roads, including the M16 planned to the north of London, part of the London Orbital. The combined motorway was given the designation M25 which had originally been intended for the southern and western part of Ringway 4 and the M16 designation was dropped. The section of Ringway 3 west of South Mimms anti-clockwise around London to Swanley in Kent was cancelled. The stages were not constructed contiguously but in small sections. As the orbital road developed the sections were linked. Each section was presented to planning authorities in its own right and was individually justified, with 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 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.

Operational history
Soon after the motorway opened in 1986 traffic levels exceeded maximum designed capacity and in 1990 the Secretary of State for Transport announced plans to widen the whole of the M25 to four lanes. By 1993 the motorway that was designed for a maximum of 88,000 vehicles per day was carrying 200,000, 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

In parts, particularly the western third this plans went ahead, given consistent congestion however again plans to widen further sections to eight lanes (four each way) were scaled back in 2009 in response to rising costs, which are reinstated in the agreed Highways Agency 2013-14 business plan.

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 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, and has improved traffic flow slightly, and reduced the amount of start-stop driving.

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 and it was cancelled shortly afterwards. 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. Environmental groups objected to the decision to go ahead a scheme that would create the widest motorways in the UK without holding a public inquiry. The decision was again deferred. A decision to go-ahead was given for a 10-lane scheme in 1998 and the £148 million 'M25 Jct 12 to 15 Widening' contract was awarded to Balfour Beatty in 2003. The scheme was completed in 2005 as dual-five lane between junctions 12 to 14 and dual six lanes from 14 to 15.

In 2007 capacity at junction 25 (A10/Waltham Cross) was increased and the Holmesdale Tunnel was widened to 3 lanes in an eastern direction at a cost of £75 million.

Work to widen the exit slip-roads in both directions at Junction 28 (A12 road/A1023) was completed in 2008. It was designed to reduce the amount of traffic queueing on the slip roads at busy periods, particularly traffic from the clockwise M25 joining the northbound A12 where the queue can extend onto the inside lane of the Motorway.

Design, Build, Finance and Operate (DBFO) contract
In 2006 the Highways Agency proposed to widen 63 mi of M25 from six to eight lanes, between junctions 5–6 and 16–30 as part of a Design, Build, Finance and Operate (DBFO) project. A shortlist of contractors was announced in October 2006 for the project which was expected to cost £4.5 billion. Contractors were asked to resubmit their bids in January 2008 and in June 2009 the new transport minister indicated that the cost had risen to £5.5 billion and the benefit to cost ratio had dropped considerably. In January 2009 the government announced that plans to widen the sections from Junction 5–7 and from 23–27 had been 'scrapped' and that hard shoulder running would be introduced instead. However widening has been reinstated to four lanes in the 2013-14 Highways Agency Business Plan

In 2009 a £6.2 billion M25 'Design, Build, Finance and Operate' (DBFO) private finance initiative contract was awarded to Connect Plus to widen the sections between junctions 16 and 23 and between junctions 27 and 30 and maintain the M25 and the Dartford Crossing for a 30-year period.

Works to widen the section between junctions 16 and 23 (M40-A1(M)) to dual 4 lanes started in July 2009 at an estimated cost of £580m; The J16-21 section (M40 to M1) was completed by July 2011 and from J21-23 (M1 to the A1(M)) by June 2012. Works to widen the J27-30 section (M11-A13) to dual 4 lanes started in July 2009. J27-28 (M11-A12) was completed in July 2010, J28-29 (A12-A127) in June 2011 and J29-30 (A127-A13) in May 2012.

M25 Jct 5 to 7 managed motorway
The Highways Agency plans to introduce managed motorway with hard shoulder running on the M25 from Junctions 5 to 7 (A21/M26 – M23). Initial work started with barrier upgrades in late 2012, and the main works are set to be complete in spring 2015.

M25 Jct 23 to 27 managed motorway
The Highways Agency plans to introduce managed motorway with hard shoulder running on the M25 from Junctions 23 to 27 (A1(M)-M11), with work taking place between early 2013 and February 2015.

Junction 30 improvement
Preparation work to increase capacity at Junction 30 (Thurrock) as part of the Thames Gateway Delivery Plan is underway although there is no guarantee of delivery. Plans were announced in 2007. An early estimate on the start of major works was given as 2013/2014. Philip Hammond has confirmed that there will be no funding for the J30 improvements in this spending period, but has announced that preparation work would continue so that the scheme could be funded at a later date.

Lower Thames Crossing
In 2009 the Department for Transport published options for a new Lower Thames Crossing to add capacity to the Dartford Crossing or create a new road and crossing linking to the M2 and M20 motorways.

Comparisons
Other cities encircled by motorways include Manchester using the M60, Birmingham using parts of the M5, M6 and M42 and from 2011 Glasgow has an orbital motorway made of the M8, M73 and M74 although one section of the route passes through the centre of the city. The M25 is the second-longest ring road in Europe, after the Berlin Ring (A 10) which is 5 mi longer. The M25 is one of the busiest motorways in Europe:


 * M25 around London: 196,000 vehicles a day recorded in 2003 between junctions 13 and 14 near London Heathrow Airport.
 * A23 (Vienna): more than 200,000 vehicles on an average day.
 * A 100 (Berlin): 216,000 vehicles in a day was recorded in 1998
 * A4 motorway (near Paris): 257,000 vehicles a day recorded in 2002.
 * Moscow Ring Road: more than 250,000 vehicles on an average day.
 * Saint Petersburg Ring Road: more than 150,000 vehicles on an average day.
 * Grande Raccordo Anulare (Rome): more than 160,000 vehicles on an average day.

Popular culture
Iain Sinclair's book and film London Orbital, which was published in 2002, is based on a year long journey around the M25 on foot.

The M25 (including the A282 Dartford Crossing) is known for its frequent traffic 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", "the London Orbital Car Park") and songs (Chris Rea's "The Road to Hell").

The M25 plays an important role in the comedy-fantasy novel Good Omens, being "evidence for the hidden hand of Satan in the affairs of Man". The demon character, Crowley, had manipulated the design of the M25 to resemble a Satanic sigil.

The M25 enjoyed a more positive reputation among ravers in the late 1980s when this new orbital motorway became a popular route to the parties that took place around the outskirts of London. This use of the M25 for these raves inspired the name of electronic duo Orbital.

Racing


The orbital nature of the motorway, in common with racetracks, lent itself to unofficial, and illegal, motor racing. At the end of the 1980s, before the advent of speed enforcement devices, owners of supercars, many employed in the financial service industry in the City and in Docklands, would meet at night at service stations such as South Mimms and conduct time trials. Times below 1 hour were achieved; an average speed of over 117 mph (188 km/h), which included coming to a halt at the Dartford Tunnel road user charge payment booths.

Junctions
Data from driver location signs provide carriageway identifier information. The numbers on the signs are kilometres from a point near the River Thames, east of London, when travelling clockwise on the motorway. The table below gives details of each junction, including the roads interchanged and the destinations that are signed from the motorway. Figures in kilometres are from the driver location signs; figures in miles are derived from them.

{| class="wikitable" !scope=col| miles !scope=col| km !scope=col| Clockwise exits (A carriageway) !scope=col| Junction !scope=col| Anti-clockwise exits (B carriageway) Maidstone M20 Swanley B2173 London (SE & C), Lewisham A20 Orpington A224 Orpington (A224) Sevenoaks, Hastings A21 Westerham (A25) Redhill (A25) Redhill (A25) Harrow (M1 South) London (North West) (M1 (South)) London (North West) A1 Barnet A1081 South Mimms services Services Barnet A1081, Services Brentwood A1023 Brentwood A1023
 * - align="center" bgcolor="00703C" style="color: #FFD200;font-size:120%;"
 * colspan="5" | A282 road – Dartford Crossing
 * - align="center"
 * Dartford Crossing A282 Queen Elizabeth Bridge
 * River
 * Dartford Crossing A282 Dartford Toll Tunnel
 * - align="center"
 * 3.5
 * 5.7
 * Erith A206
 * J1a
 * Erith A206, Swanscombe (A226)
 * - align="center"
 * 4.7
 * 7.5
 * Dartford A225
 * J1b
 * Exit via J2 – Dartford (A225)
 * - align="center" bgcolor="0080d0" style="color: white;font-size:120%;"
 * colspan="5" | M25 motorway – London Orbital
 * - align="center"
 * 5.5
 * 8.8
 * London (South East), Canterbury A2, (M2), Bluewater
 * J2
 * London (SE & C), Lewisham A2(W), Canterbury A2(E) (M2), Dartford (A225)
 * - align="center"
 * 8.7
 * 14.0
 * London (South East) A20
 * 8.7
 * 14.0
 * London (South East) A20
 * J3
 * Maidstone, Channel Tunnel M20
 * - align="center"
 * 12.2
 * 19.6
 * Bromley A21
 * J4
 * Bromley, London (SE) A21
 * - align="center"
 * 16.3 16.4
 * 26.2 26.4
 * Sevenoaks, Royal Tunbridge Wells, Hastings A21
 * J5
 * Maidstone, Channel Tunnel, Dover M26 (M20)
 * - align="center"
 * 21.0
 * 33.8
 * Clacket Lane services
 * Services
 * Clacket Lane services
 * - align="center"
 * 25.8
 * 41.6
 * East Grinstead, Eastbourne, Caterham, Godstone A22
 * J6
 * Eastbourne, Caterham, Godstone A22, Westerham (A25)
 * - align="center"
 * 28.6
 * 46.0
 * Gatwick Airport, Crawley, Brighton, East Grinstead, Croydon M23
 * J7
 * Gatwick, Brighton, M23(S), Croydon M23(N)
 * - align="center"
 * 31.9
 * 51.4
 * London (South & South West), Reigate, Sutton A217
 * J8
 * London (South & South West), Reigate, Sutton A217
 * - align="center"
 * 38.5 39.5
 * 62.0 63.5
 * Leatherhead A243, Dorking, (A24), Chessington World of Adventures
 * J9
 * Leatherhead A243, Dorking (A24), Chessington World of Adventures
 * - align="center"
 * 42.6 43.2
 * 68.6 69.5
 * Cobham Services
 * Services
 * Cobham Services
 * - align="center"
 * 45.0
 * 72.4
 * London (South West & Central), Guildford, Portsmouth, Wisley RHS Garden, Sandown Park Racecourse, Hampton Court Palace
 * J10
 * London (South West), Guildford, Kingston, Wisley RHS Garden, Sandown Park Racecourse, Chessington World of Adventures
 * - align="center"
 * 49.8
 * 80.2
 * Chertsey A317, Woking A320, Thorpe Park
 * J11
 * Woking A320, Chertsey A317, Thorpe Park
 * - align="center"
 * 52.1
 * 83.8
 * Basingstoke, Southampton, Richmond M3
 * J12
 * Basingstoke, Southampton, Richmond M3
 * - align="center"
 * 55.2
 * 88.8
 * A30 London (West), Hounslow, Staines
 * J13
 * A30 London (West), Hounslow, Staines
 * - align="center"
 * 57.0
 * 91.8
 * Heathrow Airport (Terminals 4, 5 and Cargo) A3113 dedicated spur
 * J14
 * Heathrow Airport (Terminals 4, 5 and Cargo) A3113 dedicated spur
 * - align="center"
 * 59.0
 * 95.0
 * The West, Slough, Reading, London (West), Heathrow Airport (Terminals 1, 2 and 3) M4
 * J15
 * The West, Slough, Reading M4(W) London (W), Heathrow (Terminals 1, 2 & 3) M4(E)
 * - align="center"
 * 63.8
 * 102.6
 * The North, Birmingham, Oxford, Uxbridge, London (W,C) M40
 * J16
 * Birmingham, Oxford M40(W) Uxbridge, London (W & C) M40(E)
 * - align="center"
 * 68.7
 * 110.5
 * Maple Cross (A412)
 * J17
 * Maple Cross A412
 * - align="center"
 * 69.9
 * 112.5
 * Rickmansworth, Chorleywood, Amersham A404
 * J18
 * Chorleywood, Amersham, Rickmansworth A404
 * - align="center"
 * Watford A41
 * J19
 * No exit
 * - align="center"
 * 73.8
 * 118.7
 * Hemel Hempstead, Aylesbury A41
 * J20
 * Hemel Hempstead, Aylesbury, Watford A41
 * - align="center"
 * 76.3
 * 122.8
 * The North, Luton & Airport M1
 * J21
 * The North, Luton & Airport M1
 * - align="center"
 * 76.9
 * 123.7
 * Watford A405
 * 123.7
 * Watford A405
 * J21A
 * St Albans A405
 * - align="center"
 * 80.6
 * 129.7
 * London Colney A1081
 * J22
 * St Albans A1081
 * - align="center"
 * 83.3
 * 134.0
 * Hatfield A1(M)
 * J23
 * Hatfield A1(M), London (NW) A1
 * - align="center"
 * 85.9
 * 138.2
 * Potters Bar A111
 * J24
 * Potters Bar A111
 * - align="center"
 * 91.4
 * 147.1
 * Enfield Town, Hertford A10
 * J25
 * Enfield, Hertford, London (N & C) A10
 * - align="center"
 * 94.9
 * 152.7
 * Waltham Abbey, Loughton A121
 * J26
 * Waltham Abbey, Loughton A121
 * - align="center"
 * 99.2
 * 159.7
 * London (NE), Stansted Airport, Harlow, Cambridge M11
 * J27
 * London (NE & C) M11(N), Stansted, Harlow, Cambridge M11(S)
 * - align="center"
 * 107.1
 * 172.4
 * Chelmsford, Witham, Colchester A12
 * J28
 * Chelmsford, Romford A12
 * - align="center"
 * 109.9
 * 176.8
 * Romford, Basildon, Southend A127
 * J29
 * Basildon, Southend, Romford A127
 * - align="center"
 * 115.2
 * 185.4
 * Dagenham, Rainham, Tilbury, Barking, London (E & C) A13 Thurrock services
 * J30
 * Dagenham, Rainham, Tilbury, Basildon, London (E & C) A13, West Thurrock (A126)
 * - align="center"
 * - align="center" bgcolor="00703C" style="color: #FFD200;font-size:120%;"
 * colspan="5" | A282 Road – Dartford Crossing
 * - align="center"
 * 115.9
 * 186.6
 * Access via J30
 * J31 Services
 * Thurrock (Lakeside), Services A1306, Purfleet (A1090), West Thurrock (A126)
 * - align="center"
 * Dartford Crossing A282 Queen Elizabeth Bridge
 * River
 * Dartford Crossing A282 Dartford Toll Tunnel
 * colspan=5|Notes
 * Distances in kilometres and carriageway identifiers are obtained from driver location signs/location marker posts. Where a junction spans several hundred metres and the data is available, both the start and finish values for the junction are shown.
 * colspan=5|Notes
 * Distances in kilometres and carriageway identifiers are obtained from driver location signs/location marker posts. Where a junction spans several hundred metres and the data is available, both the start and finish values for the junction are shown.
 * Distances in kilometres and carriageway identifiers are obtained from driver location signs/location marker posts. Where a junction spans several hundred metres and the data is available, both the start and finish values for the junction are shown.

Anti-clockwise information above gathered from Advanced Direction Signs August 2011 (J9 – J22, J20 – J15)