Editing M25 motorway (section)

==Description==
===Route===
[[File:070921-Final DLS map.pdf|thumb|left|300px|Map of the M25 showing the junction numbers and driver location signs]]

The M25 almost completely encircles [[Greater London]] and passes briefly through it, in the east and west.<ref>{{cite web | url = https://s3-eu-west-2.amazonaws.com/lgbce/Reviews/Greater%20London/Havering/(SI%202021-000)%20-%20Draft%20LB%20of%20Havering%20(Electoral%20Changes)%20Order%20Map.pdf | title = Map referred to in the London Borough of Havering (Electoral Changes) Order 2021 | year = 2021 | website = [[Boundary commissions (United Kingdom)|The Local Government Boundary Commission for England]] | access-date = 27 October 2022 | archive-url = https://web.archive.org/web/20220406201316/https://s3-eu-west-2.amazonaws.com/lgbce/Reviews/Greater%20London/Havering/(SI%202021-000)%20-%20Draft%20LB%20of%20Havering%20(Electoral%20Changes)%20Order%20Map.pdf | archive-date = 6 April 2022}}</ref><ref name=Heathrow>{{cite web | url = https://hillingdon.gov.uk/media/7977/Heathrow-Villages-ward/pdf/Heathrow_Ward.pdf | title = Heathrow Villages ward map | year = 2022 | website = [[London Borough of Hillingdon]] | access-date = 27 October 2022 | archive-url = https://web.archive.org/web/20220525121027/https://www.hillingdon.gov.uk/media/7977/Heathrow-Villages-ward/pdf/Heathrow_Ward.pdf | archive-date = 25 May 2022}}</ref> Junctions 1A–5 are in [[Kent]], 6–13 are in [[Surrey]], 14 and a small part of 15 are in [[London Borough of Hillingdon|Hillingdon]], Greater London, 15–16 are in [[Buckinghamshire]], 17–24 are in [[Hertfordshire]], 25 is in [[London Borough of Enfield|Enfield]], Greater London and 26–31 are in [[Essex]].<ref name=Heathrow /> Law enforcement on the road is carried out by an integrated group made up of the [[Metropolitan Police Service|Metropolitan]], [[Thames Valley Police|Thames Valley]], [[Essex Police|Essex]], [[Kent Police|Kent]], [[Hertfordshire Constabulary|Hertfordshire]] and [[Surrey Police|Surrey]] police services.{{sfn|Hamilton|2015|p=24}} [[Roads in the United Kingdom#Primary destinations|Primary destinations]] signed ahead on the motorway include the [[Dartford Crossing]], [[Sevenoaks]], [[Gatwick Airport]], [[Heathrow Airport]], [[Watford]], [[London Stansted Airport|Stansted Airport]] and [[Brentwood, Essex|Brentwood]].<ref>{{cite web|url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/203664/traffic-signs-manual-chapter-02-primary-route.pdf|title=Traffic Signs Manual Chapter 2 : Primary Routes|publisher=Department of Transport|access-date=14 May 2019}}</ref>

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]]. The crossing consists of twin two-lane tunnels and the four-lane [[QE2 Bridge|QE2 (Queen Elizabeth II) bridge]],<ref name=AATrust>{{cite web|url=http://www.theaa.com/public_affairs/reports/dartford_tunnel_test_2004.pdf|title=Tunnel Test 2004 – Dartford Tunnel|date=September 2004|page=3|publisher=[[AA Motoring Trust]]|access-date=22 May 2010|archive-url=https://web.archive.org/web/20170108211825/http://www.theaa.com/driving-advice/driving-costs/dartford-crossing-dart-charge|archive-date=8 January 2017}}</ref><ref>{{cite web|url=https://pla.co.uk/Safety/Thames-Bridges-Heights|title=Thames Bridges Heights|publisher=Port of London Authority|access-date=7 August 2016}}</ref> with a main span of {{convert|450|m|ft}}.<ref>{{cite book|url=https://books.google.com/books?id=_h39X2cspQ0C&q=dartford+crossing+450+metres&pg=PA26|title=Bridge|first=Peter|last=Bishop|publisher=[[Reaktion Books]]|page=26|year=2008|isbn=978-1-861-89346-8}}</ref> Passage across the bridge or through the tunnels is subject to a [[road pricing|charge]] between 6 am and 10 pm, its level depending on the kind of vehicle. The road is not under motorway regulations so that other traffic can cross the Thames east of the [[Woolwich Ferry]];{{efn|Pedestrians and cyclists cannot directly use the Dartford Crossing, but a shuttle service is available for the latter.<ref>{{cite web|url=https://www.gov.uk/dartford-crossing-bike|title=Get across the Dartford crossing by bike|work=HM Government|access-date=13 May 2019}}</ref>}} the only crossing further to the east is [[Gravesend-Tilbury Ferry|a passenger ferry]] between [[Gravesend]], [[Kent]], and [[Tilbury]], [[Essex]].<ref>{{cite news|url=https://www.kentonline.co.uk/gravesend/news/walk-on-to-cross-the-4983/|title=Walk on to cross the water|work=Kent Online|date=23 August 2013|access-date=14 May 2019}}</ref>

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 road (England)|A21]]. In the opposite direction, to the east of the point where the M25 diverges from the main east–west carriageway, that carriageway becomes the [[M26 motorway]].<ref name=J5>{{cite web|title = M25 in South East Region|publisher = The Motorway Archive|url = http://www.ukmotorwayarchive.org/|year = 2009|at = (Select "M25" from list of motorways, then "M25 interchanges, tunnels and bridges")|access-date = 18 April 2013}}</ref> From here to junction 8, the M25 follows the edge of the [[North Downs]] close to several historic buildings such as [[Chevening]], [[Titsey Place]], [[Hever Castle]] and [[Chartwell]].<ref name=leadbetter>{{cite news|url=https://www.telegraph.co.uk/travel/destinations/europe/united-kingdom/articles/m25-road-trip-best-sights/ |archive-url=https://ghostarchive.org/archive/20220112/https://www.telegraph.co.uk/travel/destinations/europe/united-kingdom/articles/m25-road-trip-best-sights/ |archive-date=12 January 2022 |url-access=subscription |url-status=live|title=10 reasons why a lap of the M25 is Britain's ultimate road trip|newspaper=The Daily Telegraph|date=29 October 2016|access-date=28 May 2019}}{{cbignore}}</ref><ref name=barkham>{{cite news|url=https://www.theguardian.com/world/shortcuts/2012/feb/21/coach-tour-m25|title=Coach tour of the M25 – a great day out|first=Patrick|last=Barkham|newspaper=The Guardian|date=21 February 2012|access-date=28 May 2019}}</ref> The interchange with the [[M23 motorway]] near [[Reigate]] is a [[Stack interchange#Four-level stack|four-level stack]]; one of only a few examples in Britain.{{sfn|Hamilton|2015|p=43}} Past this, the M25 runs close to the [[Surrey Hills National Landscape]].<ref name=leadbetter/>
[[File:M23-M25 Intersection - geograph.org.uk - 15455.jpg|thumb|Four level stack interchange at junction 7 with the M23]]
To the west, the M25 passes close to the edge of Heathrow Airport, and within sight of [[Windsor Castle]].<ref>{{cite news|url=https://www.independent.co.uk/travel/uk/trail-of-the-unexpected-the-m25-2088173.html|title=Trail of the unexpected: The M25|newspaper=The Independent|first=Simon|last=Calder|date=25 September 2010|access-date=28 May 2019}}</ref> North of this, it goes under the [[Chalfont Viaduct]] railway bridge, completed in 1906, which carries the [[Chiltern Main Line]]. [[Red kite]]s can often be seen overhead to the north of this, up to junction 21. The northern section of the M25 passes close to [[All Saints Pastoral Centre]] near [[London Colney]], [[Waltham Abbey]] and [[Copped Hall]].<ref name=leadbetter/><ref name=barkham/> This section also features two [[Tunnel#Cut-and-cover|cut-and-cover tunnels]], including the [[Bell Common Tunnel]].<ref name=barkham/> The north-eastern section of the motorway passes close to [[North Ockendon]], the only settlement of Greater London situated outside the M25.<ref name=independent_20161017/> It then runs close to the [[Rainham Marshes Nature Reserve]] before reaching the northern end of the Dartford Crossing.<ref name=leadbetter/>

In 2004, following an opinion poll, the [[London Assembly]] proposed aligning the Greater London boundary with the M25.{{efn|This move would be bound to be resisted by the communities affected, including Watford, [[Loughton]] and [[Epsom]].<ref>{{cite web|url=http://www.london.gov.uk/view_press_release_a.jsp?releaseid=3002|title=Poll says M25 is London's "natural boundary"|work=London Assembly|date=2 March 2004|archive-url=https://web.archive.org/web/20081009152623/http://www.london.gov.uk/view_press_release_a.jsp?releaseid=3002 |archive-date=9 October 2008 }}</ref>}} "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; it states a requirement of "a suitable proportion of the programmes made in the United Kingdom" to be made "in the United Kingdom outside the M25 area", defined in Section 362 as "the area the outer boundary of which is represented by the London Orbital Motorway (M25)".<ref>{{cite web| url=http://www.legislation.gov.uk/ukpga/2003/21 | title=Communications Act 2003 | publisher=The National Archives | year=2003 | access-date=5 September 2011}}</ref><ref>{{cite web|url=https://www.ofcom.org.uk/__data/assets/pdf_file/0017/7073/c4licence.pdf|title=Channel 4 Licence|publisher=[[Ofcom]]|access-date=20 May 2019}}</ref>

Sections of the M25 form part of two long-distance [[International E-road network|E-roads]], designated by the [[United Nations Economic Commission for Europe]]. The [[European route E15|E15]], which runs from [[Inverness]] to [[Algeciras]],{{sfn|United Nations Economic Commission for Europe|2016|p=11}} follows the M25 and A282 clockwise from the A1(M) at junction 23 to the M20 at junction 3;<ref name="AAAtlas"/> while the [[European route E30|E30]] [[Cork (city)|Cork]] to [[Omsk]] route runs from the M4 at junction 15, clockwise to the A12 at junction 28.<ref name="AAAtlas"/> The United Kingdom is formally part of the E-roads network but, unlike in other countries, these routes are not marked on any road signs.<ref>{{cite web |url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/2439/roadnetworkconsultation.pdf |author=[[Department for Transport]] |pages=13–14 |title=Road Network Policy Consultation |date=January 2011}}</ref>

===Features===

The M25 was originally built mostly as a dual three-lane motorway.{{sfn|Hamilton|2015|p=25}} Much of this has since 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 [[smart motorway]]s in many others.<ref name=bp/>

Two [[motorway service area]]s are on the M25, and two others are directly accessible from it. Those on the M25 are [[Clacket Lane services|Clacket Lane]] between junctions 5 and 6 (in the south-east) and [[Cobham services|Cobham]] between junctions 9 and 10 (in the south-west). Those directly accessible from it are [[South Mimms services|South Mimms]] off junction 23 (to the north of London) and [[Thurrock services|Thurrock]] off junction 31 (to the east of London).<ref name = cobhamServices>{{Cite web |publisher=[[Highways Agency]] |title=M25 MSA New Barn Farm Cobham |access-date=14 August 2010 |url=http://www.highways.gov.uk/roads/projects/26511.aspx|archive-url=http://webarchive.nationalarchives.gov.uk/20100303165935/http://www.highways.gov.uk/roads/projects/26511.aspx |archive-date=3 March 2010}}</ref><ref name=CobhamOpen>{{cite news |url=https://www.bbc.co.uk/news/uk-england-sussex-19583309 |title=Cobham M25 service station opened |date=13 September 2012 |work=[[BBC News]] |access-date=13 September 2012}}</ref>

As is common with other motorways, the M25 is equipped with emergency ("SOS") telephones. These connect to two [[National Highways]] operated control centres at [[Godstone]] (for junctions 1 to 15 inclusive) and [[South Mimms]] (for 16–31). The Dartford Crossing has a dedicated control centre. There is an extensive network of [[closed-circuit television]] (CCTV) on the motorway so incidents can be easily identified and located. A number of [[four-wheel drive|4×4]] vehicles patrol the motorway, attempting to keep traffic moving where possible, and assisting the local police. They can act as a [[rolling roadblock]] when there are obstacles on the road.{{sfn|Hamilton|2015|p=24}}

When completed, the M25 only had [[street lighting]] for {{convert|65|miles}} of its {{convert|117|miles|adj=on}} length.<ref>{{cite web|url=https://hansard.parliament.uk/commons/1986-02-06/debates/0a2b2f7d-26ea-4c54-90e7-7aa69c07f435/Roads(LightingAndSigns)|title=Roads (Lighting and Signs)|first=Nicholas|last=Ridley|author-link=Nicholas Ridley, Baron Ridley of Liddesdale|work=Hansard|date=6 February 1986|access-date=13 May 2019}}</ref> Originally, [[sodium vapor lamp|low pressure sodium]] (SOX) lighting was the most prominent technology used, but this has been gradually replaced with high-pressure sodium (SON) lighting. {{asof|2015}} the motorway has more than 10,000 streetlights.{{sfn|Hamilton|2015|p=26}} The M25 has a number of pollution control valves along its length, which can shut off drainage in the event of a chemical or fuel spill.{{sfn|Hamilton|2015|p=26}}