M25 motorway

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

M25 motorway
London Orbital Motorway
Junction 13 looking south
Route information
Part of and
Maintained by Connect Plus (contracted to Highways England)
Length	117 mi (188 km)
Existed	1975–present
History	Opened: 1975 Completed: 1986
Major junctions
Orbital around London (along with the A282)
South end	Dartford (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 end	Thurrock (Dartford Crossing northern approach)
Road network
Roads in the United Kingdom Motorways A and B road zones
← →

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.

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.

Planning

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". 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. 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. 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 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. The system has improved traffic flow slightly, and reduced the amount of start-stop driving. 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, 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 without holding a public inquiry. 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.

Costs

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.

Dartford

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.

Consequences

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

• 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."

Junctions

A282 (Dartford Crossing)
miles	km	Clockwise exits (A carriageway)	Junction	Anti-clockwise exits (B carriageway)	Opening date
0.0	0.0	Dartford Crossing South (Queen Elizabeth II Bridge)	River Thames	Dartford Crossing North (Dartford Tunnels)	November 1963 (west tunnel) May 1980 (east tunnel) October 1991 (bridge)
3.5	5.7	Erith A206	J1A	Erith A206, Swanscombe (A226)	September 1986
4.7	7.5	Dartford A225	J1B	Exit via J2 – Dartford (A225)	September 1986
M25
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) Hayes	February 1986
16.3 16.4	26.2 26.4	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)
38.5 39.5	62.0 63.5	Leatherhead A243, Dorking, (A24)	J9	Leatherhead A243, Dorking (A24)	October 1985
42.6 43.2	68.6 69.5	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)	River Thames	Dartford Crossing North (Dartford Tunnels)	November 1963 (west tunnel) May 1980 (east tunnel) October 1991 (bridge)
Notes 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