Happy birthday M25

On this day back in 1986, Margaret Thatcher opened the M25 motorway. One of the biggest orbital motorways in Europe, it cost nearly £1 billion to build and has since gone on to be Britain's most infamous motorway…

Today, the M25 handles twice the amount of traffic it was designed for, has been upgraded many times and is the nation’s busiest motorway, by far.

As she cut the ribbon on 29 October, Prime Minister Margaret Thatcher said the orbital road around London was an “absolute necessity”. Since its opening, billions have been spent ensuring the M25 is generally, able to function as originally intended – despite now carrying a million people a day.

Here, we celebrate the M25, by looking into its history, how it’s developed over the years – and also some of the more offbeat stories it has generated over the years…

The longest traffic jam on the M25

The longest recorded traffic jam was in December 1995. It was 37 miles long.

The longest-ever stretch of completely stationary M25 traffic was in 1988. It was 22 miles long.

You can view the latest M25 traffic news on our route planner.

M25 facts and stats

Length: 117 miles

Build cost: £1 billion

Time taken to build: 14 years (1973-1986)

First section completed: J23-J24 A1 South Mimms-A111 Potters Bar: 1975

Last section completed: J22-J23 London Colney-A1 South Mimms: 1986

Number of interchanges: 31

Number of bridges: 234

Number of lights: 10,500 plus

Number of people using it daily: 1 million plus

Time to circle the M25 at the national speed limit: 1 hour 40 minutes

Original capacity: 88,000 vehicles a day

Current usage: Between 150,000-200,000 vehicles a day

Improvements over the years

1989: Orbit study recommends upgrading the M25 motorway from three lanes to four lanes in key sections (junctions 2, 3, 5, 6 and 7, and junctions 27-30). Work was completed in 1993.

1993: plans to widen junctions 8-10 from three lanes to four lanes commenced, at a cost of £93 million. Work was completed in 1995.

1995: The MIDAS motorway incident detection and automated signaling system was installed, between junctions 10-16.

1997: Plans to widen junction 12 (M4) and junction 15 (M3) from four lanes to as many as six lanes in each direction were revealed. There was much opposition: work finally began in 2003 and was completed in 2005.

2009: Massive £6.2 billion scheme to widen key sections of the M25, upgrade other areas and introduce the Managed Motorways system was revealed. Key upgrades for busy sections had to be complete by the London 2012 Olympics. They were.

Some things you might not know about the M25

  • The highest-ever recorded speed on the M25 was 147mph in 1992. The motorist, who was driving a Porsche 911 lost his licence.
  • 1990s band The Orbital were named after the M25. Chris Rea also wrote the song The Road To Hell after the motorway.
  • The first breakdown on the M25 came on 11.16am, October 29th, 1986 - just hours after it was opened...
  • Technically, the M25 is not an orbital motorway… because the Dartford Crossing section carries the road name A282. This is to ensure traffic prohibited from motorways, such as learner drivers, can still use the crossing.
  • Chris and Sue Glazier spent their wedding night driving around the M25.
  • In 2010, Alistair Humphreys and Rob Lilwall walked the entire length of the M25, to raise money for charity. They walked 150 miles and it took them six days: they slept in snowy forests along the way.
  • Before it was complete, sections of the M25 were labeled M16.