Who uses the M25?  21 Dec 2020

Only a small proportion (14%) of car and taxi trips on the M25 – one of the longest and busiest ring roads in the world – bypass London completely and are made by people travelling from one part of the country to another.

The vast majority (74%) of car and taxi trips that include the M25 actually start or end in London.

The remaining proportion (12%) of car and van trips are so-called intra-London movements, meaning the journeys both start and end in the capital but use the 117-mile-long orbital motorway as part of the route.

The M25 was built in stages with the final section being opened by the-then Prime Minister Margaret Thatcher in 1986.

The journey analysis, conducted by consultancy firm Atkins, a member of the SNC-Lavalin Group, and global location technology firm, TomTom, studied more than 4.4 million anonymous car and taxi trip movements from GPS device traces during weekdays (Monday-Friday) in November 2019. These traces were captured from in-dashboard, on-dashboard and mobile navigation technologies.

The analysis revealed that of the strategic routes “feeding” the M25, the M1 was the most significant, followed by the M4, M3, M40 and A2.

The study also revealed that:

  1. 7-8am and 4-5pm are the peak hours for traffic on the M25.
  2. Key destinations such as ports and airports exerted big influences on M25 traffic.
  3. Drivers undertaking strategic trips circumnavigating London using the M25 tend to travel earlier in the day, exacerbating congestion in the morning peak.
  4. For strategic trips using the M25 between different parts of the country, movements between Surrey, Gatwick (M23) and Kent (M26) were particularly notable, confirming the lack of alternative high-capacity cross-country routes along the south coast.

Strategic movements between “the shires” (M11) and Essex (A127) were boosted by roadworks affecting the A14 during this time, highlighting again the need for clear communication between road operators and road users during strategic construction projects.

The initial research was conducted by Atkins and TomTom for the RAC Foundation’s Data Driven 2020 event. An interview with the authors is available on the RAC Foundation website together with their presentation.

Steve Gooding, director of the RAC Foundation, said:

“This unique research addresses one of the great mysteries of life: where are all those cars on the M25 actually going? Now we know, and most of them are not trying to avoid the capital.

“This might come as a surprise to the many of us who think of the M25 as a way of avoiding London rather than travelling in, out or through it.

“This data should be of keen interest to those responsible for the management of the M25 and of the many local roads that connect with it.

“A possible follow up to this important work could be a look at where freight journeys on the M25 are starting and ending.”

Sean Flynn of Atkins said:

“This research, underpinned by the robust and easy-to-use origin destination tool of TomTom, was a good opportunity for Atkins to demonstrate our traffic data analytics capabilities. We believe the initial outcomes will be of interest to a number of our customers and that M25 movements merit further investigation.”



Philip Gomm – Head of External Communications – RAC Foundation

[email protected] | 07711 776448

Notes to editors:

The RAC Foundation is a transport policy and research organisation that explores the economic, mobility, safety and environmental issues relating to roads and their users.

The Foundation publishes independent and authoritative research with which it promotes informed debate and advocates policy in the interest of the responsible motorist.


TomTom is the leading independent location technology specialist, shaping mobility with highly accurate maps, navigation software, real-time traffic information and services. To achieve our vision of a safer world, free of congestion and emissions, we create innovative technologies that keep the world moving. By combining our extensive experience with leading business and technology partners, we power connected vehicles, smart mobility and, ultimately, autonomous driving. Headquartered in Amsterdam with offices in 30 countries, TomTom’s technologies are trusted by hundreds of millions of people worldwide.


SNC-Lavalin’s Atkins business is one of the world’s most respected design, engineering and project management consultancies. We build long-term trusted partnerships to create a world where lives are enriched through the implementation of our ideas.

Employing over 18,300 people across the UK, North America, Middle East and Africa, Asia Pacific and Europe, clients come to us for transformational solutions. Whether it’s creating something new or finding ways to get more out of what we already have, we’re known for thinking differently and delivering value.

Atkins helps clients plan, design and enable major capital projects, and provides expert consultancy that covers the full project lifecycle across infrastructure, transportation, nuclear and power, oil and gas, engineering and design, water, the environment, defence, aerospace, communications, project management and architecture.