GEOTAB IDENTIFIES M25 CONGESTION BETWEEN JUNCTIONS 10 AND 20

Vehicle data company Geotab identified eight of the M25’s most congested stretches between junctions 10 and 20 as the motorway marked its 40th anniversary. The stretch includes interchanges with the M3, M4 and M40 and serves Heathrow. Geotab measured an average speed of 44.6mph between junctions 15 and 16, about 64 per cent of the 70mph speed limit. Its analysis examined 46 of the motorway’s 58 directional sections across 12 sample weeks between September 2025 and August 2026. The M25’s final section opened in 1986.

Geotab’s figures put the average clockwise journey between junctions 14 and 15 at 9.2 minutes at 4pm, compared with three minutes at 7pm. An anticlockwise journey between junctions 17 and 16 took an average of 15.6 minutes at 7am, compared with 6.6 minutes at 7pm. The company recorded 659 periods when a section’s speed fell to 70 per cent or less of its normal level. It said 236 of those periods lasted at least two hours. Geotab recorded the most disruptions on Mondays and Fridays.

Geotab vice-president Aaron Jarvis said freight, airport traffic and commuters join and leave the M25 within a few miles of each other. “That constant merging is what slows the flow,” he said. In a survey of 1,000 van drivers based in the South East, Geotab found that 84 per cent said their businesses could not operate effectively without the motorway. Four in five respondents said they considered the M25 less reliable than before the COVID-19 pandemic. Geotab said better planned roadworks and faster responses to incidents could improve journeys.