The notorious M25 is the second longest city bypass in Europe at 117 miles in length.
It orbits Greater London, starting at the Dartford Crossing, and flows past a total of 33 junctions. It links motorways such as the M1, M4, A1, and the M40 making it a big part of the major road network in the UK and also one of the busiest. As the M25 is a vital link, it’s managed by the Highways Agency at two state-of-the-art control centres, one of which is at South Mimms.
Building started in 1975 in sections and was finished ahead of schedule in October 1986. The extensive project included planting more than 2.1 million trees and shrubs. Prime Minister Margaret Thatcher unveiled the finished road once the last Hertfordshire section was completed.
When driving on the M25 you’ll find that variable speed limits have been introduced to manage traffic flow during peak times, so you may want to keep in the know with any M25 travel updates before your journey begins.
The M25 goes over or under 234 bridges, one of which is the iconic Dartford-Thurrock River Crossing. You’ll need to pay the Dart Charge to cross the River Thames. The crossing uses automatic number plate recognition to record each car as you drive across. This means you’ll have to pay online or by phone as there are no barriers to pass through. The charge is only valid when traveling outside of 10pm to 6am.
Worst Junctions on the M25
The M25 has evolved over time with new junctions connecting London with major motorways that flow traffic around the rest of the UK. This road does get very busy, but these junctions are some of the worst traffic hotspots, so it may be worth checking the RAC Route Planner for up to date M25 travel news before you travel.
Junction 23 - The South Mimms Interchange has flowing traffic from the M25, the A1 and the A1081. With two vital road networks meeting, there’s bound to be a build up of traffic, which is only worsened by the five sets of traffic lights around the roundabout.
Junction 21 – The Chiswell Interchange is a known issue mainly for the drivers wanting to join the M1 here to head south into London, as there’s no connection road. To travel south you’ll need to exit at Junction 20 for the A41, which can take longer.
Junction 5 - The Chevening Interchange is problematic due to the M25 not having priority over the M26 which joins this route. This means traffic will build up as only a two-laned slip road carries the M25 south west.
Dartford Tunnel - As well as paying a toll fee, the major road crossing is limited to just 50 mph in both directions. This can get congested especially during peak times of the day.
Accident Hotspots on the M25
The M25 is one of the busiest roads in the UK with hundreds of thousands of users travelling on it every day. When joining the M25 you may want to be mindful of the below accident blackspots. Plan your journey with the RAC Route Planner and keep up to date with any major M25 traffic updates.
The section from the Dartford Crossing up until junction 4 has been known to be a problematic area. This may be because of the increase and decrease of lanes throughout the bridge and tunnel crossing. Be mindful of this and allow yourself plenty of time to cross safely.
There have been previously reported accidents by junction 28, which could be attributed to the growing number of road users in the area and the problematic roundabout. Conditions on junction 28 are due to improve with plans to rework the road and roundabout structure starting in 2021.
Upcoming M25 Major Roadworks
The M25 is one of the busiest motorways in the UK orbiting a great distance around London. With this in mind, ongoing plans to maintain the condition of the motorway may cause future roadworks. Keep up to date with any M25 traffic news with the RAC Route Planner app to note any M25 travel updates and reported delays.
Upcoming major roadworks on the M25 include:
Junction 10 - With the aim of improving congestion in the area, this is a major project. Planned to start in 2020/21, the project is to increase road capacity at the roundabout and between Ockham and Painshill on the A3. The cost could be as much as £250m.
Junction 10 to Junction 16 - Turning this part of the M25 into a smart motorway to reduce congestion and improve journey time, this project is planned to start in 2020/21.
Junction 25 - These are improvements to increase road capacity which will reduce traffic build up. This project is planned to start in 2020/21.
Junction 28 - Planned to start in 2021/22, this major scheme aims to improve congestion and reduce incident rate by redesigning the original road structure.