The M25 Iver Heath crash has stopped all lanes of the motorway near Iver Heath on Tuesday morning, triggering long queues and major disruption for drivers on one of Britain’s busiest roads.
The incident was first reported at around 11am on September 29, when traffic alerts confirmed every lane of the motorway had been halted at Iver Heath, on the western stretch of the M25 near the Buckinghamshire border.
Within minutes, congestion was building rapidly on the approaches to the scene, with drivers warned to expect significant delays while the closure remains in force. No further details about the vehicles involved have been confirmed at this stage.
This is a developing story — check back for updates.
What we know so far
The crash was first flagged shortly after 11am on Tuesday, with initial traffic reports stating that all lanes of the M25 had been stopped at Iver Heath.
By 11:05am, the closure was still in place and major traffic was building behind the scene, with queueing traffic stretching back along the approaches.
Motorists travelling through this section of the motorway are being advised to check conditions before setting off and to allow considerably more time for their journeys.
What this means for drivers
A full closure of the M25 is among the most disruptive incidents possible on the UK road network. With every lane stopped, traffic has nowhere to go — and on a road this busy, the tailbacks grow at an alarming rate.
Drivers planning to use the western section of the M25 today should:
- Check live traffic information before setting off, and keep checking it during the journey;
- Allow plenty of extra time, as delays of an hour or more are possible while a full closure is in place;
- Expect surrounding routes through Iver Heath, Uxbridge, Slough and nearby villages to be far busier than usual as traffic looks for alternatives;
- Follow sat-nav guidance or official diversion advice rather than improvising routes through unfamiliar local roads;
- Keep the hard shoulder clear unless directed otherwise, and leave room for emergency vehicles to get through.
Anyone travelling to or from Heathrow Airport, or moving between the M40 and M4 corridors, should prepare for knock-on disruption across a wide area of west London and the Thames Valley.
When every lane stops, queues stretch for miles
The M25 is the busiest motorway in Britain, carrying the orbital traffic of the entire capital around London. When all lanes are held, stationary traffic can extend for several miles within half an hour — and the backlog takes far longer to clear than the incident itself.
Iver Heath sits on the western arc of the motorway, a stretch that funnels traffic between the M40 towards the Midlands, the M4 towards the West Country and Wales, and the approaches to Heathrow Airport. A closure here does not only affect local drivers; it sends ripples across the wider road network, with diversionary routes quickly becoming congested in turn.
It is the latest in a run of disruptive incidents on the capital’s major roads. A crash near Potters Bar blocked two clockwise lanes of the M25 as queues built, while emergency crews were scrambled to the M25 near Enfield after a lorry crash. Drivers on the North Circular also faced major disruption after a four-vehicle crash blocked part of the road near Brentfield Road.
With incidents stacking up across different sections of the network in the same week, drivers are urged to check their full route — not just the M25 — before heading out.
How long could the disruption last?
Once a crash forces a full closure of the motorway, the road typically remains shut until any vehicles involved have been recovered and the carriageway has been checked and cleared. Depending on the severity of the incident, that can take anywhere from under an hour to several hours.
Even after lanes reopen, the queues do not simply vanish. Traffic caught in a full closure can take a long time to get moving again, and the recovery wave travels slowly back through standing traffic — meaning delays often persist well after the road itself has reopened.
With this incident striking late in the morning, there is a real prospect of disruption spilling over into the lunchtime period and beyond, particularly if the closure drags on.
Developing story
Details remain limited at this stage and the situation on the ground can change quickly. We will continue to update this article as more information becomes available. Drivers are advised to check the latest traffic information before travelling and to avoid the area around Iver Heath if possible.
