M25 section in Surrey collapses following roadworks
Three lanes of the M25 have been closed after a section collapsed and left a large pothole, following roadworks.
Surrey Police said many vehicles had been left with damaged tyres after the road surface near Leatherhead fell in during heavy rain at about 05:30 GMT.
Highways workers cleared concrete debris from the anti-clockwise carriageway near junction nine.
Tailbacks of up to 16 miles have been reported with disruption expected through this evening's rush hour.
The Highways Agency said repairs could take until 22:00.
Delays are currently about 60 minutes with queues back to junction 11 at Chertsey.
A Highways Agency spokesman said: "Concrete repairs being carried out overnight failed to set.
"Maintenance crews had been working overnight to replace three sections of concrete road surface between junctions nine and 10.
"One of these concrete sections disintegrated and another section was showing signs of distress.
"We have people on the site repairing these sections and we will reopen the closed lanes as soon as it is safe to do so."
Delays for hours
Surrey Police said delays were expected to last for many hours.
Among the thousands caught up in travel chaos are those heading to Gatwick. The West Sussex airport is urging travellers to allow extra time for their journeys.
National Express tweeted: "All services between Heathrow & Gatwick Airports suspended until further notice. We are moving customers via London to Gatwick & Brighton."
The company has posted details of services that have been cancelled because of the M25 disruption on its website.
One resident who lives beside the M25 said her family heard "very large, odd thuds, a bit like thunder at about 05:30.
"At one point our house was shaking and a piece of plaster fell out of the ceiling," she said.
"I don't know whether the thuds were the lorries hitting the hole or the road collapsing.
"It doesn't look enormous, but it is causing chaos."
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A caller to BBC Surrey said she joined the M25 at Weybridge at 07:30 and by 10:45 had got as far as Cobham services.
"We're going nowhere fast," she said.
"Nobody is giving any information about what is going on, which is no help."
At the scene
Adrian Harms, BBC Surrey reporter
There are now a lot more people on the motorway looking into the hole which is causing all these problems.
The bad news if you are a motorist is that the queues are still horrendous. There is just one lane open past the scene and that is lane four.
A mixture of vans and lorries and cars are parked up in lanes one to three and on the hard shoulder - presumably looking to repair the hole.
But from where I am standing that does not look as if it is going to be anytime soon.
Alex Goodwill tweeted: "Punctures galore thanks to pothole on M25 at Leatherhead".
AA president Edmund King said: "The M25 really is the road to hell today.
"There must be a thorough investigation into this incident.
"It is disappointing that not only did the road fail, but it placed many drivers in danger and also reportedly damaged a number of vehicles.
"If this happened on the railways, passengers could claim compensation.
"As it has happened on the roads, drivers just have to put up with it."