The Northwood sinkhole measured a whopping six feet deep and six feet across, experts say.
The yawning void that opened in Pinner Road this morning is baffling Hillingdon Council engineers, who along with police raced to the spot.
Council workers have been busy all day filling in the chasm that opened up without warning on a busy Northwood street close to the Royal Mail sorting office, causing traffic chaos in the area.
The council’s highways team is planning to remove temporary traffic lights and fully reopen Pinner Road at 6pm, and the road has been resurfaced.
Meanwhile traffic is being diverted down Addison Way.
The question remains: what caused a decent sized piece of road to suddenly collapse?
Earlier today (Friday), Hillingdon Council said it thought the cause might have been a collapsed Thames Water drain cover, but that has been discounted by Nigel Dicker, the council’s deputy director of public safety and environment.
Sinkholes that have appeared around the UK in recent months have been attributed to old mine workings or quarries and the effects of the torrential winter rain.
It has been a busy couple of days in Northwood: a crane collapsed on a building site in Maxwell Road, forcing a family to leave their home.
What caused the Pinner Road sinkhole? Leave your theory below.