Commuters on the M25 clockwise faced delays of more than an hour following a three-vehicle crash on the M25 on Thursday (April 13).
One person was taken to Watford General Hospital with "what is believed to have been minor injuries" according to East of England Ambulance Service.
The crash, between Junctions 18 (Chorleywood) and 19 (Watford), lead to two of the four lanes closing and tailbacks of more than nine miles, stretching back to Junction 16 M40 (Uxbridge).
The incident took place at around 7.40am and Hertfordshire Fire and Rescue services attended the scene to free people trapped in their vehicles, Hertfordshie Police said.
Ambulances and the Metropolitan Police also attended the crash.
Traffic built up as far back as Junction 16 of the M25, often at a standstill, with all lanes reopening shortly after 9.30pm.
Traffic was still heavy at around 10.15am but was beginning to ease.
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