An elderly woman who fell asleep while driving and crashed into a roadside drain was rescued by passing motorists.

Dashcam footage shows the sedan plunging into the ditch with water before other drivers pulled over to the side to help in Bangkok, Thailand.

Good Samaritans ran over to the car to check with one of them diving into the neck-deep water to retrieve the old woman who was trapped inside.

Other onlookers helped pull the car to the side so that the driver's side of the door could be opened.

Chanpong Boonuthit, who is a local news reporter, said: ‘I brought my wife and pet dogs for a meal and was driving home when we saw a car veer off into the drain.

‘We stopped and ran to help. The car was sliding deeper into the water so I jumped and rescued the elderly woman.'

The elderly woman said: ‘I was driving alone to the market. I fainted on the steering wheek and woke up my car had already overturned and someone was rescuing me.'

The driver was injured but refused to go to the hospital. Her car was towed to a service centre afterwards.