Police are trying to determine who was driving a car hit when it became bogged on train tracks at Herne Hill overnight and was hit by a freight train.
Several people tried unsuccessfully to move the car about 11.30pm.
A freight train was unable to stop and smashed into the car, causing substantial damage to the vehicle, the train, boom gates and warning light.
Police spoke to a woman who claimed to be the driver.
She was not injured and was taken to a police station and failed a breath test.
Police are yet to confirm she was the driver of the vehicle at the time it became bogged.