Looking at how the rails have been deformed, the vehicle looks to have been travelling from Forest Hill and so approaching the bend.
The road here is perfectly straight to this point so this is very odd.
It almost as if they fell asleep at the wheel and just drifted left.
There wasnt any skid marks either which supports this view.
The way the barrier has buckled, you would hope that it absorbed most of the impact and brought the car to an orderly halt. The driver hopefully lived.
So from what we know, a vote of thanks to the person who had the foresight to place these crash barriers along this stretch. And lets have more of them.