The C4 stopped on the front stretch. The car right in front of Voigt swerved immediately to miss the C4 and Voigt couldn't avoid the stopped car.
They were coming thru there at full speed.
I think the C4 was only stopping to draw a caution for a flat tire. He ended up with a lot more than a flat though after that. It wasn't the best place to stop to draw a caution.