Doesn't matter if the truck had speed control or not. What matters is that the truck veered onto the center divider, past the shoulder, and totally shredded itself on the grader. Why it veered (inattention, medical emergency, etc.) is the question, and it may never be answered. But if Test Dummy and his band of engineers are asked to look at this, I would like to know what comes of that, even if inconclusive.
They are going to have to send the grader back to the drawing board. It lost a tire in the collision.
I'm wondering why the grader driver was out of the cab. Not that he could've done anything if he had been in it, but there's also another question that needs to be asked: isn't there supposed to be a 'protection' truck following equipment, with the big crash protection barrier on the back of it? I thought those were supposed to be mandatory to prevent collisions like this?
Those rolling crash barriers are only used for roadway and shoulder work. If taken off road, they would likely get stuck. Down in SoCal, graders are often used to deal with earth that is shifting, or even sliding. Preventative 'dressing up' of areas is done to mitigate potential slide damage to roadways. The grader operator has to scope out the earth that needs moving, and where it will be moved to. That requires walking the area and making decisions prior to starting work. He also could have been taking a leak.