Probably everyone is getting bored by this, but it still nags at me. If he crashed through the gates, it would be your basic asleep-at-the-wheel. But he veered around the gates.

It's not surprising that he can't remember what happened; people subject to trauma frequently cannot. Football players who get a concussion on a play can't remember the play.

Maybe this fits the facts: He is cruising along half asleep. His visual apparatus sees the train but his cognitive apparatus does not react. He finally comes to alertness at the last minute, just as he is about to hit the gates. He slams on the brakes and veers around the gates, so as not to hit them; but he is unable to stop before he hits the train.

If the police find skid marks at the scene, it might be possible to test this theory.