from what i understood it is a bridge so there is a slight slope and a small curve. so he was going full speed and probably when he seen them started to break and used the horn. for sure if he wanted to run anyone over he could just turn left or right and kill a lot of them. the slow moving video was after the initial stop, when they tried to get him out of the truck, so he started moving for maybe 50m at slow pace, probably thinking they will give up. looks like at one moment there were 7-8 people hanging on the truck so he just stopped to not run over someone, because there was no other reason for him to stop again.
no idea why he was on that road, but for sure did not want to kill anybody.