Thanks! Given the paintings on the ground, and the shape of the curbs, I'd say he was heading north, not south, and possibly turned right from the left turn lane. So, putting my speculation hat on (it's made of tin foil!
) I'd say the van wanted to go wide, crossed into the left turn lane in order to make the right hand swing. The crossover following him probably thought he had has signals reversed (if we was using any) and tried to go straight through thinking the van meant to go left being in a left turn lane.
Ok, I feel better now. Still, never seen an intersection with a stop line only for the turning lane like that.