That’s a favourite game - speculation as to what happened !
The damage you refer to is relatively minor and may well have been caused by another vehicle hitting it, the reaction of the driver probably then put the vehicle ultimately on its side unfortunately, but that’s reflex actions for you ! Unlikely that the LGV struck anything itself to cause that damage as the t-bar looks undamaged.
Got pictures of it being recovered but ain’t got a clue how to post them on here !
If I see a PRDC driver later I’ll see if he/she knows ‘owt !