Google Streetview shows a collection of crosses near this intersection. It seems a family died there some twenty years ago.
The farm residence and trees in the SE corner block the view of approaching traffic. Out here in the prairies, I keep an eye on traffic approaching stop signs to make sure the driver is slowing down for it. I've seen stop signs blown
The truck was pulling a double trailer of peat moss. Perhaps the truck driver blew the sign or perhaps the truck pulled out when bus was far away and the bus driver thought the truck and first trailer would be out of the way, but was not aware of the second trailer until too late.
Photos show that the NB rail crossing sign was swept away by rear trailer, but the WB stop sign and lamppost is still standing.