Truck driver here, and I'm wondering this, too. Passed the wreck in the early hours, assuming they got on at 286 that is such a clearly-laid out exit. They were on it for miles, too. I suspect we will be hearing a lot more about this one.

Most effective answer to still allow box trucks would be a laser-triggered traffic light. They have these in a couple of places, Lincoln Tunnel in NYC springs to mind. Set it at, say, 9' high. Any vehicle over 9' tall sets off the traffic light, and the big fuck-off flashing red lights on a sign that says road unsuitable for tractor trailers, tight turns and rocks, $5,000 fine, turn around here, call xxx-xxx-xxxx if you need assistance. Box trucks can then proceed.

Wouldn't surprise me if this is a factor. This is a huge problem, towns want the trucks out (understand where they are coming from) so put up signs. Often - especially on state routes - there really isn't anything stopping the trucks and it is a safer and easier path than diverting.