Earlier quoted context omitted.
Underrun guards are a good idea but not yet practical for trailers in the US. The reason is that loading dock approaches have far too much variance in ground height, and the empty space under the trailer is essential to have. If guards were in place, they would come into regular contact with the ground and either damage the trailer or the truck would be 'high centered' and stuck, resting on the guards. I suppose the…
I don't know if this excuse holds water. If 28 disparate states with different freight profiles can pull it off, surely the US can too. It's all about will.
The span under the trailer behind the rear drive axle(s) and the forward trailer axle is much longer than you find on European trucks. That means you need a much longer underride guard. You also have to convince trucking company execs that all that extra weight is a good thing even though they know it's cheaper to pay the occasional settlement after a gruesome accident.
Also, putting the trailer axles further forward to shorten the gap is not possible until Indiana changes their minimum axle length regulation (40 feet trailer kingpin to rear axle centerline) because I believe that while they are the only state to have such a rule, you can't do much interstate commerce with a fleet of trucks and avoid travelling through that state with its central location.
Trucking in the US is massively regulated and bureaucratic and you are going to need a lot more than will to get it to change. I'd love to see safer trucks too but I am not optimistic about seeing underride guards in the US anytime soon.