In the following government document NHTSA uses Cost-benefit Analysis to argue that underride guards cannot be cost effective for single unit trucks. They argue that injuries can be added together to equal fatalities. They ignore world accepted safety philosophy of Vision Zero for all world road safety efforts. They ignore the Constitutional right of citizens to not be deliberately killed by the ruling elites in society. They ignore the rule of democracy over plutocracy. They maintain in their reasoning that life and freedom of the masses may be purchased.
Original Document at http://www.regulations.gov/#!documentDetail;D=NHTSA-2015-0070-0001