I would have to say (as a one time HazMat type and as a retired working engineer in the alternative-green,renewable energy and environmental field; and as a HazMat instructor for NGO volunteer emergency responders)
KISS = "Keep It Simple Stupid"
I have to disagree with the assumption that terrorists will drive around looking for random tank cars or tank trucks as "Targets of Opportunity." They plan, they study, they do their home work. They probably know the difference between a liquid nitrogen tanker and a liquefied natural gas tanker.
Some would argue that this proposal is just to keep environmental groups in ignorance of what is being manufactured and stored in their communities or being transported through their communities. Environmental activists have already made this argument. There might be a grain of truth in this (remember Bhopal and Donora). Except that even the "industry" opposed this proposal.
SEMPER PARATUS
SAINT FLORIAN PROTECT ME AS I WALK INTO HARM'S WAY TO AID THE DISTRESSED<
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