In July, the Department of Transportation (DOT) first proposed measures meant to end fiery train accidents of trains carrying oil from North Dakota across the U.S. Tank cars carrying flammable gas would be forced to move at slower speeds under the plan. But the failure to address vapor pressure, a measure of how much volatile gas is contained, is a major omission cited by critics. Officials have studied vapor pressure since July 2013, when a runaway oil train derailed in the Quebec village of Lac-Megantic, killing 47 people in a fireball that shocked many with its explosiveness.
Until recently, official findings on vapor pressure were in line with industry-funded studies--that North Dakota fuel is similar to other light crude oil deemed safe to move in standard tank cars. However, DOT said recently that it did not properly handle prior samples and that a precision device called a floating piston cylinder is needed to reliably detect vapor pressure dangers. On that admission alone, officials want it removed from train cars.
A Reuters article says that "responses to the DOT's plan are due by Sept. 30, and so far more than 100 comments have been received. Typically in a contentious rulemaking major stakeholders submit their views just before the deadline."