A pair of train derailments in 2012 that killed two people in Maryland and triggered a fiery explosion in Ohio exposed an unsettling truth: No rules govern when rail becomes too worn down to be used for hauling hazardous chemicals, freight and other products.

A pair of train derailments in 2012 that killed two people in Maryland and triggered a fiery explosion in Ohio exposed an unsettling truth: No rules govern when rail becomes too worn down to be used for hauling hazardous chemicals, freight and other products.

The accidents spurred moves by U.S. officials to establish universal standards for when such steel gets replaced. Interviews by The Associated Press found that resistance from railroads scuttled the attempt.

Now, after a recent oil train explosion in West Virginia was linked to worn rails, Federal Railroad Administrator Sarah Feinberg says the gap in safety regulations needs to be addressed as soon as possible.

Industry supporters argue that the major freight railroads are best positioned to know when rails need replacement.