Federal safety regulators slammed both D.C.’s Metro system and the U.S. Department of Transportation on Tuesday for their responses to dangerous flaws in the region’s rail network, including a January 2015 fire near L’Enfant Plaza that killed a passenger with smoke inhalation.The Washington Metropolitan Area Transit Authority has made “little or no progress” in making safety a priority despite a long serious of breakdowns and accidents, National Transportation Safety Board Chairman Christopher Hart said during a hearing on the 2015 fatality.