Unexplained , intermittent failures persist despite repairs , Metro official says . NTSB recalls loud bang , `` accordion-like '' collapse of floor , screams . Delegate chides Metro for making high-cost , `` impossible '' recommendations . Nine people killed , scores injured in June 22 crash near Fort Totten Red Line 's station .
Unexplained , intermittent failures persist despite repairs , Metro official says . Passenger recalls loud bang , `` accordion-like '' collapse of floor , screams . Delegate chides NTSB for making high-cost , `` impossible '' recommendations . 9 people killed , scores injured in June 22 crash near Red Line 's Fort Totten station .