As expected, the NTSB concluded that the collision occurred because Metro's automatic signal system failed to detect the presence of the stopped train. The operator of the approaching train was told to continue traveling at 55 mph. She pulled the emergency brake, but the train was still traveling at more than 40 mph at the moment of the collision.
More broadly, the NTSB said Metro ignored repeated warning signs and fostered a culture of indifference to chronic safety issues.
The agency was warned about deficiencies in its safety department for 15 years before the crash, NTSB chairwoman Deborah Hersman said.
"If they don't listen this time, I'm not sure what else can be done here," Hershman said. "There's got to be some action; there's got to be some change. There needs to be better oversight."
The NTSB faulted Metro's board of directors for failing to actively monitor safety issues. The track signaling system failed to recognize trains 3,000 times a week, but the issue was deemed a minor nuisance, the NTSB said.
In her opening remarks, Hersman said the Fort Totten station crash was not the first time Metro's safety system was compromised. Previous accidents, some of which killed employees, foreshadowed the deadlier crash, she said.
"Because the necessary preventive measures were not taken, the only question was when would Metro have another accident - and of what magnitude," Hersman said.
--- Associated Press writers Matthew Barakat, Lauren Sausser, Jessica Gresko and Ben Nuckols in Washington, and Brian Witte in Annapolis, Md., contributed to this report.