The National Transportation Safety Board has concluded that a faulty electronic circuit caused the 2009 Metro crash in Washington that killed nine people and injured 52 others.
More broadly, the NTSB at a hearing Tuesday blamed an "anemic safety culture" at Metro for ignoring repeated warning signs and fostering a culture of indifference to chronic safety issues.
Eight passengers and a train operator were killed in June 2009 when a Metrorail train rear-ended a second train stopped near a station.
The collision occurred because Metro's automatic signal system failed to detect the presence of a stopped train just ahead of the station.
Investigators had said previously the faulty equipment was likely the cause, but Tuesday's finding represents the conclusion of a lengthy federal investigation.
The NTSB doesn't have the power to enforce its recommendations, but a failure by Metro to comply with them could cause federal and state governments to curtail the transit agency's funding. The board wields similar influence over transit agencies around the country.
Metro has been working to comply with recommendations the NTSB made in the months after the crash and announced last week that it is putting aside $30 million over three years to carry out whatever recommendations come out of Tuesday's meeting. That amount represents a fraction of what Metro is spending on overall upgrades.
This was not Metro's only deadly accident in recent years. Two Metro workers were crushed to death on tracks in January when a maintenance truck backed into them. Last year, two more Metro workers were killed in separate incidents. There was also a close call in December when safety inspectors were nearly hit.
Carolyn Jenkins of Washington, whose daughter Veronica Dubose was killed in the crash, said she came to Tuesday's hearing seeking closure. Jenkins now cares for her two grandchildren, ages 2 and 8.
"I want to hear what really happened. I want to hear the truth," Jenkins said. "I want everyone to stop pointing fingers."