WASHINGTON — A breakdown of safety management throughout the D.C.-area transit system preceded the Metrorail crash last summer that killed nine people, a federal official said today.

Investigators have said since weeks after the crash that a signaling system's failure to detect a stopped train was the likely cause of the crash. Today, the National Transportation Safety Board chairwoman said the board's investigation has revealed that safety problems in the system went much further.

"Metro was on a collision course long before this accident," Chairwoman Deborah A.P. Hersman said in her opening statements at a meeting on the June 2009 crash. "As our report shows, this was not the first time Metro's safety system was compromised."

Previous accidents, some of which killed employees, foreshadowed the deadly crash.

"Because the necessary preventive measures were not taken, the only question was when would Metro have another accident — and of what magnitude," Hersman said.

The board will hear investigators' findings and vote on the probable cause of the accident. It will also issue recommendations — likely sweeping and costly — on how to avoid similar disasters.