Firefighters and other emergency personnel swarm around the wreckage of two trains that collided on the Red Line in 2009. (Hans Charles/For The Washington Post)

A federal judge ordered the unsealing of settlement agreements in lawsuits involving a deadly Metrorail crash that killed nine on June 22, 2009 — a move that will lift the secrecy the transit agency has long tried to put on the financial impact of the accident.

The order is in response to a motion filed by The Washington Post seeking access to the settlement agreements and other documents filed under seal. For more than a year, The Post has been engaged in a battle with Metro for access to the amounts, and the transit agency has opposed the disclosure of the information at every turn.

The crash, the deadliest in Metro’s history, killed the train operator and eight passengers and injured at least 80 others when two trains collided at Fort Totten on Metro’s Red Line. The accident led to damning revelations about the system’s safety practices and a number of recommendations for improvements from the National Transportation Safety Board.

Metro has said it settled all lawsuits filed against the transit agency by the families of the nine people killed, but it has steadfastly refused to reveal the dollar amounts of the settlements, citing confidentiality and other reasons.

U.S. District Court Judge Reggie B. Walton said in a 23-page opinion that was released Thursday that the settlements, subject to certain redactions, and other documents related to confidential mediations should be unsealed.

Walton called the Fort Totten crash “a matter of significant public concern” and he wrote that “because [Metro] is a governmental entity, its presence in this litigation enhances the need for public access to the judicial records.”

“And the fact that some of the sealed records reveal how [Metro] utilized taxpayer funds in settling lawsuits further strengthens the public’s stake in their release,” Walton said.

The settlement documents, Walton wrote, “do not shed much light (if any) on the circumstances of the train collision itself,” but “their disclosure would, at the least, cause an ‘incremental gain in public understanding of an immensely important historical occurrence.’ ”

Because some of the lawsuits involve children whose parents were killed in the accident, the settlements will be subject to redactions for names, birth dates and private medical information, according to Walton’s order.

The court’s order won’t take effect for 14 days to allow Metro and the other defendants in the case who made the subway cars and other parts involved in the accident an opportunity to appeal.

Metro spokesman Dan Stessel said Friday afternoon in an e-mail, “We are reviewing the decision.”

Details of the settlement amounts related to the crash has been something Metro has tried to keep from the public. The cases that have been litigated are likely to involve large payouts and are likely to provide a clearer understanding of the accident’s financial hit on Metro and its insurers.

In his order, Walton cites former Supreme Court justice Louis Brandeis on the importance of transparency: “‘[s]unlight is . . . the best of disinfectants.’”

Metro waited nearly a year to respond to a public-records request by The Post, and when it did, in February, it provided little information. Citing exemptions in its public-records policy and a gag order by the judge, Metro said it would not release information about the cases that had gone to litigation.

The Post submitted an administrative appeal to Metro, asking it to reverse its decision to withhold the information. Metro had said it would not act on the administrative appeal until Walton made a decision on The Post’s motion.

This year, Metro did disclose that it had paid a total of $1.6 million to settle 84 claims that did not go to litigation and involved more minor injuries. The 84 payouts, through Metro’s Office of Third Party Claims, ranged from $333 to $150,000.

Staff writer Ann Marimow contributed to this report.