A limited investigation into last week’s derailment of a Silver Line Metro train has found that Metro officials may have known about problems with track in that area since 2009, according to findings released by the National Transportation Safety Board on Wednesday.

NTSB investigators also found that Metro officials continue to violate their own standards for ensuring the safety of the hundreds of thousands of passengers who use the system daily.

For example, Metro’s guidelines require that tracks be inspected twice a week. Records show that Metro workers have been inspecting track, looking for problems that can cause accidents, just once a month. What’s more, the specialized vehicle used to identify track defects is out of service. It is not clear when it broke down.

“Today’s NTSB briefing has, once again, highlighted unacceptable shortcomings in Metro’s safety culture,” said Rep. Gerald E. Connolly (D-Va.) “It is not enough to simply have standards on the books. In this case, Metro had more stringent standards than required by the federal government, but those standards are useless if they are not carried out each and every day and enforced from top to bottom.”

“Today’s revelation from NTSB investigators that Metro had decreased the frequency of inspections, in violation of their own safety standards, on the crossover tracks that led to the July 29th derailment is just one more example of the lack of a safety culture that must be changed,” Rep. Barbara Comstock (R-Va.) said.

Metro officials declined to comment on the NTSB’s findings, saying its own investigation into the derailment is ongoing.

However, transit agency officials told the NTSB that they have changed some procedures related to the safety board’s findings. Crossovers — areas of rail where trains switch tracks — will now be inspected by an automated vehicle instead of visual checks by track walkers, they said. And rail inspections will again take place twice a week, Metro officials said.

The safety board presented its findings to members of Congress from the D.C. region as well as committee staff with oversight of transportation safety.

[Metro says track defect caused derailment]

One person, who was briefed on the contents of the report but is not authorized to speak to the media, said the NTSB findings continue to demonstrate that last week’s derailment — like other recent incidents — could have been prevented.

The latest revelations come on the same day that Metro General Manager Paul J. Wiedefeld met with senior managers and engineers to emphasize the importance of safety. Since coming on board in November, Wiedefeld has made the safety of the nation’s second-busiest subway system his top priority.

[Metro’s GM calls managers in for safety meeting]

In March, after a smoke incident eerily similar to the one that killed a 61-year-old grandmother from Alexandria in January 2015, Wiedefeld called for an unprecedented shutdown of the entire rail system so that emergency inspections could be performed. In June, he launched SafeTrack, an extensive program to rebuild the system.

At Wednesday’s meeting at the Verizon Center, blocks from Metro’s headquarters, Wiedefeld reminded officials they should not hesitate to take sections of track out of service or reduce train speeds if they suspect a problem. As if to underscore that, Wiedefeld sent a memo to Metro staff saying that a train operator who allegedly ran a red signal near the Reagan National Airport station had been fired. Last month, another operator was fired after running a red signal on the Red Line.

The Silver Line train derailed Friday morning about 50 feet from the platform of the East Falls Church station. Approximately 75 passengers were aboard the train; no one was seriously hurt.

NTSB officials said shortly after the derailment, they sent two investigators to the scene to determine whether a formal investigation was needed.

On Monday, Metro officials announced that the derailment was caused by a defect known as “wide gauge,” in which the running rails of a track have spread so far apart it causes the train’s wheels to slip off the rail.

NTSB’s investigators said Metro officials indicated that they were aware of deteriorating track conditions in that area since 2009. It is unclear when Metro workers last inspected that stretch.

They also found that the tracks were 59 inches apart. Metro’s standards require that any section of track with a gauge greater than 57½ inches must be taken out of service. The investigators also found more than 30 feet of track that had no effective cross-ties, parts that help hold rails upright and keep them properly spaced apart — another violation of Metro standards.

The derailment forced the closure of the East Falls Church station from Friday morning until early Monday morning to allow workers to remove the train and repair the track.

The NTSB report also raises questions about the Federal Transit Administration’s oversight of the Metrorail system.

Since taking temporary responsibility for Metro oversight, FTA officials have conducted more than 200 inspections of the rail system and found more than 1,100 instances where Metro officials failed to follow their own safety procedures or protocols.

Even so, the transit agency’s problems have continued. In the last month alone, there have been three instances where train operators ran through red signals.

In some quarters, that has fed doubts about whether FTA has the resources and expertise to ensure Metro’s safety.

Earlier this month, members of the House Committee on Oversight sent a letter to the Government Accountability Office to explore the question of whether the Federal Railroad Administration rather than the FTA should be responsible for oversight of Metro’s rail system.

[Congress requests audit on FTA oversight; SafeTrack repairs]

In a statement issued Wednesday, FTA officials noted they were the first federal agency to respond to Friday’s derailment. They noted that their inspectors also have found “systematic safety deficiencies” in how Metro maintains and repairs rail tracks. FTA officials said a more detailed analysis and a safety directive mandating Metro take certain actions tied to track maintenance and repair will be released in coming months. However, officials declined to say whether they had inspected the area where the derailment occurred.

Faiz Siddiqui contributed to this report.