The Federal Transit Administration is struggling to hire and retain enough qualified people to oversee the safety of Metro and the network of state-based agencies that monitor many of the nation’s subway and light-rail systems, according to a new report released Friday.

The FTA, which took responsibility for the safety of Metro’s rail system a year ago, is still working to develop policies for such supervision, and it does not yet have a clear plan for transitioning back to a state-based oversight system, according to the audit by the U.S. Department of Transportation’s inspector general.

Coming a year after the FTA assumed oversight of safety at Metro, the report could raise new questions about whether federal safety oversight will be effective, given a lack of data and specific standards. It may also renew debate over whether U.S. Transportation Secretary Anthony Foxx made the right decision in putting the FTA in charge of Metrorail safety.

The National Transportation Safety Board last year urged Foxx to assign the Federal Railroad Administration to oversee safety in the Metrorail system.

The inspector general did not take a position in that debate.

“Our review did not assess which Operating Administration — FTA or FRA — was better suited to assume direct oversight” of the Washington Metropolitan Area Transit Authority, the report’s authors wrote, noting that Congress has directed the Government Accountability Office to review that question.

The 22-page report builds on previous work by the inspector general examining the FTA’s ability to move from a grant-making function to focusing additionally on ensuring passenger safety of the nation’s subway and light-rail systems.

The report offered seven recommendations for creating a system that would hold transit agencies accountable for the safety of their millions of passengers, such as providing clear guidance for when the federal government would step in to provide direct oversight.

In a letter responding to the audit, FTA acting administrator Carolyn Flowers said her agency concurred with the inspector general’s findings and would implement the recommendations by the end of 2017. An agency spokeswoman said Friday that there would be no additional comment.

The FTA was still building its safety oversight team when Foxx announced in October 2015 that the federal government would take direct responsibility for ensuring the safety of Metro’s rail system. The inspector general’s report said the additional responsibilities have strained the FTA’s resources, forcing the agency to bring in experts from other agencies within the Department of Transportation as well as consultants.

Metro had experienced several disturbing events when Foxx decided to intervene. In a January 2015 smoke incident, one passenger died and scores were sickened when their train was stuck in a tunnel that filled with smoke generated by an electrical fault on the tracks. That was followed by a train derailment that August. There were no serious injuries, but the subsequent investigation found that Metro officials had known for a month that the section of track where the derailment occurred was damaged but failed to fix it.

Foxx and others, including the NTSB, concluded that the Tri-State Oversight Committee (TOC), a board that included representatives from the District, Maryland and Virginia charged with oversight of Metro safety, was ineffective. But there were different views on how to address the TOC’s shortcomings.

In an “urgent” recommendation released in September 2015, Christopher A. Hart, the chairman of the NTSB, requested that Foxx assign oversight responsibilities to the Federal Railroad Administration, a bigger agency with greater enforcement authority. But Foxx said he did not agree that was “the wisest or fastest way to bring about the necessary safety improvements” at Metro. He promised a robust program, noting that the FTA would draw on the expertise of other agencies within DOT, including the FRA.

Foxx is the first secretary of transportation to take that step under authority given to him by Congress in 2012. That legislation gave the secretary the ability to intervene when it has been determined that state-based oversight has failed.

In December, concern about the FTA’s ability to take on that role led the DOT’s inspector general to announce that it would conduct a follow-up audit of the FTA’s ability to take on the additional responsibilities of Metro.

In the letter announcing the audit, Mitchell Behm, assistant inspector general for surface transportation audits, noted that even with the FTA’s additional oversight powers, the agency still might “face significant challenges in carrying out these new responsibilities.”

In a 2012 audit, the inspector general’s office had raised concerns about whether the FTA was equipped to take on the additional role of safety oversight. That audit was completed in anticipation of the FTA having expanded responsibilities for safety under legislation that would later be passed by Congress. The review found gaps in data collection and in the level of staffing devoted to safety oversight. The audit also recommended that the FTA establish national safety standards to bring uniformity to its oversight efforts. States would still be free to create their own standards but would be required to meet baseline requirements for safety.

FTA officials said they have since expanded staffing and had begun to address concerns about the quality and type of data the FTA collects. The inspector general acknowledged those efforts in the report released Friday.

But in this most recent audit, it is clear that the inspector general remains concerned that the FTA has put only voluntary standards in place.

A lack of mandatory standards coupled with a lack of data could prevent the FTA from providing “pro-active” safety oversight, the report said.

“Unless FTA addresses these challenges, it may be unable to meet the Federal transit safety goals and objectives that are central to its enhanced safety oversight authority,” the report said.

The report’s authors also noted that NTSB staffers agreed with their concerns that making safety standards voluntary “diminishes their effectiveness as an oversight tool.”

The other recommendations include:

●Finalize procedures and policies for when the FTA takes control of safety oversight of a transit system and communicate those policies internally and to the rail transit industry.

●Finalize procedures for returning safety oversight to state-based agencies.

●Finalize a plan to create a data-driven, risk-based oversight system.

●Ensure that state safety organizations are audited regularly.

●Finalize a plan for updating the National Safety Plan to deal with major emergencies.