Jose Bonilla climbs onto the track as work continues on the Washington Metropolitan Area Transit Authority Silver Line project in Tysons Corner. A 44-page report by the Department of Transportation’s inspector general focuses on what actions the FTA has taken to address safety concerns first raised in 2009. (Nikki Kahn/The Washington Post)

The Federal Transit Administration’s oversight of the Silver Line rail project must be more responsive to safety issues and more aggressive in its monitoring of costs and scheduling, according to a federal audit released last week .

The 44-page report by the Department of Transportation’s inspector general focuses on what actions the FTA has taken to address safety concerns first raised in 2009. It also recommends that the agency use its oversight role to ensure that costs are more closely monitored.

The 23-mile Silver Line rail project is being built by the Metropolitan Washington Airports Authority and is one of the nation’s largest infrastructure projects. But the project has been dogged by political battles over its price tag, disputes over funding, and concerns about whether MWAA and other parties involved in its construction are doing enough to ensure passenger safety.

Questions surrounding bridge safety surfaced in 2009, after the then-chief bridge manager for the project raised concerns about whether enough testing had been done on dozens of steel pilings that would support the bridge to carry trains and passengers over Interstate 66. His efforts were rebuffed until reports of his concerns were reported in The Washington Post.

Federal officials intervened and tests were conducted. But the inspector general notes in its new report that concerns remain.

The report says that although proper tests on the pilings were completed, the FTA was slow to follow up on other issues raised by the inspector general’s office in 2011. It wasn’t until June that the agency provided a response.

Ultimately, the report says, the inspector general’s concerns were addressed. But “the extended process in reaching this point supports the need for the FTA’s plan to assess elements of its oversight processes,” the report says.

The report says that the FTA also has agreed to provide assurances that structures will meet the 50-year service life called for in FTA guidelines. The concern about the structure’s life span is that stray electrical currents could corrode the piles closest to the rail tracks. The FTA said in June that it had directed MWAA to conduct additional testing.

The FTA is “committed to the safety of the Dulles Corridor Metrorail project and has taken extra steps to verify that the agency’s oversight process is effective,’’ spokesman Brian Farber said in a written statement.

Proponents of the $6 billion rail extension say it will carry as many as 60,000 riders a day, many from their homes in Reston, Herndon and the outer suburbs to jobs in Tysons Corner and the District. It will also provide the region with a rail link to Dulles International Airport.

The first phase of the project, which will run from East Falls Church to Wiehle Avenue in Reston, is expected to be completed next year. A second phase will extend into Loudoun County.

In addition to the safety issues raised in the audit, the inspector general recommended that the FTA should be a more effective watchdog in ensuring that the deadlines are met and that issues and disagreements between project partners are promptly addressed. As an example, it cited concerns about the delivery of rail cars to be used when the first portion of the Silver Line opens next year.

The FTA was aware that there would be a delay in the delivery of rail cars, but it had not, as of June, accepted an updated plan from the Washington Metropolitan Area Transit Authority, which is providing cars for the new line, on how it would address the issue.

“FTA will continue to enforce rigorous, timely oversight of this complex and nationally significant project every step of the way, to assure the public that the new rail service will be safe and reliable for generations to come,” Farber said.