Report urges better oversight of Big Dig by federal officials

The report shows that the US Department of Transportation’s inspector general believes that Massachusetts has done a good job of implementing the safety improvements recommended in a “stem-to-stern review’’ that followed the accident.

But it also says the Highway Administration needs to do a better job in three areas: ensuring the safety of ceiling anchors in the Ted Williams Tunnel, improving the Big Dig’s preparedness for a fire, and making sure calculations for the safety of concrete viaducts are accurate.

The inspector general’s office said in the report that it is making a series of recommendations to the Highway Administration “to strengthen its oversight of the Commonwealth’s actions to address unresolved safety risks.’’

In its response to a draft of the report, the Highway Administration disagreed with the conclusion “that its oversight approach has shortcomings,’’ the report said.

And in a follow-up statement, it added: “The Federal Highway Administration will continue to ensure the safety of tunnels, highways, and bridges across the country. We are confident that all the pressing safety issues related to the Central Artery Tunnel have been resolved.’’

The report pointed out that testing showed persistent problems with evacuation procedures, especially for the mobility impaired, in a potential truck fire. On that item, the inspector general targeted the state for action. The Commonwealth should use these findings to safeguard motorists in case of a tunnel fire,’’ the report said.

The Big Dig involved replacing the elevated Central Artery through Boston, Interstate 93, with a series of tunnels. It also built a third connection to Logan International Airport, the Ted Williams Tunnel.

The project took a tragic turn in July 2006, when several ceiling panels in one tunnel broke free, crushing a car and killing Milena del Valle, 38, of Boston.