ANNAPOLIS, Md. – Thomas Osborne, executive secretary of the Maryland Transportation Authority, has resigned amidst a probe into why more than half of the resurfacing work on the Chesapeake Bay Bridge has to be redone.

The cost of fixing the work on the westbound span will add at least $7 million to the project’s $60 million cost, Osborne said last month. He said Monday he is resigning so the public would have full confidence in an open and objective review of what went wrong, according to a news release from the agency.

Deputy Executive Secretary Daniel McMullen will take over Osborne’s job overseeing the day-to-day operations of the authority, while officials look for a new executive secretary.

A task force is trying to uncover how the mistakes in the bridge work happened and who is responsible. They’re looking into the contract the state signed with Cianbro Corporation, which is based in Pittsfield, Maine.

Depending on what the task force uncovers, the issue of who pays for the additional work could end up in court, Transportation Secretary Robert Flanagan has said.

Flanagan said cracks in the concrete began appearing last year after the contractor used a resurfacing method intended to speed the project by allowing work to continue in cold weather.

Cianbro has issued a statement saying it performed all work according to the specifications of the contract.

Fixing the problem will force more lane closings than previously expected – mostly in spring and fall next year. The peak summer season will not be affected, officials have said.

The resurfacing on the westbound bridge involves replacing the bridge deck for the first time since the newer part of the 4.3-mile Bay Bridge, formally called the William Preston Lane Jr. Memorial Bridge, opened in 1973. The older eastbound span, which opened in 1952, was resurfaced from 1987 to 1989.