The Maryland Transportation Authority has begun work on a $43 million project to shore up the foundation of the nearly 50-year-old Millard E. Tydings Memorial Bridge on Interstate 95, where the flow of the Susquehanna River has eroded some of the piers that support the span.

The construction work on the bridge, part of the toll stretch of I-95 called the John F. Kennedy Memorial Highway, is not expected to seriously disturb bridge and boat traffic, and no lane closings are anticipated.

Ten of the bridge's 13 piers will be rehabilitated. Those piers, which stand in the water, are subjected to a form of damage known as "scour" caused by the river's currents.

The work is expected to be complete by late 2013, according to the authority. The project is financed by revenue from the state's toll facilities.

The authority said in 2009 that its inspectors had found "advanced deterioration" in the underwater structures that support the Tydings Bridge. Deterioration was also found at the 71-year-old Thomas J. Hatem Memorial Bridge, which spans the Susquehanna just downstream from I-95 on U.S. 40.

The cost of the Hatem Bridge project, which is expected to enter the construction phase by spring 2012, is estimated at $54 million.

The rehabilitation work will involve placing dams around each of the underwater piers and pumping out water to expose the structures. Reinforced concrete encasements will then be built around the existing piers.

michael.dresser@baltsun.com