BOSTON (AP) - The state highway administrator says it will cost $54 million to replace all the light fixtures in the Big Dig tunnels because of design or manufacturing defects that have led to dangerous corrosion that could result in them falling onto traffic.

Frank DePaola told the Massachusetts Department of Transportation directors Wednesday that since a light fixture fell onto the road in the Thomas P. O’Neill Jr. Tunnel in February 2011, engineers have temporarily reinforced the 8-foot light fixtures in the 7.5 mile tunnel system with plastic ties.

DePaola says a complete replacement is the best solution.

The Boston Globe reports that the new fixtures will use energy-efficient LED lights that could save $2.5 million a year in energy costs.

The replacement project is expected to begin next year.

The Big Dig, a megaproject in Boston that rerouted the Central Artery (Interstate 93), through the heart of the city, into a 3.5-mile (5.6-km) tunnel, was concluded on December 31, 2007 at a cost of over 14.6 billion. Originally scheduled to be completed by 1998, the project was plagued by escalating costs, scheduling overruns, leaks, design flaws, charges of poor execution and use of substandard materials, criminal arrests, and even four deaths.

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