Traffic on the Bay and Key bridges will be temporarily stopped Wednesday afternoon as tugboats push a cargo ship carrying four massive cranes beneath the spans on the way to the port of Baltimore, the Maryland Transportation Authority said Monday.

Coast Guard and state transportation officials were concerned that motorists would become distracted by the sight of the 14-story-tall cranes approaching the bridges and stop to gawk or cause an accident. The cranes stand 178 feet high. The Bay Bridge clearance is 182 feet and the Key Bridge's is 185 feet, according to the National Oceanic and Atmospheric Administration.

The Bay Bridge will be closed for about 40 minutes, beginning at 1:15 p.m. The Key Bridge will be closed for about 20 minutes at 3:15 p.m. The times could change, depending on the speed of the cargo ship, authorities said.

The $40 million cranes will be unloaded at Seagirt Marine Terminal and assembled. They will be able to handle the largest ships in the world, which are expected to use the newly widened Panama Canal once that project is complete in 2014.

Transportation authority officials say they will delay the start of the summer-long Baltimore Harbor steel bridge repair project until Wednesday evening because the Key Bridge is one of the alternate routes for commuters.

candy.thomson@baltsun.com

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