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The Boston Globe

Metro

MBTA to inspect system’s third rails

MBTA inspectors planned to begin scrutinizing the third rails of the T’s subway tracks Thursday night after the end of T service in an effort to prevent fractures similar to those responsible for widespread commuting delays this week.

Two cracks on Red Line rails — one on Tuesday night, the other on Wednesday morning, both at JFK/UMass Station — prompted Beverly A. Scott, general manager of the Massachusett Bay Transportation Authority, to call for a widespread audit of the third rails on the Red, Orange, and Blue lines.

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The third rail delivers electric power to the trains. The cracks are believed to have been caused by cold weather, which caused the metal to contract and fracture at the points where the rails were welded together. A crack in the rail is not dangerous — without power, trains simply come to a stop — but T officials intend to inspect the welding on third rails in the system to ensure that future cold spells do not cause the same disruptions.

T officials are awaiting a formal plan that will outline the scope of the inspections, but staff decided to get a jump on the task with the first round of inspections Thursday night.

“We want to get it done as soon as possible,” said T spokeswoman Kelly Smith.

Martine Powers can be reached at martine.powers@globe.com. Follow her on Twitter @martinepowers.

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