Massachusetts authorities are investigating how a structure built for the embattled Big Dig project became he site of an unauthorized indoor driving range for state troopers.

The Boston Globe reported that a Massachusetts Turnpike Authority spokesman said state police officials confirmed that troopers in a motorcycle unit had set up a net in a room in a Big Dig ventilation building in East Boston near Logan Airport so they could drive golf balls. The police unit has offices in the building for the troopers.

John Cogliano, chairman of the authority, first heard about the driving range Wednesday night in a news report. He contacted the superintendent of the state police, Colonel Mark F. Delaney, Thursday morning, the Globe reported.

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MTA spokesman Jon Carlisle told the newspaper there is no evidence that authority employees swung golf clubs there. State police officials told Cogliano that they had removed the net a couple of weeks ago and are conducting an internal investigation into the matter.

The Big Dig project, which was expected to cost $2 billion when it was designed in the mid-1980s, has been plagued by cost overruns and reluctance by officials to acknowledge them. Earlier this month, state officials disclosed that its final price tag could be close to $15 billion, according to the Globe.