The Big Dig's project labor agreement was negotiated in 1989 and it guaranteed union members exclusive rights to work on the Big Dig in exchange for the union's commitment not to strike for the duration of the project. To date, there have been no work stoppages on the Big Dig.

"They're on schedule," Joe Nigro, president of the Boston Building trades Council, tells GlobeSt.com. "We're not trying to hold up the Central Artery. They have the same question in mind that we do, whether they can do this."

At $440 million, the project being put out to bid--to dismantle the elevated Central Artery and renovate the Dewey Square Tunnel--is reportedly one of the largest of the 19 remaining on the Big Dig. If the project labor agreement is broken on this contract, union members will ostensibly be free to strike.