Bechtel Corp. and Parsons Brinckerhoff Inc., the private-sector managers of the construction project, were named in the suit filed in Suffolk Superior Court that seeks $146 million -- about 1 percent of the final cost of the project.
Court documents state, "The defendants utilized their superior knowledge and expertise to conceal project cost overruns in order to continue, for their own improper benefit and by improper means, the highly lucrative contracts with the Commonwealth (of Massachusetts)."
Bechtel/Parsons Brinckerhoff issued a statement saying the lawsuit "is without merit."
The state contends that if accurate estimates had been submitted in 1994, officials may have changed plans to proceed with the project, the Boston Globe reported. The project -- called the Big Dig -- began in 1985. The private contractors in 1994 said the project could be completed for about $8 billion, but had earlier said the cost would be about double the $7.7 billion then allocated for the project.