BOSTON -- Massachusetts Attorney General Martha Coakley has moved closer to settling with two of the three companies held most responsible for failures in parts of Boston's "Big Dig" road tunnel.

Reports today suggest the project's top managers, Bechtel Corp. and Parsons Brinckerhoff, will settle with Coakley for over $300 million and escape criminal charges under the deal. Powers Fasteners is the only company to face criminal indictment over the failures, which included leaks and ceiling falls.

Coakley has been heavily criticized for spending almost $1 million on special prosecutor Paul Ware Jr. to bring charges against Powers Fasteners, LNL reported two months ago. Powers pleaded not guilty last year to manslaughter over the motorist's death in July 2006.

The company recently announced it would pay the family of the motorist, Milena Del Valle, $6 million in compensation. Powers Fasteners made the epoxy bolt system used in the ceiling of the I-90 tunnel, part of which collapsed and killed Del Valle.

Bechtel and Parsons Brinckerhoff avoided criminal prosecution by remaining in settlement negotiations with the state, although reaching agreement has been frustrating.