Boston ? Contractors will pay more than $450 million to settle the state’s lawsuit over a fatal tunnel collapse and to cover the costs of leaks and design flaws in the Big Dig, officials said Wednesday.

Bechtel/Parsons Brinckerhoff, the consortium that oversaw design and construction of the nation’s costliest and most complex highway project, has agreed to pay $407 million, U.S. Attorney Michael Sullivan said in announcing the deal. Several smaller companies will pay about $51 million collectively.

Under the settlement, Bechtel/Parsons Brinckerhoff will not face criminal charges in the deadly Interstate 90 tunnel ceiling collapse in July 2006.

Milena Del Valle, 39, of Boston, was crushed by 26 tons of concrete as she and her husband drove to Logan International Airport.