The tunnel bore in Seattle is a good example of why low-bid contacts, even negotiated ones, do not serve the public well.
Public works contracts are typically awarded on a low-bid basis as long as they meet qualifications and specs. Major high-risk projects involve meeting many requirements that are not necessarily easily identified. When a low-bid contract is let, all of these unidentified problems are only outlined superficially throughout the items within the bid and may be paid for through negotiated changed conditions.
Low-bid contractors will try to protect themselves through high item cost rather than spending the time trying to identify what they may be faced with. This leads to attorneys, mediation and court costs. A contract of high risk that is let with good parameters, requiring the contractor to assume the risk for design and a successful completion, is far more cost-effective for the tax payers.
The state Department of Transportation does not have the qualified personnel, is handicapped politically and feels it must utilize low bid only for this type of project. Contracting of this nature is very risky, and the contractor should receive a reasonable profit. A good example of success is the second Narrows Bridge, which utilized good contractors with the knowledge required.