The Big Dig scheme routed the I-93 under the city of Boston. The project suffered a catalogue of problems, culminating with the death of 38-year-old Milena Del Valle when a section of ceiling collapsed onto traffic.
Under the terms of the agreement, Bechtel will contribute $352M (£180m), and Parsons Brinckerhoff contribute $47.2M (£24M), which includes cash intended for future repairs and nonroutine maintenance of the Central Artery/Tunnel.
Both Bechtel and Parsons Brinckerhoff will take specific actions to enhance their existing training, compliance, and quality assurance programs in order to improve long-term performance and ensure that future work benefits from lessons learned during the Central Artery/Tunnel project. The agreement also provides remedies in the unlikely event of a future major incident for which Bechtel/Parsons Brinckerhoff is liable.
"We have always said that we take responsibility for our work," said chairman of the Bechtel/Parsons Brinckerhoff (B/PB) joint venture, John MacDonald. "We understand and acknowledge with this resolution that our performance did not meet our commitment to the public or our own expectations. Above all, we deeply regret the tragic death of Milena Del Valle in the I-90 tunnel.
"Our companies have a long history of delivering safe, high-quality engineering and construction services. Our willingness to scrutinize our own performance and learn from experience has been a major factor in our success.
"Going forward, we will implement a number of specific measures to apply lessons learned to our future work, such as improving quality management systems, more-extensive and mandatory training for field engineers, and additional standardized specifications for design and construction."
The National Transport Safety Board faulted Bechtel and Parsons Brinckerhoff, along with the section designer, in their 2007 expert review, for failing to identify potential long-term creep in the anchor adhesive and to account for possible anchor creep in the design, specifications, and approval process for the epoxy anchors used in that portion of the tunnel.
It also faulted Bechtel and Parsons Brinckerhoff, along with the construction contractor, for failing to continue to monitor anchor performance in light of earlier anchor displacement.
The NTSB faulted Powers Fasteners, the company that packaged, marketed, and distributed the epoxy, for failing to provide the Central Artery/Tunnel project with sufficiently complete, accurate, and detailed information about the suitability of the company's Power-Fast Fast Set epoxy for sustaining long-term tensile loads and for failing to determine that the anchor displacement was due to the use of this epoxy, which was known by the company to have poor long-term load characteristics.
They have since been indicted by the Commonwealth of Massachusetts for involuntary manslaughter.
The Massachusetts Turnpike Authority, Gannett Fleming, the section design consultant and Modern Continental, the construction contractor were also singled out.