Thursday, 4:30 PM
NTSB documents offer glimpse into Big Dig investigation
(National Transportation Safety Board)
By Andrew Ryan, Globe Staff
Federal investigators released two fundamental findings after a yearlong probe of the fatal ceiling collapse in the Big Dig: contractors used the wrong kind of glue, and project oversight was inadequate to detect the problem.
To support those conclusions, the National Transportation Safety Board also made public a trove of almost 2,000 documents, laboratory reports, interviews, depositions, and photographs that chronicle the investigation. The Globe has uploaded a sample of some of the material on Boston.com.
The data include a laboratory analysis of the glue and its properties; a study of the tendency of bolts to slip or creep out of place; and a brochure from Powers Fasteners describing the quick-drying epoxy and other company literature outlining the torque capabilities of its products.
Included in the documents is correspondence between Modern Continental Construction Co. and Bechtel/Parsons Brinckerhoff, the consultant hired to manage the overall design and construction of the project. One letter dated Oct. 7, 1999, addressed what was described as "signs of movement" with adhesive anchors. Another document from Oct. 15, 1999, describes the procedures for installing the precast module ceiling.