Check out the Boston Globe’s coverage of the engineering failure of its Big Dig Tunnel Project. (You may need to register for free.) This is a perfect case study of engineering failure – it reads like a chapter out of one of Henry Petroski’s books. The December 24, 2006 article entitled “Cheaper, Faster Path Led to Failure” by Scott Allen and Sean P. Murphy is particularly horrifying, in that it shows how the need to keep construction costs under control can trump safety concerns and engineering design factors. One young woman died in the July 10, 2006 ceiling collapse. Factors that influenced the resulting collapse of the tunnel ceiling include:
- Obsessive need to control costs exhibited by the engineering firm and the Massachusetts Turnpike Authority
- This need to control costs led to the following gaffs:
- Low margin of error for safety in the resulting concrete ceilings,
- Use of heavier, but cheaper concrete ceilings,
- Use of bolts installed with epoxy rather than nuts,
- Calls to reduce the number of bolts holding the ceiling up,
- Mistakes made by laborers in installing the epoxy bolts,
- Engineers and project managers ignoring the problems that cropped up, such as bolts coming loose,
- and finally, Big Dig project managers refusing to order additional safety tests, after initial tests showed 10% of the epoxy bolts failed.
If I were an engineering design or civil engineering instructor, I would require the class to study and discuss this tragedy.