Sunday, May 16, 2010

Beware small, individual decisions

Several of the NOLA Bloggers are drawing parallels between the ongoing BP oil geyser disaster and the catastrophic failure of floodwalls protecting New Orleans in 2005. I certainly agree that there may be similarities in these two different engineering debacles, but we have to be careful.

There is still a lot we don't know about what happened out in the Gulf of Mexico last month and why all the safeguards, standards, precautions, fail-safe systems, redundancies and the workers who lost their lives were not able to avoid or contain the dangerous conditions of mineral extraction. Until we do know--and that may be years--we need to keep an open mind to all the possibilities.

In contrast to the BP disaster, we now know a great deal about what happened and why before, during and after Hurricane Katrina. At different locations where constructed features did not perform properly we know there were specific reasons that those point failures occurred.

But the most significant and dangerous condition was not the result of a single point of failure or isolated bad engineering decision. The most devastating factor in my opinion was what is known as "The Tyranny of Incremental Decisions."

Simply put, during the long trek from project conception to operation, a long list of changes and compromises were made that individually didn't seem significant but which added up in a project doomed to failure. Some of those decisions may have been the result of budget pressures, or local preferences, or just ill-informed good intentions. Poor Richard advised that small strokes fell great oaks; The Tyranny of Incremental Decisions can be viewed in that manner.

As we learn more about the BP oil geyser disaster, I won't be surprised if the news media, politicians and many private citizens clamor for a single point of failure, a "smoking gun" that can be blamed. There may well be one. But I would not be surprised to learn that a series of decisions made by different people at different times had a large role to play in undermining the overall safety and reliability of the drilling operation.

(If you want to read the whole sordid tale about how The Tyranny of Incremental Decisions left New Orleans vulnerable, check out the Hurricane Protection Decision Chronology, or read the synopsis as reported in The New York Times here: Engineers Faulted on Hurricane System.)

(Editorial edits on 17 MAY 10)