August 2, 2007

Quote from engineer James Arnheim in the book “Forensic Engineering,” edited by one of my professors at WSU, Kenneth Carper:

“Structural Engineering is the art and science of molding Materials we do not fully understand; into Shapes we cannot precisely analyze; to resist Forces we cannot accurately predict; all in such a way that society at large is given no reason to suspect the extent of our ignorance.”

There is much truth in the statement above, which is why engineers use large safety factors in design to try to account for the unknowns. It is also why the NTSB investigation into the tragic collapse of the I-35W bridge yesterday needs time to figure out what lessons can be learned, and how those lessons can be applied. The greatest advances in engineering come from investigating failures. The American Society of Civil Engineers has been trying to get the public to pay attention to our aging infrastructure for years – bridges, water systems, sewer systems, roads. It is so easy to be distracted by building new programs, new “stuff” and not pay attention to the long term budget affects of funding new programs or the physical impact of deferred maintenance or delayed replacement. New programs are described as having a “bow wave” effect; I think I’ll start asking if deferred maintenance will have a “bridge collapse” effect.

The Mayor of Minneapolis today thanked people for the outpouring of condolences and support immediately after the tragedy. He also made a plea for all of us to remember his community throughout the long recovery and grieving process. We are an impatient people. I pray we have the perseverance to pay attention to this tragedy and start thinking for the long term when we set priorities and plan budgets. I’ll bet CNN stops airing live press conferences from MinDOT structural engineers by tomorrow, and coverage will slip back into the technical press. I might just have to renew my subscription to Engineering News-Record to get the real story.