We learn from failures. They contribute to successful design. I also like investigating the cause of failures as a means of resolving disputes, sans judicial process. There’s too much discord in the world now without duking it out in court too.

You can read all about learning from failures in To Engineer is Human, The Role of Failure in Successful Design by Henry Petroski. He cites examples of well known failures like,

• The Tacoma Narrows Bridge in 1940 – a video online of the failure is something else to watch. Lesson: The effect of wind on a suspension bridge like those over Halifax Harbour.
• The Nyatt Regency Hotel walkway collapse in 1981. Lesson: Tiny, inadequate structural connections can cause big problems and the deaths of 114 people.
• Roof collapses: The Hartford Civic Centre roof collapse in 1978 and the Kemper Arena roof collapse in 1979 Lessons: I haven’t researched the causes but easy to imagine – an initial hypothesis – inadequate structural design and/or construction of the roof support system.
• We all know about the Ocean Ranger going down off Newfoundland in 1982. Lesson: Provide backup in the event sea water breaks a window, as happened in this case, and gets into the ballast control room. And this cause the control panel to malfunction and the drilling platform to roll over in the rough seas running at the time.
• The space shuttle Columbia exploding on re-entry in 2003. Lesson: Be wary of cultural traits and organizational practices detrimental to safety being allowed to develop as happened in this case.

Petroski explains what was learned from these failures and others and how engineers think when they’re designing a structure.

Enough has been learned from failures that engineers often know the probable cause of a failure before they get on site. I’ve told you this before.

Petroski’s book is a good read – almost exciting – in fairly simple, jargon-free language. There’s the odd big word and abstract concept but not many. He also mentions a couple of other good books on failures which I mention below. One of these books is considered required reading for engineers, architects, civil litigation lawyers, and insurance claims managers.

Read his book, and like me, you’ll go about your daily chores looking and seeing the failures in our built environment. For example:

• A paved driveway with cracks a couple years after the asphalt truck left. Lesson: The subgrade of a simple driveway needs to be well drained to prevent frost heave. Sometimes to a depth of two or three feet rather than inches, if you don’t want any cracks at all.
• The varying height of a curb along a short stretch of residential road. Lesson: The road bed needs to be well constructed and compacted right out to the curb.
• A leaning basketball practice hoop in a kid’s playground a few days after construction. Lesson: Even a kid’s hoop needs to be founded deep enough in the ground and the back fill soils well compacted.
• The thump-thump at a depression in the highway. Lesson: The subgrade and highway embankment need to be well designed, constructed and compacted everywhere, particularly where pipes are laid beneath the highway in a trench after the highway is constructed.
• The sloping door threshold in an elder’s washroom. Lesson: The floors in an elder’s facility need to be designed and constructed at the same level – a simple design and construct problem.
• The irregular, sloping floor surface in a high rise. (I know something about high rise construction. When I saw this – an easy call – I thought sloppy, too fast construction. I knew the job supervisor and the pressure he was under to get the high rise up) Lesson: Take the time to support the floors properly during construction, ensuring the concrete forms are level and well supported before placing concrete.
• A highway slope failure – a mini landslide – where soil has been excavated to form the highway. For example, the slope on the west side of Highway 102 at Exit 10. Lesson: Excavate the slope at the angle of repose of the soil.
• A lake contaminated with sediment from a construction site. Lesson: Design and construct adequate erosion and sedimentation control structures using simple, well understood methods in handbooks.

(I can’t help but think I could prepare a similar list to the above for slip, trip and fall accidents, for certain the ones that I’ve investigated. Another time)

An experienced engineer knows the probable cause of these failures from the get-go.

Some of you will say some of these failures are due to poor construction. I will say you’re right, in a sense. But, I will point out that the poor construction is due to poor construction inspection – quality control – looking and seeing during construction that you’re getting what you’re paying for – which is a design task.

***

Based on what the engineer in me knows, there are some places I won’t go and things I won’t do because of suspect design and/or construction.

And, increasingly, I’m less inclined to fly. If the airlines can mess up the scheduling like they did last Christmas could they mess up plane maintenance and repair? Look what happened to the space shuttle Columbia mentioned above.

Plane maintenance is sometimes contracted out – and sometimes to the lowest bidder, who must focus on the bottom line as well as fixing the plane.

I thought this on a chat with a friend who is an aviation mechanic, months ago and well before the Christmas scheduling mess.

It’s not just me. I exchanged emails with a friend a few days ago who investigates traffic accidents. He was on his way to Orlando, Florida to take a course in accident reconstruction, and wasn’t looking forward to flying. I wonder why?

***

The lists in this blog have come from an engineer’s love of failure and learning from them. That engineers make mistakes is forgivable; that they catch them is imperative.

I had that concept drilled into me years ago – pre-engineering – by Major James A. H. Church, our instructor when I did a two year diploma course in land surveying at the College of Geographic Sciences in Nova Scotia: It’s okay to make a mistake as long as you catch it! The Major was fierce about this.

References

1. You could be excused for thinking that everything is falling down. Blog posted July 23, 2020 Updated October 13, 2020
2. What’s in the built environment and how many ways can it fail? Blog posted July 8, 2020
3. How many ways can a building fail and possibly result in civil litigation or an insurance claim. Blog posted July 10, 2014
4. Nicastro, David H., ed., Failure Mechanisms in Building Construction, ASCE Press, ASCE, Reston, Virginia 1997 This is a real good, well researched read by the American Society of Civil Engineers.
5. Petroski, Henry, To Engineer is Human, The Role of Failure in Successful Design, Vintage Books, Random House, Inc., 1984 Petroski covers a lot of ground in 17 chapters, 251 pages and pithy comment. As he says in the Preface, the book is his answer to the questions “What is engineering?” and “What do engineers do?”. You’ll read some of the answer in Chapter 14, page 172, Forensic Engineering and Engineering Fiction. And the rest of the answer in the remainder of the book.

Appendix: Causes of Failure

Petroski also notes causes of failure as cited in Thomas McKaig’s 1962 book Building Failures. This is a widely known collection of case studies intended for the use of engineers, architects, contractors, and claims managers. The following list in McKaig’s book comes from another, long ago source lost in the mists of time, but still rings with relevance:

1. Ignorance a. Incompetent men in charge of design, construction, or inspection. b. Supervision and maintenance by men without necessary intelligence. c. Assumption of vital responsibility by men without necessary intelligence. d. Competition without supervision. e. Lack of precedent. f. Lack of sufficient preliminary information.
2. Economy a. In first cost. b. In maintenance.
3. Lapses, or carelessness a. An engineer or architect, otherwise careful and competent, shows negligence in some certain part of the work. b. A contractor or superintendent takes a chance, knowing he is taking it. c. Lack of proper coordination in production of plans.
4. Unusual occurrences a. Earthquakes, b. Extreme storms, c. Fires, d. And the like.

Petroski’s book also notes some causes of structural failure as listed in D. I. Blockley’s book, The Nature of Structural Design and Safety, another good read:

1. Limit states a. Overload: Geophysical, dead, wind, earthquake, etc.; manmade, imposed, etc. b. Under strength: Structure, materials instability c. Movement: Foundation settlement, creep, shrinkage, etc. d. Deterioration: Cracking, fatigue, corrosion, erosion, etc.
2. Random hazards a. Fire b. Floods c. Explosions: Accidental, sabotage d. Earthquake e. Vehicle impact
3. Human-based errors a. Design error: Mistake, misunderstanding of structural behaviour b. Construction error: Mistake, bad practice, poor communications

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada, April 20, 2023. ejorden@eastlink.ca)