To engineer is to design, `making something that has not existed before'. Petroski provides insights into the design process (which involves computers extensively nowadays) and its limitations, and also the means employed by engineers to prevent failures in their designs.

He emphasizes, however, that it is not possible to anticipate all possible ways a design can fail and thus failures inevitably occur because engineers are, after all, humans. Numerous examples of catastrophic structural failures throughout history are presented and discussed. All involved the tragic loss of lives (for instance, the collapse of two crowded suspended walkways onto the crowded floor of the Kansas City Hyatt Regency hotel in 1981) except the collapse of the Tacoma Narrows bridge in Washington State in 1940.

Petroksi also discusses the failure analysis or forensic engineering that is performed in the wake of a catastrophic design failure to understand how and why the failure occurred. He argues convincingly throughout the book that understanding such design failures can advance engineering more than successes. Design failures, like other failures in life, should be embraced, rather than denied or ignored, and learned from. Great engineers, and great people in general, are the ones who heed George Santayana's famous dictum: `Those who cannot remember the past are condemned to repeat it.'

31 of 33 found the following review helpful:


Why can't a car be built that is totally crash-proof?  Feb 14, 2001 By Joanna Daneman
The answer is well explained in this book. By the time you built such a car, it might be so heavy it couldn't move!

The real interest in this book are the analyses of various disasters that should have been planned for, but weren't.

The most terrible engineering disaster (and the reason I bought this book) was the collapse of the sky walkway in a hotel in Kansas City in the 1980's. I was just returning from KC when I heard the horrific news on the radio. The skyway collapsed during a dance, killing hundreds and injuring more in a dreadful disaster. I was very upset by this terrible event. Why did this happen?

The explanation in "To Engineer Is Human" is really brilliant; the walkway was designed "properly" with a bolt that went through the beam supporting it. But it could not be built as designed because the bolt couldn't be installed in the vertical support. Instead, the builders split the vertical support into two parts in order to install two bolts, and each part was then able to move independently, causing a shear force that eventually led to the disaster. A brilliant analysis and one that showed that despite correct design, the plan must be able to be implemented to work--or else the execution of the plan may doomed to disastrous failure.

That lesson is really important when you are engineering anything, even software. You may specify an important feature, but if the R&D department cannot implement the plan, the product may fail to meet its goals, even be defective.

The book is a bit "thin"--I wanted more and wished it were longer and had more detail, but I will say it makes its point and memorably so. After reading it, your eyes will be opened to how things are designed, how things fail and how engineering affects our lives.

26 of 29 found the following review helpful:


This would make a really excellent chapter in a better book  Mar 31, 2002 By Todd I. Stark "Cellular Wetware plus Books"
A deep insight into complex problem solving; it isn't done in a single brilliant step but in smaller steps while learning from our mistakes.

This isn't a very good book in my opinion, and it's a shame because it's a very strong thesis excellently presented. But all too briefly and too thinly demonstrated. A really great idea that seems to have fizzled for some reason.

The basic idea is that engineering is commonly imagined (at least by people outside of engineering) to be a matter of systematically studying a problem and crafting a great solution. The reality, as the author explains very well, is that engineering efforts viewed in retrospect are more like hypotheses or good guesses at solutions. We craft something that works, and then see the weaknesses and learn from them for the next improvement.

The point is that improvements are not simply a matter of meeting new customer demands or adding new features, nor even just correcting avoidable mistakes. Some corrections and improvements are neccessary because complex systems have aspects that really can't reasonably be predicted at design time. The mistakes don't just arise because engineers are less than perfect, but are an intrinsic part of the process of human beings engineering complex designs in the real world. There is rarely if ever even the potential for creating a flawless perfect design that anticipates all likely contingencies and second and third order causal effects of even simple changes.

Whether a "zero defect" mentality is helpful or not as an ideal, it doesn't reflect how engineering actually works, at least when complex systems are involved. The reality of human engineering is that intermediate failures are an important part of the process. Engineering methodology needs to take this into account, and make best use of it, or else lead engineers in a futile struggle for a perfect initial design and forever wonder why they fail.

Although the I think the idea is very solid, useful, and important, this book certainly lacks the depth it needed to make the point and would have made an excellent chapter in a more detailed book. There are important issues raised here, but not answered, about how to improve the engineering process based on this insight into the role of failures.

As a companion to this, I recommend Dietrich Dorner's cognitive science account of the origin of planning failure in complex systems in "The Logic of Failure." Dorner explains in more detail, with the help of his problem situation simulation research, why consequences are so difficult to forsee and plan for.

18 of 19 found the following review helpful:


What every engineer and designer should know...  Jun 28, 1997
Why do buildings and bridges suddenly collapse, or why do airplanes fall out of the sky ? Even though since the start of the industrial revolution the relative number of disastrous accidents has gone down, it is still a daily event.
Some great examples are given (most prominently the walkway of a Houston hotel that collapsed during the opening ceremony) with pictures and detailed analysis. Great stuff even for non civil-engineers since with some imagination you may learn some more general design lessons.
The editorial side of the book is less impressing, most facts and interpretations are repeated 3 or 4 times throughout the book (excluding the introduction and back flap) so I never got further than 3 quarters into it, preventing myself from another deja vu.
In any way, a veryimportant and useful read.

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