One way of thinking about the validity of your actions as an engineer is to imagine how they would be perceived by the inquiry following a disaster involving your work. A while ago I used to be a bit apologetic, almost embarrassed, if I suggested this as a reason for making a decision. It seems to be such a self-interested approach, covering your rear in case it gets kicked very hard by some high-profile enquiry with extensive media coverage. Surely engineering decisions should be based on sound engineering, not on imagined future public perceptions?
Over time I’ve become more relaxed about this way of thinking, to the extent that I now believe it is not only entirely valid but (in some circumstances) exactly the right way to think.
I’m talking here mainly about engineering decisions that involve an element of judgement such as is ubiquitous in safety management studies. On the other hand if you are doing a stress calculation to determine the dimensions required to resist a load then thinking about public perception doesn’t apply – there is not much scope for judgement.
When judgement is necessary, if something later goes wrong then that judgement itself will be subject to scrutiny and judged. That’s when it is right to think like the judge heading the inquiry or Royal Commission into the disaster.
Risk assessments (including pipeline safety management studies) are semi-technical exercises where engineers make judgements about the level of risk that the community considers tolerable. Emphasis on community. And after the disaster, who is the official representative of the community? The presiding judge. So thinking like the judge is the right approach not because of the backside-covering logic but because the judge (or chief commissioner or whoever) is the manifestation of the community that engineering is trying to serve.
Of course, there is no guarantee that every disaster inquiry will reach conclusions that the technical members of the community think are reasonable. Two stand-out examples of legal outcomes that seem, umm, unusual were firstly the recommendation of the Queensland Floods Commission of Inquiry (March 2012) that three flood engineers should be investigated by the Crime and Misconduct Commission not for what they did but the way they said they interpreted their (ambiguous) manual, and secondly the very recent 6-year sentences for seven Italian seismologists (October 2012) as a result of their alleged failure to predict an earthquake that caused 309 deaths.
But most inquiries produce thoughtful and sensible results. (And even for the Queensland flood inquiry I’m picking on only one item in an 18 page list of thoughtful and sensible recommendations.)
I think it is entirely reasonable to think like the judge.