So, the other thing is, this is the Minnesota River Bridge, in the US. I don’t know if you remember.
In 2007 it collapsed; killed 13 people, 145 injured.
This is the Mississippi River and it made worldwide news at the time. The bridge dropped into the Mississippi River while they were repairing it, by the way.
The thing was, if you go back to the 1970s and 80s, in engineering, there were quite high factors of safety built into things. Maybe two, three, four times factor safety for civil designs, for construction and stuff like that.
As we’d try to take out cost and become more efficient in our system, we’ve taken factors of safety up but we don’t know – because if we go back to that hidden risk, that’s your factors of safety but we don’t know.
We can’t explain as engineers or asset managers, how much we’re taking out and what it is doing to our risk.
And so the net results is the Flint type incidents or this. Once you take, yeah you get a spectacular failure of the system or process civil engineering, or a dam or whatever it is. People die.
And it’s all very spectacular but it’s all about losing factors of safety through changing service levels and changing the cost.
So asset plans help you examine all these sorts of stuff but this is the wrong end of it. If you are the asset management engineer for that bridge, that’s not a good day of your life.
It took them 18 months to build a new one and that was like on a major interstate, so it would have stuffed up the traffic flows in the city for 18 months as well.
[…] Factors of Safety and How to Model and Communicate Risk Trade-offs […]