Is it important to know that a lot of the built environment has not been engineered but built on experience? Built on the basis of personal and first hand knowledge, observation and practice – that is, experience. Rather than on the application of science and mathematics – engineered. It is as I show in the following.
When was the last time you thought about the depth of a telephone pole in the ground and how this was determined – so it wouldn’t get pulled over by the power lines tugging at the top? And related, how the anchors for the pole’s guy-wires are figured out and constructed?
Not big issues you say? But note how some poles lean next time you’re driving around.
A leaning pole near where I live had a new anchor and guy-wire installed in the last couple of days, alongside the old anchor that didn’t work. Looking up you see lots of wires near the top tugging on one side but none on the other side. Was the new anchor engineered or experienced? Obviously, the old one wasn’t engineered because the pole leaned.
How about the foundations for your house and all the others on the street? For that matter, foundations for all kinds of structures.
We’re absolutely certain the foundations for a multistory building are designed by an engineer but what about a single story commercial building in an industrial park?
How about the foundations for the piers and buttresses of a bridge? I’m sure the foundations for the piers at a river crossing are engineered. But, what about those simple abutments?
When was the last time you wondered who built the drip loops on the power supply to a commercial building – an engineer or an experienced person? Then wondered what happens during heavy rain and strong, gusting winds out of the southeast?
(Drip loops are loops in the power lines from the street to a building. They are located near where the cable enters the building. Rain water on the lines drip off at the loop down rather than run along the cables and into the building. Except they don’t work well in heavy rain and strong winds with up-gusts as I determined recently – they fail in engineering terms)
What about the retaining walls along our streets and highways? And the paved bike paths in our green belts?
Also the soil slopes along our holidays? For example, see the highway slope failure near Exit 10 on Hwy 104 in Nova Scotia. It’s subtle but it’s there. Is that an engineering failure or an experience failure?
What about those large steel or concrete culverts carrying roads and streams beneath our highways. Are they engineered or experienced?
And those tall, slender propane tanks at service stations? For certain, the steel tanks have been engineered but what about the foundations to resist overturning of the tanks in strong winds?
I can give more examples but that’s enough; I’m sure you get the picture.
I thought of this as I was driving about recently – so much of what we see constructed is based on experience. There are no engineers involved.
Why take an interest if things are working most of the time, performing as they should? Regardless of whether they were engineered or built on experience.
How is this relevant to understanding forensic work, the objective of this blog site?
Here’s why it’s relevant and important to take an interest
Things do fail and also occasionally injure people.
For example, if a kid on a bike falls and is injured after hitting a pot hole on a bike path what happens during the forensic investigation? Lots of bike paths are built based on experience. But pot holes form because of well understood engineering principles.
Or an electric room in a commercial building floods in spite of the engineered or experienced drip loops? What happens during the forensic investigation?
Or a highway slope fails, a bridge collapses, or a telephone pole leans?
We can figure out why something failed – the easy part. But determining the standard of care and what a reasonable person would do is tougher when the thing was built based on experience.
Who should determine the standard? A planner, an architect, a design engineer, a construction engineer, another experienced person, the owner of the structure, someone else?
And if things work quite okay, should we, nevertheless, wonder if they’ve been engineered or experienced – particularly things used by the public!?
Things built on experience are sometimes overbuilt and cost more money than they should. And sometimes they’re under-built and cost more money when they fail and occasionally injure people.
It’s important to take an interest because lots of questions arise when something fails that was built on experience, not engineered.
(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada firstname.lastname@example.org)