Monthly Archives: September 2019

Am I a civil engineering expert?

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I was asked recently, “Are you a civil engineering expert?”

I thought, civil engineering is such a broad field of study how can anyone be an expert?  But then I realized I have knowledge in the field enabling me to form an opinion that will assist the fact finder.  I have degrees and experience in civil engineering and the fact finder doesn’t.  My knowledge is greater in some areas of civil engineering and less in others, but still greater than the fact finder’s.

I was also quick to realize that I had considerable knowledge relevant to the issue being discussed at the time prompting the question of me.  Gaining that knowledge over the years provided insight into some of the sub-disciplines of civil engineering that many civil engineers might not get.

(Civil engineering is a discipline that applies physical and scientific principles to the design, construction, and maintenance of the built and natural environments.  Everything you see around you in the course of a day.  Its history goes back 1,000s of years)

Civil engineering sub-disciplines

You might still wonder if I’m a civil engineering expert when you see a list of some of the sub-disciplines of civil engineering:

  • Structural engineering
  • Foundation engineering
  • Geotechnical engineering
  • Environmental engineering
  • Coastal engineering
  • Water resources engineering
  • Forensic engineering
  • Geomatics engineering
  • Construction engineering
  • Earthquake engineering
  • Industrial engineering
  • Hydraulic engineering
  • Municipal or urban engineering
  • Transportation engineering

So many, and there’s still others.  But, look how a civil engineer can learn about different sub-disciples and be quite useful to a trier of fact:

How we learn about the sub-disciplines

I studied land surveying for two years before studying civil engineering and was licensed as a provincial land surveyor on P.E.I..  My summer work and for a year after I graduated from engineering was construction surveying for municipal water supply and sewage collection pipeline construction.  I also assisted construction surveying for 1.5 years during construction of an oil refinery.

So, some good insight gained into refinery construction, municipal work and geomatics engineering, formerly known as survey engineering.

I did highway engineering design work for a year in Vancouver.  I also got introduced to geotechnical engineering in Vancouver that included field testing of the sub-grade soils along 200 miles of highway in the Yukon.  I did foundation design and structural engineering while in Adelaide, Australia, and geotechnical engineering investigation of embankment failures in Brisbane and northern Australia.

All relatively short periods of time but real good introductions to the sub-disciplines.

I’ve not done hydraulic engineering or industrial engineering but that’s okay; you can’t do them all even if you do a lot.  (I did investigate the ground conditions for construction of hydraulic structures like dams and canals)

I eventually specialized in geotechnical engineering and did graduate work in the U.K. where I practiced for three years then continued in Canada.

Geotechnical engineers investigate and identify the different layers of soil beneath a planned construction site and test and measure the physical properties of these materials.  The soil properties are then used by engineers to design foundations that will safely support the structure planned for the site.

Geo engineers also design and monitor construction of earthwork structures like embankments, filled ground and highway cut slopes.

They must talk with owners, architects, site engineers, environmental engineers, structural engineers, foundation engineers, construction engineers – all sub-disciplines of one kind or another – to learn about the structure that must be supported on the ground.

Structures like low- and high-rise buildings, roads, bridges, dams, canals, retaining walls, towers, wharves, harbours and breakwaters, earthwork embankments and highway slopes.

Civil engineers get informed

You can just imagine as the years go by, how a civil engineer becomes quite well informed about these engineering sub-disciplines, and the different structures forming the built environment we live in.

(Hope your eyes are not glazing over yet – it really is like this in civil engineering)

Geo engineers overlap with environmental engineers

If you work in geotechnical engineering it’s not too long before you’re overlapping with environmental engineering.  Environmental engineers have a big interest in everything to do with water in the environment.

Surface water and ground water (the water table) changes the physical properties of soil and rock.  Sink holes like those in Oxford, Nova Scotia are a prime example.  Gypsum bedrock will support foundations quite nicely when dry but dissolves when exposed to ground water.

If you work in geotechnical engineering it’s also not too long before you’re doing Phase I, II and III ESAs – Environmental Site Assessments.  As a civil engineer, I’ve done a few of these over the years.  There’s a lot of overlap between the geotechnical and environmental sub-disciplines.

Sub-disciplines connect with their co-sub-disciplines

It’s the same with the other sub-disciplines and how they connect with their co-sub-disciplines:

  • Foundation engineers learn something about geo work, structural engineering and environmental engineering:
  • Highway engineers learn about geomatic engineering, and quite a lot about geotechnical engineering because highways sit on the ground;
  • Municipal engineers learn about geo engineering too because pipelines are buried in the ground;
  • Many sub-disciplines learn a little something about environmental engineering because engineering the built environment alters the natural environment
  • Structural engineers soon learn about earthquake engineering
  • Coastal engineers learn about the requirements of foundation engineers and environmental engineers

It goes on and on, the inter-relationship of the civil engineering sub-disciplines.

The principal engineer

However, it’s important for a civil engineer to know when to assume the position of principal engineer. (Ref. 1)

Principal engineers coordinate the work of other engineers and specialists to a common goal – in forensic engineering, to determining the cause of a collapse or accident in the built environment.  A principal engineer might be directing the efforts of construction engineers, structural engineers, mechanical engineers and crane operators in removing the collapsed crane from the multistory building in Halifax. (Ref. 2)

I’m not qualified to do structural and construction engineering but can develop some of the parameters enabling them to do their work, particularly soil and rock properties for foundation design.  I am qualified in earthworks design and also done a lot of materials testing and site inspection (earthworks and concrete construction).

I’m certainly qualified in knowing when to step back into the position of principal engineer, and well out of the way of those who know better.  I know when to retain one or more of the sub-disciplines because I’ve worked with them.

For example

I investigated a nail gun accident a few years ago.  It was easy for me to check if the nail gun appeared to work properly because I used one when I built my house from the ground up.

But, were hidden parts of the nail gun worn?  I’m not a mechanical engineer so I retained a specialist in nail gun repair to take it apart and tell me.

Was it poorly designed or manufactured?  I was ready to retain specialists in these fields.

First however, I decided to have the victim re-enact the nail gun accident while I took a video.  I take a lot of pictures and video in my expert work and this was easy for me to do as principal engineer.  The video of the re-enactment was insightful to say the least.

In other cases, I retained a structural engineer to guide me in underpinning a structure.  I retained a specialist in concrete design to guide me in retaining wall design.  I’ve got a call to a structural engineer now about bracing a deck structure so it won’t fall over.

Family doctors as principal investigators

The concept of principal investigator is not unique to civil engineering.  The medical profession adopts this approach all the time.

Your family physician takes a patient history, does a physical examination, may order some tests and may refer you to a specialist if s/he sees a potential problem.  He would coordinate the investigations of the other doctors and specialists into the problem.  The specialists would carry out thorough investigations and explain their findings in detail.  (Ref. 3)

It’s similar in construction when a general contractors hires carpenters, electricians, plumbers and roofers to do a job.  The general is the principal, the trades are the specialists.

***

So, what did I say?

Thinking through all of the above got me comfortably to the stage of answering the question put to me, “Are you a civil engineering expert?”.  What do you think I said?

References

  1. Lewis, Gary L., Editor, Guidelines for Forensic Engineering Practice, American Society of Civil Engineers (ASCE) Reston, Virginia 2003
  2. Why do I think the crane collapsed in Halifax?, posted September 20, 2019
  3. Personal communique with Dr. J. Nasser, Halifax, NS. September, 2019

Why do I think the crane collapsed in Halifax?

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I’m not surprised the crane collapsed in Halifax during Hurricane Dorian, and an initial hypothesis of cause is easy.

The crane was set up for construction of a multistory building next to The Trillium, 1445 South Park Street.  A friend of mine happens to live in The Trillium.

In collapsing on September 7, the crane just lay down against the street side of the approximately 12 story, unfinished building.  It then went over the top and down the side facing The Trillium, the top of the crane scraping the side of The Trillium on it’s way down.

It looks like a kinked, yellow ribbon thrown over the multistory building.  I counted at least six kinks in the ribbon/crane.  It would speak well for the structural design of the multistory building if it hasn’t been damaged structurally on being whipped by the falling crane.  It seemed to resist the horizontal push of the falling crane quite well.

Google crane collapse Halifax for excellent photographs and video of the crane draped over the building.

***

Cranes are good at lifting vertical loads/weights not in resisting horizontal loads, like wind.  And if the horizontal load on the crane is a frequent gust of wind from different directions – Dorian was characterized by frequent wind gusts rather than a steady blow – then you’ve got an oscillating load, an on-again, off-again load on the crane.  Worst still.

These kinds of oscillating loads caused three, 1.5 metre deep, steel bridge girders, that were connected to a crane, to fail by bending sideways in Edmonton in 2015. (Refs 1 to 4)

The steel bridge girders were new yet they bent under an oscillating load.  The word on the street is that the Halifax crane was rusted and perhaps not so new.  Not good.

But you say, the open lattice-type construction of the crane doesn’t provide much surface for the wind to push on.  Still some, and Dorian’s wind gusts were not light weight by any stretch.  Have you seen a thin, hanging rope, steel chain or cable swinging back and forth in the wind?

Given the preliminary evidence, an initial hypothesis as to why the crane collapsed is wind load in excess of the crane’s capacity to resist.  A wind load characterized by frequent, strong gusts from different directions.

The resulting oscillation of the crane would cause metal fatigue – a well known cause of failure in engineering – and the crane to break at the location of the first kink.  The upper kinks in the yellow ribbon/crane would form as a result of hitting the stronger multistory building.

***

I examined the collapsed crane from outside the security fence near the corner of The Trillium.  I also talked with a man who was evacuated from a building near the collapse and another man at The Trillium.

Hands-on examination of the crane and more evidence is certain to result in revision of my initial hypothesis as to cause, but I know I’m close.  Regarding more evidence, it’ll be interesting to learn the condition of the crane – the rust factor you hear on the street.

***

This is what scientists do, an initial hypothesis on an issue, a simple thought, sometimes on the basis of the skimpiest evidence.  They’ve got to start somewhere.  Then, based on more evidence, they tweak, revise and modify their initial thought, and sometimes throw out the initial hypothesis completely.

Applied scientists like forensic engineers and medical doctors do this too – ask your doc next time you see him or her about differential diagnosis.

It’s important for clients of forensic engineers and experts to realize that an initial hypothesis is not the last word on cause.  It’s just a good start.

References

  1. Wind, construction crane and inadequate cross-bracing caused Edmonton bridge failure.  An initial hypothesis.  Posted March  27, 2015
  2. Why, in a recent blog, didn’t I seem to consider foundation failure as a possible cause of the Edmonton bridge collapse?  Posted April 3, 2015
  3. Bridge beams that fail are sometimes like balloons filled with water – squeeze them and they pop out somewhere else.  Posted May 20, 2015
  4. Bridge failure in litigation due to inadequate bracing – City of Edmonton.  But, inadequate for what?  Posted March 15, 2016