About admin

I am a consulting professional engineer with 38 years civil and forensic engineering investigative experience. I have worked on civil engineering projects, and forensic and insurance cases, in eastern, western and northern Canada, offshore Nova Shore, the Beaufort Sea, and overseas in the Caribbean, the U.K. and Australia. Civil engineering alters and reshapes the natural environment to provide built environment to meet the needs of mankind. Civil engineering includes the planning, design, construction and maintenance of structures making up the built environment. Examples of these structures are industrial, commercial and residential low- and high-rise buildings, also bridges, roads, dams, drainage systems, earthworks, and hydraulic works. Included is the plant and equipment in the buildings and the infra-structure servicing the buildings. Forensic Engineering investigates the cause of problems and failures with these structures as well as the cause of traffic and industrial accidents that occur in the built environment. The technical data from an investigation is used by the judicial system in determining damages. I practiced as a provincial land surveyor on Prince Edward Island, Canada before studying and practicing civil and forensic engineering.

Animation in Forensic Work: Use and Misuse

I learned recently that computer animation, and modelling or simulation, while useful in forensic work, including accident reconstruction, can also be misused. Sometimes by mistake, other times deliberately.

It doesn’t help that software sellers claim accuracy but don’t give data backing up their claim. Nor do the claims that animation can help “build a solid case” when forensic experts must be objective in serving the judicial and dispute resolution processes.

I wonder to what extent each of you are aware of these problems:

  • Insurance claims adjusters
  • Civil litigation lawyers
  • Dispute resolvers
  • Injured parties, in general

If you’ve got a few moments, the following is certain to enlighten you.

***

To animate means, figuratively, to “give life to”. For example, make an object seem to move. The moving cartoon figure seen in a TV commercial or a teenager’s cell phone might begin as two inanimate pictures of a figure with the head or an arm in different positions in each picture. Animation software adds additional pictures between the two with the head or arm in slightly different positions. This gives the appearance of movement to the cartoon figure’s.

A distinction must be made between animation which simply moves objects between specified start and end positions and modelling or simulation which does this based on characteristics of the object.

For example, in modelling the characteristics of a vehicle like a car might be it’s weight, tire friction, and how it brakes and steers. In animation these characteristics might not matter so much.

***

The object in forensic work might be a car involved in an accident that an expert is reconstructing to determine cause.

The expert collects data from the accident scene like the road conditions at the time, the location and length of skid marks, car specifications and impact speeds.

Animation and modelling software allows the reconstruction expert to place this data on a Google earth image or on a photograph taken from a drone or an airplane. The expert can also add data like labels, text and direction of travel.

If the topography of the site and the location of things on or beyond the road have changed since the aerial photographs were taken, the software allows the expert to correct this data.

In the old days this would be done by a draftsman drawing the scene from a land surveyor’s notes and adding the data from the reconstruction expert. Slower for sure but also more accurate.

After getting this input the animation/modelling software provides a set of data which describes the motion of objects at the accident scene – not unlike the cartoon figure in the TV commercial. For example, the speed and direction of travel of the cars involved in the accident.

***

The reconstruction expert can correct the software input data based on evidence from the scene if the output from the software is at odds with the field data. For example, the location of skid marks or the location of damage on the car.

This would be good use of animation software – as long as the accuracy of the software is understood compared to actual measurements at the scene by an expert and/or land surveyor.

Examples of good use

Following are some examples of the good use of animation and modelling software, and supporting techniques like Google Earth and aerial photography:

  1. As indicated above, correcting the input data to the software based on evidence from the scene – taking into account the accuracy of the software
  2. Input honest data to the animation and modelling software, rather than tweaked data designed to produce a desired but misleading result
  3. Checking the accuracy of animation and modelling software used in accident reconstruction At the very least, query the seller about the basis of their accuracy claims. Better still, check using independent data from an accident site or a failure in the built environment. This should be done before or during use of the software Do this for sure during peer review of another expert’s report on forensic work that relied on computer software Example: I read a report one time on an accident reconstruction. The speed of the vehicle was an issue. The software gave a speed that was greater than a verbal report by one of the parties. An independent check using different data confirmed the software output and the incorrect verbal report
  4. But experts and their clients must be careful. Accident reconstruction using a Google Earth picture of a site in an urban area can be very reliable because the resolution of urban Google Earth pictures is good. That of sites in rural areas is poor. This is because Google Earth pictures in urban areas are taken at lower altitudes. Example: I analysed the cause of a retaining wall failure on a residential street in Ottawa using an image from Google Earth. The resolution was so good you could take off the size of cracks in the wall. This kind of accuracy would approach that needed in accident reconstruction using animation and modelling software.
  5. The source of the site image used by animation software is of interest too. Site maps and images based on laser scanners (check Lidar on Wikipedia) are excellent. Unfortunately, they are less available. Example: I investigated the cause of a swimming pool failure in Cape Breton a few years ago – excessive foundation settlement. But why? The site was in a rural area that I was surprised to find had been scanned by a laser. I learned that it was a trial use of this mapping technique – lucky for me and my client. I studied the laser picture – a task called terrain analysis in civil engineering – and saw that part of the swimming pool was built over wetland, a swamp. This was not evident on the ground. Example: On another occasion I investigated the cause of fuel oil contamination of a rural site up on the Cape. In preparation for terrain analysis, I saw that Google Earth imagery was too blurred, the contours on topographic maps were too large, and laser scanned imagery was planned for this very area but not done yet. So I had video taken from a drone of the contaminated site and that solved an important issue at the contaminated site.

You must be careful about the aerial pictures used in animation and modelling software same as you must be careful about the claimed accuracy of the software. Honest input to the software, understanding image resolution, and investigating software accuracy are good uses of animation software.

***

Surprise! A hired-gun-expert could input data from the accident scene but tweaked a little to support building a solid case. This would be naughty use of animation software.

Examples of naughty use

Following are some examples of misuse of animation and modelling software by mistake or design:

  1. Accuracy of a vehicle’s motion.  We know that any velocity, distance, orientation and time can be input to software and then set to motion and recorded as video.   Example: In animation, incorrect, even impossible values can work.  Examination by an opposing expert should be able to find these errors.
  2. Use of animation offered by current software that has realistic, unverifiable effects such as lighting, surface textures, vehicle damage, human figures and colours. The problem arises when the effects are inaccurate, producing video and stills/screen grabs that can prejudice a viewer, without the viewer even being aware of it.  Examples of tricks you can play with software that’s on the market now: (a) Colour and lighting can increase or decrease contrast, causing a human figure representing a pedestrian to appear more, or less visible, or conspicuous.  (b) The sky effect can make a nighttime scene look darker or lighter.  (c) Vehicle headlamps, tail lamps and brake lights can be more or less conspicuous than they actually were.  (d) The light pattern from animated headlamps may well be more or less than produced by the actual headlamps.  (e) The colour and texture of road surfaces can leave a viewer with the subconscious idea that the surface was slippery.   (f) Vegetation (bushes, trees, etc.) can be more or less of a view obstruction/restriction than the actual vegetation.
  3. Animations need to be carefully authenticated for accuracy (both motion and visually) before they are admitted into evidence.  The probative value of evidence needs to outweigh the prejudicial.  Example: The problem can arise when the court is not aware of how, or how much an animation is prejudicial.  That’s when the expert needs to inform their client. 

***

Animation and modelling/simulation software are wonderful tools for those of us doing forensic work.  But using effects that cannot be authenticated must be kept to a minimum.  Some skillful animators can’t seem to resist, whether it’s to produce a pleasing result, or a misleading one, maybe both, intentionally or unintentionally.

***

(In the spirit of Wikipedia, these two sections of my blog can always use additional examples of good use and naughty use of animation and modelling software)

Summary

I’m sure this issue of animation in forensic work is new to a good many non-technical clients representing injured parties. What’s an injured party or a claimant to do surrounded by such technology?

Here’s what you do. Ask questions of the forensic experts about

  • the use and misuse of the animation and modelling/simulation software,
  • the accuracy of the software,
  • the shortcomings of the software, and
  • be on guard and ever alert to the deliberate misuse.
  • And get answers in jargon-free language.

It’s not hard to understand that you can play games with animation in forensic work not unlike what’s done in TV commercials and on kid’s cell phones.

Acknowledgement

The content of this blog is based on my forensic engineering experience, research online, discussion with others in forensic work, and common sense.

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada, January 20, 2022. ejorden@eastlink.ca)   

The humble pig rises to new heights in a heart transplant, and a forensic investigation

I was amazed to learn about the pig-heart-transplant last evening on the TV news! A break-through for medicine and a last chance for 57 year old David Bennett of Maryland. “I may die”, he said, “but they may learn something to help others”. Such a noble thought on the eve of such an operation. He’s doing well three days later.

The news story reminded me about a forensic engineering investigation several years ago when I used skin from the stomach of a pig to test the skid resistance of a sauna floor in a slip and fall accident.

Not in the same league as the medical first but I’m certain an engineering first on the East Coast of Canada if not farther afield. And both typical examples of how Maritimers and Marylanders work things out living close to a fickle sea that throws one surprise after another at us.

There was at least one other first during this investigation, but first, how did I come to test the floor this way?

How did I test the floor with a pig’s help?

We test the skid resistance of a floor using the shoe worn by the victim at the time of the accident, as the drag sled. But, how do you drag a victim’s foot across a sauna floor?

(A drag sled is an object of known weight pulled across a floor and the pull measured. The ratio of the one to the other gives the skid resistance in engineering – the coefficient of friction in high school)

I did think about how I might use the victim’s foot but concluded there was too much risk for the victim and uncertainty in the results.

I remembered that a friend, a professor in the Dal University nursing department used dummies, including dummy legs, to teach nursing students. I chatted with her and examined one of the dummy legs.

It was a step forward but better still I chatted briefly with another in the medical department and learned that doctors recognized pig skin as similar to human skin. They got their pig skin from a butcher in Bedford to teach Dal medical students. A big step forward.

But to be real sure, I chatted with one of my daughters, a veterinarian, and she referred me to a research vet at the University of Prince Edward Island. I called this chap and confirmed that indeed pig skin was similar to human skin.

I went out to the Bedford butcher and got my 15″ x 8″ x 2″ slab of pig skin. Then back to the office to work out using this pig skin as a drag sled. Then to the accident site to carry out standard drag sled tests of skid resistance of the wet, dry sauna floor.

Hmmmm, how does a dry sauna floor get wet?

The penny dropped during an earlier visit and walk-through of the accident site – a shuttered recreational centre with a swimming pool, locker room and showers. These walk-throughs are invaluable when we saunter about the accident site, kick the tires, so to speak, and get calibrated to the site. They are invaluable.

So, on the skid testing day I took my bathing suit and a towel, took a shower – forgetting that the water in a closed rec centre would be cold 🙁 – and walked to the dry sauna dripping water everywhere, including on the dry sauna floor. Then I did my drag sled testing of skid resistance of the wet sauna floor using pig skin that is like human skin.

***

There was nothing in the engineering text books about solving this slip and fall accident, same as there was nothing in the medical books to guide using a pig’s heart to save a guy.

Give us time and leave us alone and we’ll figure things out Down East – experienced forensic engineering experts and medical doctors – and if it’s newsworthy, maybe show up on TV late at night.

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada, January 11, 2022. ejorden@eastlink.ca)   

The ethics of contingency shopping

I was troubled on two fronts recently. One when a firm from away asked if I would investigate the cause of an accident on contingency. The second when I thought to give others a heads up that a firm was looking.

The second came to mind when I declined the commission and I didn’t hear back from the firm. It occurred to me the firm would call the few others on the East Coast who could do this forensic work. I knew the others – should I let them know? I didn’t and that bothered me for a while.

I resolved the two-front, ethical dilemma implicit in this situation after reflecting for a while.

Number #1

My problem with being asked in the first place was that it was at odds with common law requiring that a forensic expert: (Refs 1, 2)

  1. Be independent from the parties that retain them
  2. Provide objective, unbiased opinion evidence in relation only to matters within their expertise, and,
  3. Avoid assuming the role of advocate for the parties that retain them

These requirements are the same in all issues involving dispute resolution and claim settlement. They mean than an expert must engage on a fee basis not on contingency, and accounts kept up to date. Otherwise, s/he would be seen as biased and have a vested interest in the outcome of the dispute. Perception is everything.

The great majority of experts know that they serve the process, as found in a pilot study of 152 Canadian experts, not the party who retains them. (Ref. 3)

But, to be sure that there wasn’t another school of thought out there on experts and contingency I contacted the head of another law firm from away. I haven’t been answered as quickly before as in this case – slammed would be more correct: “Absolutely not!”.

But why would a large, experienced law firm ask an expert if they would take an assignment on contingency? They would know the common law, and also that an expert perceived to be biased would be of no value to the judicial process.

Of course, for the law firm, as advocates for injured parties who do not have enough money to seek justice, it’s seen as an acceptable process for both the firm and the injured party.

I figured the problem developed for the firm because the person who contacted me was a junior lawyer or a paralegal who just didn’t know. Their law firm took cases on contingency, why not an expert?

The junior person gave himself away relative to his experience when he asked me to take the case on contingency. Then saying the case was expected to settle in about a year – it would be a first compared to a more normal several years.

Realizing this, I was satisfied that I was contacted by an ethical firm but represented on this occasion by an inexperienced person.

Number #2

I did not contact the other experts to give them a heads up about a shopper in town. Was I unethical in some way?

I was uneasy for a while. Then I realized that experienced engineers on the East Coast know that as experts they serve the judicial process. (Ref 3) There was no need to alert them. We know there are one or two down here who would be receptive to being retained on contingency but alerting them to the shopper would not change their inclination.

I felt okay after thinking things through on this front too.

Summary

I’m thinking that contingency – getting paid when the money comes in – is okay for some parties to a dispute. It’s the perception, if nothing else, even though it’s more, that’s bad for experts. Add to that the risk of unintentional bias. At the end of the day, all things considered, some parties to a dispute or claim resolution give contingency a wide berth – ethical experts for example.

References

  1. Stockwood, Q.C., David, Civil Litigation, A Practical Handbook, 5th ed, 2004 Thompson Carswell
  2. Principles governing the cost control of dispute resolution and claim settlement involving experts. Posted September 24, 2020. Updated September 24, 2020, March 18, 2021 and December 30, 2021
  3. Corbin, Ruth M., Chair, Corbin Partners Inc. and Adjunct Professor, Osgoode Hall School, Toronto, Breaking the Expert Evidence Logjam: Experts Weigh In, presented at Expert Witness Forum East, Toronto, February, 2018

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada December 30, 2021. ejorden@eastlink.ca)   

What is geotechnical engineering?

Soil like in earth, ground and geo is a building material like steel, concrete and wood. The difference is that the physical properties of soil are unknown at the start of design and construction, unlike most other building materials. This is because soils change with almost every step we take across some building sites.

It’s not a very glamourous material either, but everything in the built environment is supported on soil, occasionally bedrock – so, ignore the soil at your peril.

All structures in the built environment consist of:

  • the upper part that you see,
  • that is supported by a foundation that you don’t see,
  • that is in turn supported by soil that is even deeper out of sight.

Studies in England found that most foundation failures occur because the physical properties of the soil are not determined properly.

A geotechnical engineers’s job is to identify the different layers of soil beneath a site. As part of the process they test the physical properties of the different soils in the field – insitu testing – and in the laboratory. They use these properties to design the soil component of a structure.

Geotechnical engineering, or soils engineering as it was known in the beginning, is one of several civil engineering specialties. (Figs 1, 2)

For example, Structural engineers design the steel, concrete and timber to support the upper part of the structure that you see. Foundation engineers design the footings and piles that you don’t see to support the structure above that you do see. Geotechnical engineers find a layer of soil at the construction site that is strong enough to support the foundations that support the structure. Construction engineers build it. If anything goes wrong, like a failure or a slip and fall accident, Forensic engineers determine the cause.

Geotechnical engineering has been practiced for 1,000s of years – all the way back to the Great Pyramid of Giza, 4,600 years ago – but wasn’t known as such. Back then it would have been a civil engineer who knew how to use soil in design and construction.

It came into it’s own in the early 1900s when an engineer by the name of Karl Terzaghi studied soil and it’s physical properties and developed analytical procedures for using it with steel and concrete in design and construction. Terzaghi is considered the Father of Soil Mechanics.

The soils beneath a site in Canada change as we walk across the site because the glaciers deposited different types of soils in different places 10,000 to 15,000 years ago. (Ref. 3) Farther south the soils result from the weathering and breakdown of the bedrock formed 1,000,000s of years ago. If the bedrock varies from place to place the resulting soils – residual soils – will vary too.

I’ve seen this in my engineering work with glacial soils in Canada and the U.K. and residual soils in the Bahamas and Australia.

Geotechnical engineers are interested in physical properties like the size and gradation of the soils – whether clay, silt, sand or gravel, or some combination – and the strength and compressibility of the soils.

They’re particularly interested in the bearing capacity and settlement characteristics of soils supporting foundations, the drainage properties of soils, and a soil’s susceptibility to slope failure, like along our highways.

(Bearing capacity is a soil’s ability to support the weight of a foundation. Soil settles or compresses when it’s doing this)

Analytical procedures have been developed by engineers like Terzaghi to use the physical properties of soil in design and construction in much the same way that the physical properties of steel, concrete and wood are used.

Understandably, considering the recent flooding, and the mudslides and landslides in British Columbia, geotechnical engineers are even more interested in preventing or avoiding these failures in soil when drenched with rain.

***

Soil is everywhere beneath our feet and geotechnical or soils engineers – dirt doctors to some of our fellow civil engineers when they take a poke at us – are interested in everything to do with soil as a building material.

After years of engineering experience, I know it’s a simple building material once you pay attention and don’t ignore it. Google “What is geotechnical engineering, Wikipedia” and you will get a wealth of information, some quite technical. There’s a listing of some of this information in the Appendix. But really, it’s fairly simple.

Geotechnical engineers have well developed investigative and testing procedures to learn what’s beneath your feet on your building site and how to use it in design and construction.

If there’s an Achilles’ heel, observation and experience are important in the practice of geotechnical engineering. This is because geotechnical engineering relies on the semi-empirical science of soil mechanics.

Well experienced geotechnical engineers have been on site often and got their hands dirty and mud on their boots. Those who haven’t are in peril like the people who ignore soil during design and construction.

References

  1. What is civil engineering? Posted October 15, 2021
  2. What is forensic engineering? Posted September 28, 2021
  3. Sandford, R. W., The Columbia Icefield, Attitude Publishing, Banff, Alberta, Canada 1993

Appendix

A. A list of civil engineering specialties might look like the following to those of us who live in or near a city, town or village:

  1. Structural design engineering
  2. Foundation
  3. Geotechnical
  4. Construction engineering
  5. Highway engineering
  6. Environmental (formerly sanitary, water supply and storm water collection
  7. Forensic engineering

B. Types of structures in the built environment that a geotechnical engineer in which a geotechnical engineer might be involved:

  1. Foundations
  2. Lateral earth support structures
  3. Earthworks
  4. Geosynthetics

C. Some important properties of soils used by geotechnical engineers …

  1. Unit weight
  2. Grading
  3. Porosity
  4. Void ratio
  5. Permeability
  6. Compressibility
  7. Shear strength
  8. Atterberg Limits (Liquid limit, Plastic limit, Shrinkage limit)

D. These physical properties are affected by four main factors:

  1. Predominant size of the mineral particles
  2. The type of mineral particles
  3. The grain size distribution
  4. The relative quantities of mineral, water and air in the soil matrix

***

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada December 21, 2021. ejorden@eastlink.ca)   

Mudslide Zone!

I’m sad at the thought of all those lives lost and people being flooded out in British Columbia. Also the estimated 2,000 farm animals drowning; they got feelings and get scared too. I saw fear in the face of one of my Golden Retrievers one time when attacked by a German Shepard. It was an eye opener.

The flooding and the mudslides didn’t have to be such a surprise.

The flooding at Sumos Lake in B.C. was predicted by the Indigenous people when their land was taken over by farmers in the 1940s. (Ref. 1) A prediction based on millennium knowledge of the land.

The location of potential mudslides could have been predicted too – if you had talked to a geotechnical engineer or a surficial geologist.

Surficial geologists map the different types of soils in an area as deposited by the glaciers many 1,000s of years ago. Eastern Canada has been mapped completely. I’m sure also much of Canada and British Colombia. The data is readily available and easy to understand.

The soils beneath and near the site of a proposed road or bridge – like those washed out – would normally be determined before design and construction. This is standard engineering practice for all structures in the built environment.

The geology maps tell the type of soils and the contours on topographic maps tell the steepness of slopes in the soils – in jargon free language. Maybe a little high school math is needed.

Geotechnical engineers analyse the physical properties of these soils and how strong and stable they are when used or found in different ways. This can include the stability of natural slopes alongside a highway.

The cause of mudslides is understood well enough that signs could be put up to alert a driver – like, “Mudslide Zone“. Signs similar to, “Construction Zone“.

The cause has everything to do with the type of soil, the natural slope of the soil surface, and water. Take out the water – the trigger – and the land and mud will stay put, as it has for 1,000 of years – unless shaken by an earthquake. Water increases the weight of the soil on the (mud) sliding surface and water decreases the frictional resistance of that surface – like in high school physics.

Geotechnical engineers and surficial geologists can tell you were to put the Mudslide Zone signs. Drivers don’t need to be surprised and some swept away. Farm animals don’t need to drown if we listen to Indigenous people.

References

  1. Hughes, John M., PhD, Vancouver, Personal communique, November 2021

***

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada November 21, 2021. Updated November 24, 2021 ejorden@eastlink.ca)   

The tiny culprit in a flooded basement

I recently investigated the cause of a wet basement in a house. A 3/4 inch deep layer of water appeared on the floor at the rear of the basement. And kept appearing after vacuuming and mopping up day after day. At the end of the day, I was surprised at the cause of the flooding.

I took the right approach and looked at all possible causes based on the construction of the basement, and the appliances and equipment in each room. I followed a work breakdown structure (WBS) common in project management and not unlike differential diagnosis in medicine. (Ref. 1)

Basement Construction

The two story, 38 year old house has a completely finished basement. There is an open living area at the front 2/3 of the basement, a computer room and library at the right rear and a laundry room at the left rear. The laundry room is tiled, the other rooms carpeted. The concrete basement walls, footings and some of the pipework are all hidden from view.

The 3/4 inch depth of water was seen on most of the tiled floor in the laundry room. The carpet in the computer room and a short distance towards the front of the open living area was soaking wet.

The house is on sloping ground that drains surface water away from the basement so an easy call during my investigation and no problem there.

A complicated structure

My investigation wasn’t helped by the fact that a basement is one of the most complicated structures engineers must deal with and one of the least glamourous. (Ref. 2)

  • It’s a structure in it’s own right
  • It’s the support for the structure above
  • It’s reliant on the awkward ground beyond and beneath the basement for foundation support and a good life
  • It must deal with the fickle groundwater (the water table) surrounding and beneath the basement
  • It’s got a complicated drainage system
  • You design, construct and investigate basements based on experience and observation (empiricalism) – there’s not a lot in the engineering design and construction handbooks
  • You can’t see much; it’s all buried in the ground

Contractors are happy as clams when they get construction out of the ground. Engineers too. Owners wish there was no such thing as a basement because of the disproportionately higher cost.

Drainage of well built basements

Well built basements are designed and constructed with a layer of free draining soil beneath the concrete floor – a drainage blanket. The layer of soil drains to a pipe – weeping tile – that runs along and just outside the footing. The bottom of the pipe – the invert – is at the bottom of the footing.

The basement walls are backfilled with soil that also drains to the weeping tile. The surface of the backfill slopes and drains away from the basement walls. The weeping tile drains all the water off the property from the drainage blanket and the backfill.

Laundry room floors in well built basements slope towards a floor drain connected by a pipe to the weeping tile – in case water is spilled on laundry day. This is the reason the depth of the flood water in this basement actually varies from zero to 3/4 inches.

Floor drains have a back flow valve that closes after water on the floor drains. The valve prevents water in the ground flowing up the pipe and onto the floor. This can happen when the water table rises.

Why didn’t the water on the floor flow down the floor drain? A good question. Possibly because the floor drain needs some maintenance. Or, the water table is just below the underside of the basement floor – this happens at times.

In general, a complicated drainage system for a complicated structure that can’t be seen, and sometimes gets the short end of the stick during basement design and construction.

What did I investigate?

The following is like a work breakdown structure (WBS) in project management. It’s an identification of the tasks that must be carried out to complete a project. The project in this case is determination of the cause of the 3/4 inch flood. (Ref. 3)

  1. Check that water valves and taps are shut off. The basement laundry room did not have main water shut off valves to the washing machine and wash tub so no problem there. The tap in the laundry tub was turned off, and was kept that way during my investigation.
  2. Note the location of the water on the floor. Part of the reason for locating the water in detail was to eliminate the cause of the flood as due to water getting in from the outside. This happens at the contact between the bottom of the concrete basement walls and concrete floor. Water was located on the tiled laundry room floor as far as the left, right and front walls. It stopped short of the rear concrete basement wall which was encouraging. The floor was damp near the electric water heater in the right rear corner of the laundry room. This was similar to the edge of the water everywhere in the laundry room. This threw me off at the beginning of my investigation. The water returned in the laundry room after it was vacuumed up different times over the next few days. The carpet in the computer room was soaking wet out to all the walls. The carpet in the rear one third of the living room at the front of the basement was soaking wet too. It was difficult to see in the computer room if water was getting in at the contact between the basement wall and the carpet covered floor, so I kept going.
  3. Examine exposed concrete basement wall and floor and the pipe work in the left, rear corner of the laundry room. I did that and everything was dry as a bone. Nice to see.
  4. Examine the electric water heater. I checked the water heater periodically during my investigation. The water on the floor below was similar each time to that elsewhere in the laundry room at the outer limit of the 3/4 inch depth of water. Sometimes I saw a drop of water at the drainage tap at the bottom of the heater – like condensation. Other times I didn’t. The drop of water didn’t raise any alarms.
  5. Remove the carpet to expose the floor and any pipes. I removed the carpet from the floors in the computer and living rooms and did not see any pipes at the bottom of the walls. I saw the water on the computer room floor with the edge extending near the front, rear and right walls, and under the left wall common with the laundry room. But no water on the floor in the living room. I concluded – an easy call – that the wet carpet in the living room was due to capillary action from the soaking wet carpet in the computer room.
  6. Monitor the water in the floor drain after fixing the back flow valve open. I noted that the level of water in the drain occasionally dropped to about 2 inches below the floor. So, the water on the floor from somewhere was slowly draining away through the floor drain. The 2 inch level below the floor was suggestive of a natural water table just below the floor.
  7. Examine the bottom of all walls in the laundry and computer rooms for leaks from outside the basement. I examined the bottom of the walls but did not see any leaks from outside the basement. So, the water on the floor was not getting in from outside the basement. An important finding.
  8. Vacuum the water off the floors after the carpet was removed. I vacuumed the water off the floors several times and noted the same area was covered when it returned after about a day, including near the water heater. And as noted above it was sometimes draining away through the floor drain. I checked the water heater again. A drop of water continued to be occasionally seen at the tap on the heater. I felt the water on the floor below the tap as I occasionally did. It was warm one time. Other times it was cool like the concrete floor.
  9. Collect the drops of water in a saucer set below the tap on the water heater. I did this a couple of times when I saw drops of water and noted that the saucer quickly filled with water. Hmmmm?
  10. Research operation and performance of water heaters I interviewed a home owner I knew who had an electric water heater and sales people in stores that sell electric water heaters. I learned that water heaters must be drained and cleaned on a regular basis – a few months to a few years depending on who you’re talking to, whether or not you’re on city or well water, and what’s going on in your neighbourhood, e.g., construction – and also that they sometimes leak. That was a surprise – a leaking, glass lined, steel encased electric water heater. But not a surprise for long because water heaters are drained through a pipe that passes through a hole cut in the steel, and water has corrosive elements that love cut steel edges and surfaces. Bingo!
  11. Conclusion: Recommend replacing the water heater I recommended replacing the water heater, including a drip pan beneath the heater – missing at this residence in the past – and monitored it’s installation. I advised draining the heater on a regular basis in future. The culprit – the rogue drop of water – hasn’t been seen for weeks and the basement floor is dry.
  12. Remove the damaged gyproc drywall from the bottom of the walls to better examine the condition of the inside of the walls The drywall softened and swelled for several feet above the floor when flood water was drawn up by capillary action from the floor. This engineering investigative task has been postponed pending monitoring the floor for flood water over time.
  13. Video the floor drain pipe I considered snaking a video camera down the drain pipe to see if there is anything in the pipe that could prevent water draining. This could consist of sediment that can collect over time or a collapsed pipe. The need for this task will be evaluated after the water level in the floor drain has been monitored over time.
  14. Replace the floor drain with one fitted with a suitable back flow valve. The back flow valve needs to be sensitive – open and close – under very low hydraulic heads, like a very few centimetres. The need for this task will be assessed pending the outcome of videoing the floor drain pipe and noting how well the drain works over time.
  15. Drill observation holes in the concrete floor to check for a water level beneath the floor. The need for this task will be assessed pending the outcome of videoing the floor drain pipe.

Lessons learned

  1. Suppress your expectations at what might be the cause of a problem, and what might not be a cause because its so tiny and inconsequential. Continue to go the project management, work-break-down route.
  2. If a drop of water can wear down a rock over time, or change rock into residual soil like in Australia, it can flood a basement.

References

  1. Differential diagnosis in medicine and forensic investigation, and soft, initial thoughts on cause. Posted December 20, 2019
  2. Swinton, Michael C., and Kesik, Ted, Performance Guidelines for Basement Envelope Systems and Materials, Research Report 199, October 2005 pp 185 NRC-IRC and the University of Toronto
  3. Kerzner, Harold, Ph.D, Project Management. A systems approach to planning, scheduling, and controlling. 8th edition, 2003, John Wiley & Sons, Inc., New Jersey

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada November 15, 2021 ejorden@eastlink.ca)   

Raking liability aside when you rake the leaves

I’m enjoying the fall colours Down East like everyone else. The forest and the falling leaves, and those that end up on the path where I walk my dogs are something else. The dappled sunlight in the forest is a special sight especially after a light rain when the leaves are glistening in the sun. What’s not to like?

But it hit me recently when I had Rosie and Lily out for their morning pee run that these wet leaves on my sloping lawn are slippery – wet from rain not dog pee. I was a bit surprised.

Later when I was walking down the timber stairs from my deck the same thought occurred. There weren’t many leaves on the stair but when I slid my boot across the few, I could see that a lot of leaves might reduce the skid resistance of the timber enough to cause a slip and fall. No question a lot of wet leaves on a sloping, wet lawn would reduce the resistance. I’m careful now when I walk down a wet slope in a field overlooking Settle Lake in Halifax where my dogs run around like crazy.

How is this relevant to the purpose of this blog site “…to explain the nature and methods of forensic engineering and expert services”?

Well, who would have known wet leaves could cause someone grief? And is there a responsibility to rake the leaves everywhere in public places to reduce the liability?

It’s relevant because some might wonder, can you test the skid resistance of a leaf covered timber stair or a wet, leaf covered lawn? You certainly can.

I tested the skid resistance of the wet floor in a dry sauna where a woman had slipped and fallen using the skin from a pig’s belly. The skin is very similar to that on a person’s foot. I couldn’t use the woman’s foot and cause her to slip and fall again. Although I did think briefly about how I might have used her foot.

If you can measure it you can deal with it. (Refs 1 to 4) I believe you can measure everything including the frictional resistance of wet, leaf covered surfaces, and even the forest floor. Sometimes the measurements are rough but rough is better than nothing.

So, sweep those stairs, rake that lawn, and take care where you walk in public places.

References

  1. Osmond, Jack, “If you can measure it, you can manage it”, As quoted several years ago
  2. If you can measure it you can manage it, even if it’s a real mess like a car or truck accident. Posted June 23, 2016
  3. “Taking the measure” – forming an opinion of the cause of a fatal motor vehicle accident. Posted February 15, 2016
  4. “If you can measure it you can manage it” and do thorough forensic engineering and cost effective litigation. Posted June 18, 2015

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada October 25, 2021 ejorden@eastlink.ca)   

What is civil engineering?

I’m a civil engineer by degree, but what exactly am I? What do civil engineers do? This question came to mind as I was recently drafting the blog, “What is forensic engineering?”. I thought, what would I say if asked? I was spooked because its many things. Where do I start?

Why not some fascinating history?

It’s the oldest engineering profession dating back to the first time someone placed a roof over his or her head or laid a tree trunk across a stream to make it easier to get across, and made certain these structures were strong enough. Then cut a road through the forest between the stream and the roofed-over abode. (Ref. 1)

It’s old if you just date it from the time of the Great Pyramid at Giza – about 4,600 years ago – the only one of the seven ancient wonders of the world that still survives. There are no records but the mathematical patterns of the structure and the internal passages suggest advanced planning and engineering – good civil engineering.

I studied construction of the Pyramid one time. The Pyramid hasn’t failed but a basic task in forensic engineering is learning how a structure was designed and built in determining the cause of a failure. Forensic archaeology is a field of study. (Ref. 2)

The Pyramid is a classic example of structural, foundation and geotechnical engineering – civil engineering disciplines – that had to accommodate differential settlement across the base of the Pyramid.

There’s a great weight on the foundation soils in the centre of the Pyramid, and lots of foundation settlement there. There’s little weight and settlement at the edges of the Pyramid. The result is differential settlement of the Pyramid’s foundation.

Hmmmm, why no cracks in the sloping sides of the Pyramid – a normal result of differential settlement? The reason is a simple, civil engineering solution – and a blog topic for another day.

Come forward to the 18th century and civil engineering is still quite old. Like said, it’s been around since the beginning of human civilization, since the appearance of Sapiens (Ref. 3) but it was not until more recently that the term civil engineering was coined to refer to the design and construction of civilian infrastructure. This as distinct from military infrastructure.

John Smeaton was the first person to call himself a civil engineer. His design of the Eddystone Lighthouse near Cornwall, England, 1756 to 1759, was based on his construction experience and thorough research – civil engineering.

The Institution of Civil Engineers was founded in London, England in 1818, and the profession was formally recognized in 1828. In time, comparable professional associations were founded in Canada, the United States, Australia and elsewhere in the world.

I also understand that a distinction was made between an engineer and an architect about this time or not too long afterwards. They were seen to be one and the same till then.

***

Civil engineering is not unlike an umbrella profession for a number of specialties that have developed over the years – 17 by my last count. (see Appendix) It wasn’t long till specialties were recognized in the planning, design and construction of the structures that comprise the infrastructure – the built environment – of our villages, towns and cities.

Specialties in the beginning like structural, foundation and geotechnical engineering. Soon highway engineering to get us from one village to another, then water supply engineering, and, of course, sanitary – now environment engineering – to get rid of waste and dirty water.

And because components of structures break and don’t work right, and structures collapse and fall down, and accidents happen and people get hurt, forensic engineering came to be.

At some point, mechanical and electrical engineering appeared outside the civil umbrella dealing with things that move, and design and construction involving more than basic electricity

A list of civil engineering specialties might look like the following to those of us who live in or near a town or village:

  1. Structural design engineering
  2. Foundation design
  3. Geotechnical
  4. Construction engineering
  5. Highway
  6. Environmental (formerly, sanitary)
  7. Water supply
  8. Forensic engineering

For example, Structural engineers design the steel, concrete and timber to support the structure. Foundation engineers design the footings and piles to support the structure. Geotechnical engineers find a layer of soil at the construction site that is strong enough to support the foundations that support the structure. Construction engineers build it. If anything goes wrong, Forensic engineers fine out why.

You take a degree in civil engineering and study a little of each of the above, then work and gravitate to one or the other and study more. I got my first degree in civil then moved onto geotechnical then to forensic.

***

What we see on a day to day basis is pretty common on the East Coast, as elsewhere – like, low and high rise buildings, houses, roads and sidewalks, power lines, propane tanks, wharves, water pipes, sewage pipes, storm drainage pipes and highway bridges – all involving a civil engineering specialty of one kind or another.

But get away from the mundane urban scene and civil engineers have designed and constructed some impressive structures since the Pyramid. In fact, more impressive than the Great Pyramid if I may be so bold.

These are reflected in the list in the Appendix as identified by the American Society of Civil Engineers (the list has an “only in the U.S. of A. tone” as noted in a postscript to the list)

I was quite taken during my research for this blog to learn that some suspension bridges are designed with a fin to control the effect of the wind – just like the fin on a whale to control the effect of water. One bridge failed out west one time because the wind made it wobble and shake too much.

***

What is civil engineering? You are surrounded by it from dawn to dusk and from birth to when you take your final leave.

You do the following on any given day in between, regardless your civil engineering specialty, and how mundane or impressive the structure:

  • Collect data on the structure and it’s purpose,
  • Analyse the data,
  • Design your part of it according to your specialty beneath the umbrella to perform as intended
  • Then ensure it’s constructed as designed.

Boring at times, as in same old same old, but where would the built environment be – the civilian infrastructure – without civil engineers?

References

  1. Google, Doctor. Thanks to Dr. Google for some comment and insight on the blog. October, 2021
  2. Catling, Christopher and Bahn, Paul, The Complete Practical Encyclopedia of Archaeology, (see page 226) Annes Publishing Ltd 2013, England
  3. Harari, Yuval Noah, Sapiens, A Brief History of Humankind, McClelland & Stewart, Canada, 2014

Appendix

Civil engineering is an umbrella discipline for engineering specialties like the following:

  1. Planning
  2. Design engineering
  3. Construction engineering
  4. Structural engineering
  5. Foundation engineering
  6. Geotechnical engineering
  7. Forensic engineering
  8. Highway engineering
  9. Bridge engineering
  10. Water resource engineering
  11. Environmental engineering (formerly, Sanitary)
  12. Hydraulic engineering
  13. Municipal and urban planning
  14. Coastal engineering
  15. Tunnel engineering
  16. Earthquake engineering
  17. Survey engineering

The members of the American Society of Civil Engineers (ASCE) ranked the 10 greatest civil engineering achievements as:

  1. Airport design and development
  2. Dams
  3. Interstate highways
  4. Long span bridges (e.g. suspension bridges)
  5. Rail transportation
  6. Sanitary land fills/solid waste disposal
  7. Skyscrapers
  8. Waste water treatment
  9. Water supply and distribution
  10. Water transportation

Postscript: I think they messed up in not including tunnels like those through the Alps and the one beneath the English Channel from England to France – civil engineering extroedinaire.

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada October 15, 2021 ejorden@eastlink.ca)   

What is forensic engineering?

I saw reference in a magazine to a student who expressed interest in forensic engineering. (Ref. 1) I wondered what I would tell her if asked. I came up with the following after a bit of thought:

  1. Describe the work and give a few examples
  2. Stress the importance of being thorough and objective!
  3. Note, of course, that forensic engineers serve the judicial process
  4. But also note that most disputes settle out of court, fortunately
  5. Get ready to be surprised at the great number of different categories of experts – many 1,000s
  6. Stay in your sandbox if you do get into forensic work!
  7. Think about where you might practice in future
  8. Get a basic degree
  9. Get experience

For sure, define the work. Remind them that engineers, in general, apply science and mathematics to make materials and the energy in nature useful to people. Materials like steel, concrete, wood, plastic, water, and soil and rock.

Forensic engineers, in particular, apply science to determine the cause of problems in the built and natural environments. To figure out what sometimes goes wrong.

Give examples, like why a building or a tank collapses, the ground sinks, a bridge fails, a crane falls, the land slides, a nail gun misfires, a property floods or is contaminated, a road washes out or a person slips and falls.

At the same time remembering when doing this that our clients have budgets, time frames and interests that are sometimes at odds with a forensic expert’s need to be thorough and objective.

When a dispute arises from a problem and the matter goes to court, a forensic engineer serves the judicial process even though the engineer has been retained by one of the parties to the dispute. Hence the adjective forensic meaning ‘belonging to, used in, or suitable to courts of law or to public discussion and debate’. (Ref. 2) Fortunately, more than 90% of disputes are settled out of court.

A student should note the different engineering disciplines that identify the cause of problems. For example, civil, mechanical, electrical, bio-mechanical and environmental. Also note associations like the American Society of Civil Engineers and others in the US, Canada and elsewhere representing the interests of these disciplines.

S/he should research the different categories of forensic expertise that have developed – many 1,000s – by visiting a site like www.seakexperts.com. (also see Ref. 3) SEAK, Inc. is an expert training firm in the U.S. that offers courses on expert work. Expert Communication, Inc at www.expertcommunications.com is another in the U.S. that guides forensic experts.

Knowing the different disciplines, and the multitude of categories, will help a student know what specialty to follow in forensic engineering, if their interest continues to develop. It will also help you to stay in your sand box when practicing – do what you’re qualified to do, nothing else.

I think a student must get a basic degree in engineering then practice for a while. The way forward will then come into focus and the additional studying and courses needed.

I searched a little on line for graduate degrees in forensic engineering. I saw courses mentioned but no degrees during my quick search. I’m certain there is something out there. A student should evaluate carefully what is offered and it’s recognition by the public.

I saw courses offered in forensic archaeology in the U.S. and England in a practical encyclopedia on that field of study. (Ref. 4. A good read on engineering?) For certain there are comparable courses in forensic engineering, and maybe degrees.

Skimming through the encyclopedia I was struck by how the basic detailed investigation in forensic archaeology, and the methods used, echoes that in my work, and I’m sure in other disciplines. Sounds boring but here goes: Gather data. Analyse data. Draw conclusions. Form opinion. Repeat, if additional data comes in and your initial hypothesis as to cause must be modified.

Thinking about where you might practice will be important. The nature and methods of forensic engineering will vary some. For example, the 256 blogs at www.ericjorden.com/blog give some indication of the nature and methods of forensic engineering investigation and expert services on the East Coast of Canada.

Soon, experience will present to you as important in forensic work. There are many engineers with basic degrees, no more – but lots of experience – that are well regarded in their field. There are also many highly regarded experts in the categories identified by SEAK, Inc. that have no university degrees at all – just lots and lots of experience.

Still, if you have an interest in forensic engineering, a basic degree won’t hurt. And it will enable you to earn a living while you get experience.

References

  1. The Engineer, Nova Scotia’s Source for Engineering News, Summer/Fall 2021
  2. McGraw Hill dictionary
  3. Super experts: Only in the U.S. of A., you say? Posted August 24, 2021
  4. Catling, Christopher and Bahn, Paul, The Complete Practical Encyclopedia of Archaeology, 2013 Hermes House, Leicestershire, UK info@anness.com (This looks like a good read for insight on engineering through the millennium, sans computers and construction equipment)

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada September 28, 2021 ejorden@eastlink.ca)   

Real and virtual visual site assessments

A visual site assessment – either Real or Virtual – is a valuable task in the investigation of a personal injury or a failure in the built environment. I explain this in the Bundle of Blogs below that I posted in the past. This type of assessment is particularly valuable during COVID-19.

In a Real assessment, the forensic expert does the following tasks:

  1. Gets briefed by the client
  2. Reads documentation on what happened
  3. Goes to the scene of the personal injury or failure,
  4. Examines the exposed surfaces at the site
  5. Notes what’s there and what’s not
  6. Takes some measurements
  7. Also some photographs
  8. Perhaps gets video from a drone
  9. Gets “calibrated” to the site (Ref. 1)

S/he does not do the following that come later if required:

  1. Look below the surface
  2. Take things apart
  3. Do intrusive field testing, or
  4. Laboratory testing

What is done during the Real assessment process is not too much different from the SOAP (Subjective Objective Assessment Plan) and Differential Diagnosis processes in medicine. (Refs 2, 3)

A lot of data and evidence is gathered this way, sometimes enough to reason to a conclusion and form an opinion on cause sufficient to resolve a dispute or settle a claim.

A Virtual assessment – sans site visit – is also good, and sometimes enough. If it has a shortcoming, the expert doesn’t get “calibrated” to the site as well as he might. Nor get his hands dirty and mud on his boots. (Ref. 4)

I’ve done several virtual assessments including one a few months ago at the scene of a trip and fall accident. Others were of retaining wall failures, a bridge collapse, several building collapses and a trench cave-in.

One assessment resolved an 11 year dispute after a four month forensic investigation. A person was injured by ice falling off a structure. In hindsight, that visual site assessment was half real and half virtual – I examined the exposed surfaces with binoculars from across the street.

At the time of this investigation I got insight into the formation and risk of ice on structures during a ski trip to Mont Comi on the Gaspe Peninsula. The penny dropped as I came and went from the ski lodge. Ice formed at the eaves trough till it got too heavy and fell off. Signs warned skiers of this. I also saw ice on buildings during a visit to my daughter’s horse farm in Maine. Forensic engineers are working even when they’re not.

***

In the following, I’ve listed a few recent blogs on Real and Virtual visual site assessments that are particularly relevant in COVID-19 times. I’ve posted others in the last nine years but the following are enough.

At the end of the day, while a visual site assessment, real or virtual, is often enough to resolve a dispute or claim, there are situations where field work must be carried out.

A Bundle of Blogs: The value of Real and Virtual Visual Site Assessments

  1. How do you carry out a forensic investigation during a pandemic? Posted January 8, 2021 The blog notes the value of plain old engineering experience. But, when coupled with a virtual visual site assessment, invaluable and more reliable still. Three engineers found the same cause of a building collapsing, two based on experience alone. The third based on experience plus a virtual visual site assessment.
  2. COVID-19 and forensic engineering investigation. Posted May 7, 2020 It struck me one morning while walking my dogs that forensic engineering investigation is not prevented by COVID-19.  Experts often work alone as principal investigators conferring with other specialists as needed.  Many of the most experienced experts are sole practitioners.  We already “work from home” in a sense and have for years.
  3. COVID-19 and an initial forensic task a.k.a. a visual site assessment, sans social distancing. Posted June 1, 2020 The blog reminds us that the visual site assessment is carried out by a lonely expert whether on site or virtually. Social distancing is not an issue. It also reminds us that it’s an essential task that should be done before the dust settles at the site of a failure or accident.
  4. Get on site and do a forensic visual assessment before COVID-19 returns. Posted September 10, 2020 This seems a bit of a joke this day as a fourth wave threatens us. But the blog does contain nice comment on how document review, virtual site assessment and on-scene assessments work together to yield a lot of data and evidence on the cause of a failure or accident.
  5. Can you “calibrate” a forensic expert? Posted June 23, 2020. This is a good read, a bit of an eye opener as to what happens to an expert when s/he goes to a site and collects hard data. An expert does get “calibrated” to the scene of an failure or accident during a visual assessment. The process also happens to some extent during a virtual assessment.
  6. Counsel: Your case benefits when you visit the scene of a personal injury accident or engineering failure. Posted April 30, 2016 In a sense, this was a visual site assessment by counsel in a slip and fall case that paid dividends. He went to the accident site to watch me carry out skid resistance tests. Management later cancelled further expert work including submission of a report on the skid testing because the firm underestimated the cost of expert services. All that my client had to argue his case was his viewing of the field testing, photographs he had taken and my verbal comments on the results as we drove back to the city.
  7. “Technical” visual site assessments: Valuable, low cost, forensic engineering method. Posted September 4, 2012 The blog explains that the visual site assessment is a basic initial task in a forensic investigation. Sometimes it’s all that is necessary in the gathering and analyzing of data on the cause of an accident or failure.

Examples of Real and Virtual Visual Site Assessments

  1. My personal slip, trip and fall accident. Posted September 2, 2021
  2. Why did the four story building collapse during construction in London, Ontario? Posted December 31, 2020
  3. What can you get from a virtual site assessment about the cause of a leaning retaining wall? Posted November 13, 2020
  4. What can you get from a virtual visual examination of an accident scene. Posted August 28, 2020
  5. Wind, construction crane and inadequate cross-bracing caused Edmonton bridge failure: An initial hypothesis. Posted March 27, 2015
  6. Falling roof ice injures man. Posted January 18, 2013
  7. Gabion retaining wall collapse results in litigation. Posted February 9, 2013

Related to the blogs in the Bundles above

  1. The reliability of an educated guess on the cause of a failure or accident. Posted October 22, 2020.
  2. Where does an expert’s initial hypothesis come from? Posted February 25, 2019. Updated March 18, 2019

References

  1. Can you “calibrate” a forensic expert? Posted June 23, 2020
  2. Using SOAP notes in forensic engineering investigation. Posted February 6, 2014
  3. Differential diagnosis in medicine and forensic investigation, and soft, initial thoughts on cause. Posted December 20, 2019
  4. An expert’s “dirty hands and muddy boots”. Posted December 20, 2013

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada September 14, 2021 ejorden@eastlink.ca)