Keeping “Animation” simple was one good idea that I got from the Zoom meeting six of us had on animation in forensic work.

Animation is a procedure that brings to life the scene – in model form – of a failure in the built environment or an accident on a highway. It relies on the same basic principles and methods that produce the funny cartoons in TV ads. (Refs 1, 2 and 3)

However, there is a risk of mistaken or deliberate misuse of animation in an expert’s work. The risk was thought to be small, but you should read the animation software sellers’s promise of “building a solid case” to know it’s there. The promise will appeal to some.

Keeping it simple reduces the risk of mistakes or mischief. If the animation is submitted as evidence, it also helps parties to the judicial and dispute resolution processes better understand what happened to cause the failure or accident.

Simple is less entertaining and fun to watch but more focused on cause. Mistakes and mischief are also more likely to be found out.

I thought it would help if you saw some simple animations to learn what to look for in your expert’s report. The following were suggested by my colleagues (see Appendix) as examples of the simple and the complicated, the good and the bad. I highlighted in red what I thought were simple animations:

(Gremlin alert!! I’m sorry, a gremlin got in the works. You must copy the links for #1 to #15 below longhand then type in Google to see the animation. I tried to fix the problem but got nowhere. The links highlighted in red are worth the longhand effort. The links for #1 to #9, way below, work okay; just click on them and away you go)

1. Favorite Accident Reconstructions https://www.youtube.com/watch?v=JJHZ5QcDe1o
2. Pedestrian Night Accident Animation and Laser Scan https://www.youtube.com/watch?v=cPluPmAabjE
3. 3D Laser Scan Crash Visualization https://www.youtube.com/watch?v=rM5ncfXkFsM
4. PC-Crash 12.1 available – VR video https://www.youtube.com/watch?v=jNJyWOHPOxU&list=PLeVcNHSgLdvnmL-DciU1hopWUO6iQlFCp&index=13
5. PC-Crash 12.1 – 360 VR driver’s perspective video https://www.youtube.com/watch?v=OH-QkvDMio0&list=PLeVcNHSgLdvnmL-DciU1hopWUO6iQlFCp&index=12
6. LiDAR vs Photogrammetry Data Outputs for slope stabilisation works https://www.youtube.com/watch?v=tLNB2NG4Gzk
7. Photogrammetry vs RGB-Fused-LiDAR on a Phoenix System https://www.youtube.com/watch?v=5CyOX7IsQNM
8. Truckee River Flume Photogrammetry vs Lidar https://www.youtube.com/watch?v=HLlxEcDFYIQ
9. Drone LiDAR vs Photogrammetry | Epic Stadium 3D model https://www.youtube.com/watch?v=_RNiWTJw3KA
10. Cool https://www.youtube.com/watch?v=dnZ4I3FFnUI
11. Princess Di https://www.youtube.com/watch?v=86eJs-ULapw
12. Crush https://www.youtube.com/watch?v=lgOpSh8eTPw
13. Day to night trucks https://www.youtube.com/watch?v=JNsBYyUb8q0
14. Jenner https://www.youtube.com/watch?v=F9hA8D4k2_4
15. Gyro https://www.youtube.com/watch?v=8c1lF6uEmu

1. Favorite Accident Reconstructions https://www.youtube.com/watch?v=JJHZ5QcDe1o
2. Pedestrian Night Accident Animation and Laser Scan https://www.youtube.com/watch?v=cPluPmAabjE
3. 3D Laser Scan Crash Visualization https://www.youtube.com/watch?v=rM5ncfXkFsM
4. PC-Crash 12.1 available – VR video https://www.youtube.com/watch?v=jNJyWOHPOxU&list=PLeVcNHSgLdvnmL-DciU1hopWUO6iQlFCp&index=13
5. PC-Crash 12.1 – 360 VR driver’s perspective video https://www.youtube.com/watch?v=OH-QkvDMio0&list=PLeVcNHSgLdvnmL-DciU1hopWUO6iQlFCp&index=12
6. LiDAR vs Photogrammetry Data Outputs for slope stabilisation works https://www.youtube.com/watch?v=tLNB2NG4Gzk
7. Photogrammetry vs RGB-Fused-LiDAR on a Phoenix System https://www.youtube.com/watch?v=5CyOX7IsQNM
8. Truckee River Flume Photogrammetry vs Lidar https://www.youtube.com/watch?v=HLlxEcDFYIQ
9. Drone LiDAR vs Photogrammetry | Epic Stadium 3D model https://www.youtube.com/watch?v=_RNiWTJw3KA

References

1. Animation in Forensic Work: Use and Misuse. Posted January 12, 2022
2. Telling it like it is, in forensic expert report writing. Posted January 27, 2022
3. What did we get from a good talk on animation in forensic work? Posted February 27, 2022

Appendix

The animation links were suggested by Adam Cybanski, Gyro Flight & Safety Analysis, Inc, Kemptville, Ontario, Stuart Smith, C. R. Tyner and Associates, Dartmouth, Nova Scotia, and Ken Zwicker, Atlantic Crash, Pentz, Nova Scotia. These chaps specialize in traffic accident reconstruction and related fields. They serve as experts when called on.

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

A few days ago, six of us had a free ranging Zoom talk about using animation to determine the cause of a traffic accident. It was prompted by questions like the following:

1. Is there a problem using animation in forensic work?
2. What’s the problem?
3. How serious is it?
4. What’s the cause of the problem?
5. How can the problem be fixed?

I learned from the talk that in spite of the mess at the scene of a traffic accident there are reliable methods that experts use to determine the cause. These methods involve modeling and animation software that are input with data and measurements got at the scene.

But, misleading data can also get into the software. It was this fact that prompted one person to suggest blogging about animation in forensic work. (Refs 1, 2) Another suggested a Zoom talk about it. It’s a problem because once the participants in the judicial and dispute resolution processes see a misleading animation they can’t un-see it – the impression has been made.

Participants who might be misled include:

• Insurance claims adjusters
• Civil litigation lawyers
• Judges and jurors
• People involved in alternate dispute resolution
• Injured parties in general

The data obtained during an accident investigation is put into modelling or simulation software that develops an inanimate model picture of the accident scene that includes the vehicles and features involved. Some of the data also goes into animation software connecting this software to the inanimate model making the vehicles appear to move.

Examples of animation:

The cartoon figures you see in TV advertisements started out as inanimate pictures in modelling software. Animation software got the figures moving to amuse and catch our attention – and prompt us to read the advertisement.

The same principles underlie the animation of a traffic accident that helps us understand what happened. Some animations are alarming to watch and not amusing.

You might take a look at the following simple animation depicting an accident from different view points and by the different drivers involved in the accident. It will give you an idea of what I’m talking about. If you are somewhat in awe at what you see then you understand part of the problem with animation in forensic work:

https://www.youtube.com/watch?v=JFCFNDeoHKA

Talkers at the Zoom table:

• Two traffic accident investigators (Reconstructionists; the name in common use in North America),
• A former accident investigator who now lectures,
• A fourth chap who also investigates failure in general as well as traffic accidents,
• A fellow who animates the results of traffic accident investigations,
• And your’s truly who investigates the cause of failure in the built and natural environments.

Stages followed during an accident investigator:

1. Collect data. Data like published mapping and photography of the site including a Google Earth image and/or drone photography. Walk and visually examine the site. Measure and photograph features at the site, and, Read police reports on the accident.
2. Analyse data. Draw diagrams of the accident site. Place the objects (vehicles) and features associated with an accident on a Google Earth image to produce a land surveyor-type site plan for use in the simulation/modelling software. Model the traffic accident using published software. Animate the model using software to better understand the data and to ‘give it life’.   Add colour, lighting, texture, etc. to the animation software.  Study and note the different causes of the accident as indicated by the individual data. Note the extent to which one cause of the accident is indicated by the bulk of the data.
3. Draw conclusions. Conclude the different causes of the accident as evident in the data and why one cause is more probable than another.
4. Form opinion. Draft opinion on the cause of the accident.
5. Write forensic report Write report in technical English, plain English or a combination technical/plain according to the requirements of the client.

Some questions asked by a traffic accident investigator:

• How many vehicles were involved?
• What kind of vehicles were there?
• Which vehicle crossed into the other lane?
• How did they get the exact positions of all vehicles?
• How many lanes were?
• How big was the shoulder?
• What were the lane markings like?
• Were they worn?
• Were there tire skid marks and where were they located?
• How long were the marks?
• What was the skid resistance along the marks (coefficient of friction in high school physics)?
• Were there pedestrians or other obstructions on the road?
• What was the weather like (clear, rain, snow)?
• What time of time was it (night, dawn, day)?
• What was the visibility like?

You can easily imagine how careful a reconstructionist must be with so much data to collect and input. S/he must know how to use the software correctly, know the correct values to input, and how to correctly interpret the results. There’s no room for error in a forensic investigation when giving an opinion on cause.

• Soft data like visual effects (lighting and colouring) can also be useful if added to the software. But, you’ve got to be careful with this one.

One talker at the Zoom table noted: “I think whether it’s animation or simulation/modelling, the input values need to be shown to be correct, or at least reasonable, for the results to be correct and admissible. My concern is when realistic but unproven graphics such as lighting and colouring are used.  These effects can leave a subconscious impression on a judge or jury that can affect their perspective and judgement.” 

Accurate animation software

Most accident reconstructionists accept that the modelling and animation software programs most frequently used are accurate. These are PC-Crash and Faro Blitz to name two of three or four. Nevertheless, where possible, calculations are checked by hand and input values made certain.

Misusing animation software

It’s also at the modelling and animating stages that inadvertent or deliberate misuse can occur. The talkers at the Zoom table didn’t think the latter was a serious problem.

Still, the software sellers “build a case” promise still rings in my ear, and how that must resonate in the ear of some bad-cat experts.  Google forensic animation and see for yourself. I am comforted by Ruth Corbin’s findings in her excellent pilot study of 152 experts that all experts clearly understand that they serve the judicial process not their client or themselves. (Ref. 3)

Expert reporting in plain, jargon-free English

With so much data/input arising from a traffic accident reconstruction I believe expert reports in plain English are essential for non-technical readers, or at least a summary report.  Animations are so realistic – and in many ways, entertaining like a roller coaster – it’s essential to help readers know what they’re seeing and must focus on.

What did I get from our talk?

1. Animation in forensic work is helpful in resolving disputes, particularly in determining the cause of traffic accidents, but keep it simple.
2. Don’t submit the animation as evidence unless it’s a simple animation.
3. Check the input data. Check the output animation when possible.
4. It’s difficult to correct a false impression taken from an incorrect animation.
5. Modelling and animation software are quite accurate.
6. But remember that the software seller is in business to sell software, and help you “build a case”, as s/he sees it.

References

1. Animation in Forensic Work: Use and Misuse. Posted January 12, 2022. Updated January 20, 2022
2. Telling it like it is, in forensic expert report writing. Posted January 27, 2022
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 (Google this excellent paper and Ruth’s name)

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada, February 27, 2022. ejorden@eastlink.ca)   

I was surprised a day after posting my blog about animation in forensic work – almost like a light coming on – that misinforming the dispute resolution process was the key issue. Or not informing it properly.

Relevant to this issue are bias and also initial impressions taken by non-technical parties to the dispute. Parties like busy judges with a full docket and non-technical backgrounds. (Ref. 1)

Misinforming can include misuse of animation and modelling software and, by omission, not explaining in jargon-free English how the software works and what the expert’s report is saying.

I don’t use this software in my forensic work and learning about it to blog about it was a bit of grind. However, I do write my expert reports in jargon-free English.

If it was a grind for me, I can’t imagine what it would be like for a non-technical client trying to learn something about the software used to solve their problem. It’s important to know what you’re buying – the software and how it was used to determine the cause of your problem – and have this explained in simple English.

Bias in forensic work is an important issue too. There are as many categories of bias as letters in the alphabet – check out what might be called a wheel-of-misfortune (my label) on Dr. Google.

This problem of bias for experts was addressed at a conference in Toronto in 2018. (Refs 2, 3 and 4) Speakers identified (8) eight categories of bias in expert evidence of which two were discussed at length: (Refs 3 and 4)

1. Expectation bias (Anchoring)
2. Confirmation bias (Tunnel vision)

A busy court docket is another important issue, and dispute resolution processes that push for quick decisions. These decisions sometimes end up based on incorrect initial impressions that can’t be removed from the judge’s head. Decisions on technical issues by non-technical people. (Refs 5, 6 and 7)

Conclusions

What’s to be done about these important issues? This is what I think based on my insight a day after posting my blog earlier this month – when the light really came on:

1. The forensic expert must learn how the animation and modelling/simulation softwares are designed, particularly the basis of the designs
2. Learn about the accuracy of the software and what the software seller’s claim of accuracy is based on. How does s/he know?
3. Explain the software and it’s accuracy to the client in jargon-free, non-technical language
4. Alert clients to some of the key forms of bias as might show in expert work, both the deliberate bias, and the tricky bias that creeps up on all of us at times
5. Write and submit expert reports in jargon-free, non-technical language, possibly also in technical language – two reports(?)
6. Express concern to the client about problems with a decision maker’s initial impressions, like those of judges, jurors and those involved in dispute resolution.
7. Also our concern that clients will pick and chose from our reports in the best interests of their clients, even though our reports are meant to serve the judicial process thoroughly and objectively.

References

1. Animation in Forensic Work: Use and Misuse. Posted January 12, 2022
2. Expert Witness Forum East, Toronto, February 27, 2018
3. Expert Witness Forum looks at Bias and Other Touchy Subjects in Forensic Work. Posted March 8, 2018
4. Are experts being broadsided by bias unbeknownst to them? Posted April 12, 2018
5. Corbin, Ruth, in discussion on a couple of occasions
6. Capurso (1998), Timonthy J., How Judges Judge: Theories on Judicial Decision Making, University of Baltimore Law Forum Vol. 29: No. 1, Article 2
7. How experts are helping break the expert evidence logjam. Posted April 30, 2018

(There are additional references at the end of some of the above that are also good)

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada, January 27, 2022. ejorden@eastlink.ca)   

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
• Judges and jurors
• 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 figures.

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 for 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, Updated: January 20, 2022. ejorden@eastlink.ca)   

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 bare 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 really 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)   

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)   

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)   

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” that we see everywhere.

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)   

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)   

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)