You can sometimes use a camera to take the measure of important technical issues during a forensic investigation.  And unexpectedly get the answers to your questions quickly and easily as I found out during one investigation.

I was retained by the RCMP a few years ago to determine if a pile of salt on a highway contributed to a fatal motor vehicle accident (MVA) – that was the technical issue.  I did this by carrying out field trials like they do in speed bump research.  These trials determine the effect of different sizes and shapes of speed bump on vehicles travelling at different speeds.

When I started these trials I didn’t know where they would take me except they approximated what took place during the fatal MVA – and involved measuring like engineers do.  There were no neat little formulae, no salt-pile-contribution-determining procedures in text books.  But I had to start somewhere – the way it so often is in forensic engineering investigation.  The end result was surprising in answering the question about the contribution of the salt pile.

I built a test site on a run way at the Shearwater airport like those for speed bump research.  I marked off a traffic lane on the runway the same size as that at the accident scene.by painting a centre line and shoulder lines.  I then constructed a pile of salt in the lane the same shape and size as that at the scene.  My tests would involve driving the vehicle in this lane, over the pile of salt and filming what happens – the effect.

Speed bump research records what happens to a vehicle at a speed bump by measuring and photographing its position in three dimensions:

• Side to side in the traffic lane between the centre and shoulder lines,
• Along the lane with a large ruler, and,
• Vertically above the lane with another large ruler.

I did the same at my test site.  The painted traffic lines oriented the vehicle side to side in the lane.  A large ruler consisting of 1.0 foot graduations painted on the asphalt down the lane from the salt pile located the vehicle in that direction.  Another ruler consisting of 0.5 graduations marked on a sheet of plywood set at the side of the lane opposite the salt pile located the vehicle vertically.

I retained three professional photographers to film the position of the vehicle as I drove over the pile of salt.

• One was in the cab with me to film what I saw and experienced.
• Another was in the bucket of a boom truck down lane and 50 feet above filming the position of the vehicle side to side in the lane.
• The third was off to the side of the pile of salt filming the position of the vehicle against the backdrop of the rulers painted on the plywood and on the lane.

I also staged the position of the vehicle on the salt pile and had this filmed from a sea king helicopter for illustrative purposes – you would use a drone fitted with a camera to get these pictures today.  The photographer with his camera is shown above in my blog site masthead.

The RCMP told me that the vehicle was travelling at a speed of 50 km/hr or more when it hit the pile of salt.  This was based on tests by their accident reconstruction specialist.  I planned to do my test at that speed but start at the lower speed of 20 km/hr and gradually increase.

I drove the vehicle over the pile of salt at 20 km/hr as the cameras rolled.  It was pretty well all I could do to keep the vehicle in the lane after striking the pile of salt – it did veer off to the right a little and this was captured by the camera man in the boom truck.  Striking is an apt term.  And it was all the camera man in the cab with me could do to keep his camera steady as the vehicle rocked and rolled.

We saw on viewing film of the vehicle against the backdrop of the big rulers that the vehicle got 2.0 feet of air on striking the pile of salt and the front wheels stayed aloft for 18 feet before landing on the test lane again.

The three cameras recorded about 30 minutes of film.  I viewed this film and edited it to a four minute film clip to include in a preliminary report to the RCMP.  I reported that I could not continue the testing at higher speeds until I had safety and rescue procedures in place for the driver.

The RCMP and counsel on viewing the film clip and learning of my need for safety measures stopped all further testing.  “No need to continue testing, we have our answer”.

They quickly saw in the film clip the effect, the contribution of the pile of salt to the erratic behaviour of the vehicle and its airborne trajectory at 20 km/hr.  It didn’t take much imagination to know how the pile of salt would contribute to a fatal MVA at a speed of 50 km/hr.  Seeing is believing when you’re taking the measure of some things.  That’s often more than good enough for the justice system.

But all of this was also quantified by filming and recording the 2.0 foot and 18 foot airborne measurements and the veering of the vehicle off to the side of the traffic lane.

The forensic investigation of many failures and accidents needs input from more than one engineering, scientific or technical specialist.  These cases require the services of a principal investigator – a “generalist” forensic engineer.

The role of the generalist engineer is recognized by the American Society of Civil Engineers (ASCE) in their Guidelines for Forensic Engineering Practice. (Ref. 1)

The engineer retained by counsel serves as a principle investigator as soon as he recognizes his particular expertise must be supplemented by that of others. He identifies these specialties, coordinates their efforts, studies the findings of each, synthesizes and analyses all data, including that of his own specialty, draws conclusions and formulates an opinion as to cause.

This process is almost always the case with catastrophic failures.  But occurs often enough during investigation of the small to medium sized failures that characterize forensic engineering in Atlantic Canada. (Refs 2, 3)  And I suspect in Canada in general.

These smaller failures are seldom alike.  As a result, few engineers get to investigate hundreds of a particular type of failure or accident and specialize in it.  I seldom see the exact same failure a second time and must consult with other specialties often enough to supplement my expertise.  Or research the subtle differences between seemingly similar failures and accidents.

For example, slip and fall accidents – five that I’m familiar with are all slightly different, one in an odd way, and foundation failures, land slides, floods, fires, soil-steel bridge collapses, marginal wharf failures, old fuel oil spills, buckled bridge beams, defective step ladders, vibrating buildings, etc.  There are lots of specialists in different fields of practice, but not in all, and those that are available are not necessarily just down the street and around the corner.

In spite of the variation, we engineers are still retained to investigate the problems that occur and we do this quite well.  We are recognized as problem solvers and qualified to “figure things out” – including when we must supplement our particular expertise with that of others.

We function as principal engineers – “generalist” engineers, and also as specialists in our particular field.  We have the following key attributes of experts, including today a couple of important additional attributes:

Key attributes of experts:

• Education
• Training
• Experience
• Skill, and,
• Knowledge

Important additional attributes of experts serving as principal engineers:

• Principal investigator, “generalist” forensic engineering skills
• Report writing skills (most disputes are resolved out of court today based on an expert’s report)

You might be interested in four examples of forensic investigations that needed input from several specialties, all directed by a principal investigator, a “generalist” engineer:

Example #1

I investigated the cause of a soil-steel bridge failure that permanently disabled a car driver.  During that investigation I retained the services of:

• A land surveyor,
• A hydrologist,
• Two engineers experienced with corrugated steel structures – one in Ontario, the other in Massachusetts,
• A metallurgist, and,
• A metal detectorist (person who locates buried metal with a hand-held electronic device)

These specialists took part in the investigation in addition to my own specialties in civil and geotechnical engineering.  They contributed to formulating an opinion on the cause of the bridge failure.

I functioned quite well as the principal investigator in this case – the generalist forensic engineer.  However, if this had been a steel or concrete bridge I would have quickly referred counsel to a structural engineer experienced in bridge design as better qualified to be the principal investigator.  I could have contributed by investigating the adequacy of the bridge foundations.

Example #2

In another case, the RCMP asked if I could determine if a pile of soil-like material on a highway contributed to a fatal motor vehicle accident (MVA).  The vehicle drove over the material then off a 75 foot cliff and into the sea.

I wasn’t sure until I realized the pile of material was an earth structure – a structure in the built environment formed of earth.  Civil engineers specializing in geotechnical work are well qualified to investigate earth structures.

But, I wasn’t out of the woods.  I researched the literature on the investigation of fatal MVAs involving obstacles on a highway, and didn’t find a thing.

But I did catch onto the fact that the pile of soil-like material on the highway was like a speed bump, and there was an extensive literature on speed bump research and design.  So, I investigated the effect of the material on the vehicle like it was a speed bump.  The investigation involved full scale field tests on an airport runway and a lot of photography.

The specialists assisting me as the principal investigator were:

• A helicopter pilot
• Three professional photographers
• A film editor
• Accident reconstructionist (the RCMP provided data gathered by their specialist on how the accident occurred)
• Boom truck operator
• Contractors to build the earth structure and paint traffic lanes on a runway

Example #3

The continuing and excessive foundation settlement of an industrial building 10 years after it was constructed – ongoing 10 mm settlement per year, is another good example of a principal engineer directing a forensic investigation.  Also, in this case, designing a method to stop the settlement.

It was an easy investigation of cause – I determined the foundation soil conditions and saw immediately that they were inadequate.  Fortunately, the soil conditions were also perfect for grouting as a way of strengthening the soils and stopping the settlement.

The investigation involved the following specialties including my own in civil and geotechnical engineering:

• Geotechnical engineer
• Structural engineer
• Land surveyor
• Grouting engineers
• Borehole drillers
• Peer review engineer

Example #4

A final example is the Edmonton bridge failure that occurred last March, 2015  This was a serious structural engineering failure.  I would not qualify to direct such an investigation but would qualify to contribute input on the adequacy of the foundation soils supporting the bridge.  Also, as a civil engineer, I can look at the elements in the failure and suggest possible causes, as I did last year.

I can easily imagine a principal investigator, a “generalist“ engineer, retaining the services of the following specialists during investigation of the failure:

• A micro-meteorologist (to assess the weather and winds at the bridge site at the time of the failure)
• A bridge design engineer
• A structural engineer
• A bridge construction engineer
• Off-site steel beam/girder fabricator
• Crane operator
• Foundation engineer
• Geotechnical engineer

References

1. American Society of Civil Engineers (ASCE), Guidelines for Forensic Engineering Practice, 2nd ed, 2012, page 9.  (ASCE has represented civil engineers in North America since the mid 1800s)
2. Forensic engineering practice in Eastern Canada.  Published May 7, 2015
3. What do forensic engineers investigate in Atlantic Canada?  Published October 9, 2014

That is, thorough forensic investigations and reliable, objective expert reports.

Civil procedure rules governing expert’s reports are strict. (Ref. 1, 2)  You can’t have a good report without a thorough investigation.  Peer reviewing an expert’s report ensures a thorough investigation.

Peer review is needed but isn’t being provided.  I’ve read four poorly written expert reports in recent years based on inadequate investigation and reasoning.  Really, very little investigation in most cases and no reasoning in all cases.  I’m sure there are others out there.

Peer review is needed in forensic engineering every bit as much as in scientific research.  Research papers are published in reputable journals only after they are peer reviewed.

Peer review is provided for in the remediation of petroleum contaminated sites.  The provincial governments in Atlantic Canada reserve the right to peer review a report on the remediation of a contaminated site according to the Atlantic risk based corrective action process (RBCA). (Ref. 3)

There’s no question the standard of care for expert reports must be as high as that for research papers and reports on remediated sites.

I published an item on peer review in the past (Ref. 4) but was reminded of it when I was reviewing a recent handbook on expert work. (Ref. 5)  Also when I was reviewing the RBCA process recently.  Peer review is referenced 38 times in the index of the 626 page handbook.  The authors discuss peer review on dozens of pages.  Their guidance in this text – and previous handbooks on report writing (Ref. 6, 7), is based on review of 100s of civil cases.

***

In science, peer review is the process by which an author’s work is checked by a group of experts in the same field – his peers, people of similar qualifications, experience, and competence.  They make sure it meets the necessary standards before it is accepted and published. (Ref. 8)  It constitutes a form of self-regulation by qualified members of a profession within the relevant field (Ref. 9).

Put another way (Ref. 10), peer review is specifically geared to (my parenthetic additions):

• Catch any potential biases of the primary examiner (the forensic engineer),
• Promote the examiner’s heightened diligence (promote thorough forensic investigation)
• Pursue each important clue (follow the evidence), and,
• Recognize the clinical significance as it surfaces (objectively recognize and accept the findings).

Peer review has been practised a long time in science and is essential to obtaining good science.  Forensic engineering must receive the same rigid peer review before going to the justice system to further ensure the system gets what it needs.

***

It would be easy to include a simple form of the peer review process in the investigation of a failure or accident in the built environment.  As easy as Counsel getting an independent consulting professional engineer to review the investigation and report of the investigating engineer.  To check that the investigation was carried out to the standard of care existing at the time and that the report meets the requirements of rules governing expert reports.  From that simple start, gradually move to a more comprehensive process over time.

Professional engineering societies have similar guidelines for those practicing in the forensic geotechnical, foundation, and structural engineering fields (Ref. 11 to 14).

***

The adoption of the peer review process will be driven in part by the increased emphasis on preparation of a report for the justice system – and less emphasis on discovery and trial, as a result of civil procedure rules such as Rule 55 in Nova Scotia.

The rule spells out the requirements of the expert.  They are exacting in requiring that the expert is thorough, reliable, and objective, and reports his evidence and reasoning, and also states what other conclusions might have been drawn from his evidence. (Ref. 1, 2)

***

Better that Counsel arrange to have his expert`s report and investigation peer reviewed and catch any deficiencies that might be present, than an expert for an opposing party do this.

References

1. Counsel, tell your expert about the Rule governing expert opinion. It’s important. Published September 11, 2015 at www.ericjorden.com/blog
2. Nova Scotia Civil Procedure Rule 55, sub-section 55.04
3. Atlantic Risk Based Corrective Action process (RBCA), 2015
4. Peer review in forensic engineering and civil litigation.  Published November 26, 2013
5. Mangraviti, Jr., James J., Babitsky, Steven, and Donovan, Nadine Nasser, How to Be a Successful Expert Witness: SEAK’s A-Z Guide to Expert Witnessing, SEAK, Inc, Falmouth, MA 2015
6. Mangraviti, Jr., James J., Babitsky, Steven, and Donovan, Nadine Nasser, How to Write an Expert Witness Report, SEAK, Inc, Falmouth, MA 2014
7. Babitsky, Steven and Mangraviti, Jr., James J., Writing and Defending Your Expert Report: The Step-by-Step Guide with Models, SEAK, Inc., Falmouth, MA 2002
8. Merriam-Webster Dictionary, 2016
9. Wikipedia, Google
10. The Forensic Panel, Google
11. Lewis, Gary L. ed., Guidelines for Forensic Engineering Practice, ASCE, the Association of Civil Engineers, Virginia, 2003
12. ASCE, Guidelines for Failure Investigation, Virginia, 1989
13. Ratay, Robert T., Forensic Structural Engineering Handbook, McGraw Hill, New York, 2000
14. ASFE, Association of Soil and Foundation Engineers, A Guide to Forensic Engineering and Service as an Expert Witness, 1985
15. Merriam-Webster Dictionary, 2013
16. Wikipedia, Google

There’s an argument for the justice system to go on site and see what it’s really like for the expert.  See what he’s got to deal with, and describe and explain to them later.  That means judges, juries, and counsel for all parties, also insurance claims managers.  It’s messy out there and not at all clean, tidy and precise as might be gathered from the text books.

I’ve seen the justice system on site less than half a dozen times in the years I’ve been investigating engineering failures and accidents.

I thought of this recently when I was examining and measuring conditions on a construction site.  I was knee deep in messy, wet pits in the ground and cramped in tiny, grubby crawl spaces.  And it was raining off and on too.  I was happy though, I was collecting valuable data.

But how to tell the justice system later that conditions were different from what I expected and more difficult and expensive to quantify?  In this case, less accurate for one element of the problem but more informative for a second.

How to describe this in words?  I got pictures and this will help.  But, seeing is believing.  It’s easier if the justice system has seen the conditions.  It’s easier then for the expert to explain the technical issues arising from the conditions associated with the failure or accident.  Most of our knowledge is acquired visually – about 80 to 85 percent, so come out and see and understand better what the expert is saying.

Bibliography

1. An expert’s “dirty hands and muddy boots”.  Posted December 20, 2013
2. The messiness of some forensic engineering and insurance investigations is illustrated by messy snow banks.   Posted April 14, 2015
3. More about messy, lumpy Mother Nature and how we deal with her effect on our forensic engineering and insurance investigations.  Posted April 23, 2015

This is particularly the case when counsel is assessing the merits of a case.  There’s a strong argument for consulting an “expensive” expert then.

This is echoed in the remarks of no less an authority than John Sopinka, former judge, Supreme Court of Canada (Refs 1 and 2) and in the text by the quite respected David Stockwood, Q.C., Ontario. (Ref. 3)

A key technical issue missed by counsel could render a case untenable.  Or be too expensive to investigate relative to damages thought due the Party and to the worth of the file to counsel.  Best to spend some money on an expert at the case-assessment stage than possibly lose a lot of money later.

I blogged last year on the importance of retaining an expert “…early in the life of a case”. (Ref. 2)  I was reminded of its importance to a Party seeking justice and the money involved on reading the following in an engineering case study:

“As a wise man once said about “expensive” experts, “When you have to hire one to undo the work of an amateur, they don’t seem so expensive after all.” ” (Ref. 4).

The case study was of inadequate renovation of a building that cost the owner $300,000 a few years ago. (Ref. 4)  The expert’s fees are certain to have paled by comparison.  I also recently investigated an inadequate renovation that is likely to cost a lot of money to fix.

Counsel almost always recognizes that the cause of a failure or accident must be determined – a key technical issue for sure.  But there are often other issues – key ones and subordinate ones – that are beyond counsel’s technical expertise to identify.  Some of these might need to be investigated in determining cause, at unexpected expense.

I’ve had the occasional investigation stopped because of mounting cost to the worth of the file.  Counsel’s costs are cut but I wonder to what extent justice for the Party is compromised by an incomplete forensic investigation?

The cases likely will be argued still but without benefit of complete technical input.  One case is certain to be argued and likely cost the law firm much more compared to the cost of an “expensive” expert.  In this case, for want of a simple, one line, 2″ long, high school, arithmetic calculation that would quickly resolve an important technical issue in counsel’s favour.  Without the calculation three parties will keep arguing their respective subjective assessment of the size of a feature in the landscape – on and on and dollar after dollar.  I offered to report verbally but senior management declined.

What happened in these cases was that non-technical people – counsel, with all due respect, estimated the cost of technical services unrealistically low when the merit of the cases were being assessed.  Yet in these cases – three come to mind, the awards would be well into six figures.

Consulting with an “expensive” expert before a case is taken will ensure most if not all technical issues are identified.  And the need recognized to investigate these at some cost if the case has merit.  The expert might cost in the very low 1,000s, the possible need for forensic investigation in the low 10,000s won’t be a surprise, and awards in the 100,000s won’t be compromised by investigations stopped in mid-task.

Reference

1. Sopinka, John, Judge, Supreme Court of Canada, The Use of Experts, Chap 1, The Expert: A Practitioner’s Guide, Volume 1 by Matthews, Kenneth M., Pink, Joel E., Tupper, Allison D., and Wells, Alvin E. Carswell 1995
2. Please, Counsel, retain an expert “early in the life of the case”.  Posted March 27, 2014
3. Stockwood, Q.C., David, Civil Litigation, A Practical Handbook, 5th ed, 2004, Thompson Carswell
4. Reference Advocates Principles
5. Nicastro, David H., editor, Failure Mechanisms in Building Construction.  ASCE Press, 1997 page 26

Bibliography

1. The role of a professional engineer in counsel’s decision to take a case – Update Posted May 21, 2014
2. A bundle of blogs: A civil litigation resource list on how to use forensic engineering experts, Posted November 20, 2013
3. Lewis, Gary L., editor, Guidelines for Forensic Engineering Practice, American Society of Civil Engineers (ASCE), 2003

Going slow – like many months for a simple investigation, longer still for complex ones, ensures the cause of the problem is determined.  And the investigator doesn’t succumb to the tyranny of the obvious – as I almost did. (Ref. 1)  You’ve got to have time to think and reflect.  Going slow also helps the owner adjust to seeing his property taken apart during the work.

I investigated the cause of two wet basements in the past 1.5 years.  More than just wet, a flood in one case, 3 inches deep, and very wet in the other.

There was also water in depressions on the properties that sloped down to nearby lakes.  That meant poor surface drainage and probably high water tables – evidence of a possible cause of the wet basements..

The homeowners helped in both cases.  One used a novel method for determining the correct cause of her wet basement.  I’ll use her simple technique in future.  The other was in the right place at the right time to see the actual cause of their wet basement, and in a very striking way.

Both Houses

Both basements were finished including the floors.  But you could see water flowing from under the finished floors and across the exposed concrete floor in adjacent furnace rooms.  The water came from the direction of the basement walls on the up-slope side of the properties.

We cut small holes in the gyproc at the bottom of the walls and gradually added other holes and enlarged them – in a sense, we chased the wet basement problem.  This exposed the wood sill at the bottom of the walls and the area where the concrete floor abuts the concrete wall.  We also took up part of the finished floor in one house.

The owners helped and we went slowly so they could get their heads around the dismantling and the mess.  These were well-appointed, $350,000 plus homes, one about 30 years old and the other 40.

The exposed wood sills were water stained at both properties.  The stain gradually faded along the length of the wood sills from a dark area in the middle.  The stain indicated the wall was leaking, and the dark area suggested the location of the leak.

Just to be sure, we cut small holes in another wall in each house well away from where the water was seen in the houses.  We saw clean, unstained wood sill indicating no leaks.  There was a leak along one of these adjacent walls 20 years earlier that was fixed by constructing a new, perimeter footing drain.  Fine soil clogs these drains often enough after a few decades.

I concluded a clogged footing drain was the cause of the flooding at both houses, a good initial hypothesis as to cause.  But, I was in for a surprise.

(You can imagine there was quite a mess in both houses now with dismantled wall debris everywhere.  But we were going slowly – weeks now, and soon months)

Where was the leak?  How was water getting from a clogged footing drain into the basement – if that was the source?  The concrete wall was stained a little at the location of a hairline crack in one house.  But this crack was so fine I quickly dismissed it as the source of the leak, and it was above the suspect footing drain.  Surely such a tiny crack was not the cause.  Surely.

Where was the leak then?  I thought about the construction joint where the concrete floor abuts the concrete basement wall in both houses.  It measured 1 to 1.5 mm wide and ran the length of the walls.  The construction joint was also down near the suspect footing drains on the outside of the basement wall.

I concluded that the footing drain at both homes was clogged after 30 and 40 years, water was backing up in the drains and getting into the basement through the construction joints.  We would dig up the footing drains at both houses and fix them.

It took me a while to conclude that construction joints could admit so much water.  The penny dropped, so I thought, when I realized that not much water would flow through a 1.5 mm hole but a lot would flow through 100s of 1.5 mm holes joined together.  Like a line of holes in a sieve or the holes in a garden hose used for irrigation.

House #1

But, again, just to be sure, we uncovered a greater height of wall in House #1 – more time more debris, and saw that an area of the wall was honeycombed a few feet above the wood sill.  There were small holes in the wall between the pieces of gravel in the concrete.  The inside wall was porous.  This happens when the concrete is not well mixed during construction.  It doesn’t usually cause a problem because it’s localized and above the footing drain.

Fortunately, we had a very heavy rain a few hours after work.  My client called to say water was flowing from the honeycombed area like water from a tap.  It stopped shortly after the rain stopped.  He videotaped and I saw that it was so.  My client was in the right place at the right time.

We uncovered more wall later and found that a large area was honeycombed.  We also uncovered the outside of the wall and saw that the honeycombing – the porous area, continued through the wall.  We also saw that the water table was at the level of the honeycombing.

There was a source of water and a means for the water to get through the wall, through the porous honeycombing.  The honeycombing and the high water table were the cause of the wet basement in this house, not the footing drain.

We fixed the leak by patching the outside of the wall well above the footing drain that we had considered digging up, and at much lower cost.

(The patching details are not so important to my message here about the advantages of a “slow”, thorough engineering investigation)

House #2

Also, again to be sure, my other client, House #2, decided to investigate the innocent-looking, fine crack in their wall when I was away.  She simply took a garden hose and let it run for some time at different locations against the wall starting at the fine crack.

She saw that water flowed through the crack and stopped when she removed the hose.  She also saw that less water flowed when the hose was at increasing distances from the fine crack.  The fine crack and a water filled depression in the sloping ground were the cause of the wet basement, not the footing drain. 

We fixed it too by patching the outside of the wall at the location of the crack, also at a much lower cost than digging up the footing drain.  We did expose the top of the footing drain over a short distance during the patching.  It appeared to be well constructed.

(We are going to monitor the effectiveness of this repair over the next couple of years)

***

So, four or five months later in both cases after a “slow”, thorough investigation – and a lot of gradually accepted mess, we determined the correct cause of the wet basements.  And we fixed them for a lower cost than might have been the case if I had remained in the grip of the obvious.

References

1. “Getting seduced by the tyranny of the obvious”  Posted December 9, 2013 at www.ericjorden.com/blog

You might be interested in an article by a U.S. civil litigation lawyer on the use of aerial photographs in environmental litigation – see Appendix.  I came across it while researching material for a forensic engineering investigation that I was carrying out.

References at the end of the article in the Appendix might be of interest to civil litigation lawyers in eastern Canada.

The article is quite descriptive and detailed.  It possibly claims a bit more potential for these types of high altitude aerial photographs taken from 1,000s of feet than is actually the case, but the claim is close to reality.

For certain, all the claims for high level aerial photographs do apply to the low level aerial photographs taken with drones at 10s to 100s of feet that I noted recently. (Refs 1 to 4)  I’ve used both high and low level aerial photographs in my civil, geotechnical and forensic engineering work for years.

Following are a few non-technical comments on aerial photographs to help you know if the method is applicable to your case:

High level aerial photography

This type of high altitude aerial photography is readily available everywhere in north America.

The ground is photographed from aircraft flying at altitudes of several 1,000s of feet.  You get photographs of quite extensive areas – 1,000s of feet across.  However, you can sometimes identify quite small objects as mentioned in the article in the Appendix.  You can also view a site in 3D with overlapping pairs of photographs.

The civil engineer/former land surveyor in me does not usually go on the site of an engineering failure or problem without first getting this type of photography.  I got it most recently for a site in Cape Breton, N.S.

The high altitude photography has particular application to tracking changing conditions on the ground over time or the conditions at a site at some point in the past.  Like the activity on a site as noted in the article.

On one occasion, I relied on high level photography during the forensic investigation of the inadequate underpinning of a structure – to confirm what was not there.

Lidar

Lidar (Light, Radar), another form of high level remote sensing from an aeroplane, is not so readily available but invaluable when it is.  It measures distance by illuminating a target – e.g., a point on the ground, with a laser and analysing the reflected light.  Radar measures the location of the point.  A gazillion points are illuminated and measured and a contoured topographic map produced.

It was very valuable during my investigation of a failure in Sydney.  The site had flooded, a building had settled and the foundations cracked, and a swimming pool had settled a lot – catastrophically.  Lidar imagery clearly showed the probable cause of the flooding and settlement – from an altitude of several 1,000s of feet.  This was one of the most satisfying experiences I’ve had using remote sensing technology to investigate the cause of a failure.

Low level photography with drones

This type of low altitude photography is readily available in eastern Canada and at reasonable cost.  The drones consist of rotorcraft – mini helicopters, and small, fixed wing aircraft fitted with a camera.  The craft are a few feet in size.  They are flown remotely by a pilot on the ground.  The investigating engineer directs the pilot on the photographs and video to take.  That is, the altitude above the site, the distance from the site and the angle with respect to the horizon, also whether still or video.

Photographs taken from drones flying at metres to 10s of metres are able to record existing conditions in considerable detail – almost minute, at the time of the flight.  It is easy to see an object six inches across – even a toonie, in such photographs.  Low level photography produces images of very compact sites – 10s to 100s of metres across.

It can also be used today to start building a photographic record of changing site conditions for study and analysis in the future.

Low level aerial photographs taken from drones would have been quite useful in the forensic investigation of the bridge that failed while under construction in Edmonton earlier this year. (Refs 5 and 6)

Before drones fitted with cameras were available, I occasionally hired small planes to fly over a site and take photographs at quite low levels – several 100s of metres.  I occasionally went aloft in the plane myself.

This technique was quite valuable to me in solving problems with a sewage lagoon in the Annapolis Valley in Nova Scotia one time.  From above, you could easily see the line of seepage where the lagoon was leaking.

In both low and high altitude photography, and the study, analysis, and interpretation of the images of what’s on the ground – known as ‘terrain analysis’ – ground proofing is essential. (Ref. 7) This involves going on the site and checking at selected locations that what you thought you saw in the photographs is actually on the ground.

***

There’s a lot of sophisticated aerial photographic techniques being used in forensic investigation today.  I’m using them in eastern Canada, and they are getting good use in the U.S. as indicated in the article in the Appendix.

But, at the end of the day, an expert has to get on site and “get his hands dirty and mud on his boots” examining the site in detail – something more than the ground proofing noted above. (Ref. 8)

References

1. A picture is worth a 1,000 words, possibly many 1,000s in forensic engineering with a new aerial photographic technique.  Posted January 15, 2014
2. New forensic aerial photographic method proving extremely valuable.  Posted  January 30, 2015
3. Forensic photography – the expertise available in eastern Canada.  Posted February 26, 2015
4. Fixed wing drones – another tool in forensic engineering investigation.  Posted November 4, 2015
5. Globe and Mail page A8 Tuesday March 17, 2015, “Buckled girders may delay Edmonton bridge a year”
6. Wind, construction crane and inadequate cross-bracing caused Edmonton bridge failure: An initial hypothesis.  Posted March 27, 2015
7. Way, Douglas S., Terrain Analysis: A guide to site selection using aerial photographic interpretation, 2nd edition, 1978, McGraw Hill, New York
8. An expert’s “dirty hands and muddy boots”.  Posted December 20, 2013

Appendix

Using Aerial Photography to Win Environmental Cases by Kim K. Burke

June 7, 2011

Most environmental lawyers and consultants are first introduced to aerial photographs when reviewing Phase I Environmental Site Assessments (ESA) prepared in accordance with ASTM E-1527-05.  However, the use of aerial imagery in Phase I ESA reports to determine historical site conditions barely scratches the surface of the effective use of aerial photography.

Aerial photography, also referred to as aerial imagery (as a component of remote sensing), is a potent tool for environmental trial lawyers.  Databases of aerial photographs from 1938 are readily available through aerial photography clearinghouses.

The photos are usually taken with a high resolution camera using overlapping images.  The overlapping images are called “stereo pairs” and when viewed as “diapositives” through a stereoscope on a light table produce a three dimensional image of the surface features: buildings, drainage patterns, ravines, containers, tanks, vehicles, mounds, etc.  Vertical and horizontal surface features can be measured, depending on the quality of the photographs.

Aerial photography interpretation can be used in conjunction with geographic information systems (GIS) to develop trial exhibits recreating site conditions at the time of important historic environmental events.

Accurate aerial photography interpretation is a critical component of environmental forensics.  The stereo pairs should be interpreted by a seasoned imagery analyst trained in environmental remote sensing.  Many analysts are former employees of the military or the U.S. government.

Finding a qualified environmental imagery analyst is difficult, because the telltale signs or marks on the aerial photographs of ground level activity, referred to as “signatures,” are different for 55 gallon drums or former burial pits than, for example, intermediate range ballistic missiles.

Stereo pairs are usually shot by aircraft when cloud and vegetative cover are at a minimum (excepting aerial imagery by agencies analyzing crop growth).

Some aerial photos are taken using cameras that detect ranges of the electromagnetic spectrum not visible to the human eye, such as infrared signatures.

The detail can be stunning: some aerial images permit identification of features as small as six inches, and in some cases permit license numbers to be read on vehicles when taken from low-altitude oblique angles.

Collecting and analyzing the historical library of aerial imagery is not a task for most environmental consultants.  Specialists can call upon not only the more widely used public sources of aerial photographs, but also upon databases of lesser-known aerial photography companies that operate on a regional basis.

Because of the incredible detail and information that can be extracted from stereo positives viewed through a stereoscope on a light table (a table that projects diffuse light from underneath the positive images into the stereoscope), it is usually a mistake to order “prints” from the public resources offering to sell historical aerial photos.

To say that aerial photography can be a game changer in environmental cases is an understatement: in one case handled by this firm, the historical aerial photographs showed trucks tipped to dump waste into a ravine…a fact denied by the prior owner of the real property.¹   The case settled shortly after sharing these photos with the responsible party.

Juries are intrigued and persuaded by visual and scientific evidence…sometimes known as the “CSI effect.”²   This law firm has used the testimony of experts interpreting environmental signatures on historic aerial photographs.³   The impact on jurors (and judges)⁴ can be profound.

Environmental attorneys and consultants not trained in aerial photography signature interpretation can miss important clues about past uses of the property.⁵

The photographs can also be used during, or after, witness interviews to test the accuracy of a person’s memory.

Of course, aerial photographs provide an excellent means of impeaching the credibility of opposing witnesses who testify with professed certainty about different historic site features.

For more information about the effective use of aerial photographs in environmental cases, please contact Kim Burke or any member of the Taft Environmental Practice Group.

References

¹Burke, Kim K., The Use of Experts in Environmental Litigation: A Practitioner’s Guide, 25 N.Ky.Law Rev. 111 (1997).

²Lawson, Tamara F., Before The Verdict and Beyond the Verdict: The CSI Infection Within Modern Criminal Jury Trials, 41 Loy.U.Chi.L.J. 119 (Fall 2009).

³Stout, Kristen K. and Hickerson, Glen H., Environmental Research, Inc., The Use of Aerial Photography to Determine Contamination Events at Agricultural Chemical Facilities, Proceedings before the American Academy of Forensic Sciences, Colorado Springs, CO (Feb. 2003).

⁴Nutrasweet Company v. X-L Engineering Company, 227 F.3d 776, 788 (7^th Cir. 2000)(expert testimony interpreting aerial photographs admissible to show history of site contamination).

⁵Burke, Kim K., 1999 Annual Meeting, American Academy of Forensic Sciences: Experts and Attorneys in Environmental Litigation: Avoiding Common Mistakes, Coronado Springs Resort, Orlando, FL.

Expect the unexpected.  This is relevant when designing foundations to support a structure.  Also, when investigating the cause of a failure in the built environment – a forensic engineering investigation.

I sometimes wonder how often the designer does this – takes the ground for granted, and gets away with it because the foundation soils in Nova Scotia are often very strong.  That includes well constructed, man-made filled ground.

I thought of this when an experienced structural engineering friend of mine exclaimed recently, “There’s sand everywhere in Moscow..!!”.  He was describing his trip to the Scandinavian countries and Russia this summer.  He went on to describe the size of the grains, the expanse of the deposit and the level terrain.  It was like he was seeing a natural, undisturbed deposit of sand for the first time.

That might be understandable.  My friend has practised structural engineering in Nova Scotia since the 1970s.  Much of the province is covered by dense mixtures of gravel, sand, silt and clay – natural, undisturbed glacial soils.  This is what my friend probably expects to find beneath a site when he’s designing the foundations, and the steel, concrete or timber supporting the structure above.

(Everything in the built environment can be thought to have three major components:

• the Structure above the ground surface,
• the Foundations at or near the ground surface, and,
• the Foundation Soils below.

The lower you go the less glamour there is, and too often the less attention paid to what’s below.  “There’s no glamour in the ground”. Ref. 1)

Such an expectation by my friend would be dangerous.  The comfort we feel in Nova Scotia about what is below the ground surface can get you in trouble.  It’s better to “expect the unexpected” as I learned practising geotechnical engineering – a civil engineering specialty, in the U.K., Australia and eastern Canada.

We have loose sand and silt in Nova Scotia and also soft clay – poor foundation soils.  Not a lot but it’s out there.  We also have poorly constructed fills – “un-natural, disturbed“ mixtures of different materials.  Fill is material brought from elsewhere and placed on the ground to raise the level.

Poorly constructed fill can cause problems for low-rise structures like one and two story buildings.  In fact, when I investigate the cause of a foundation failure, as an initial hypothesis, I “expect” to find a poorly constructed fill beneath the foundations.  Or one of the other poor foundation soils that occasionally show up on our construction sites.  This expectation is reasonable because I would have evidence suggesting something is wrong down below when most of the time in Nova Scotia all’s good there.

Appendix

Good fill in engineering usually consists of well compacted mixtures of soil – gravel, sand, silt and clay, placed on undisturbed, natural soil.

Poor fill can consist of these materials plus varying amounts of topsoil, peat, roots, boulders and/or debris.

Geotechnical engineering is a civil engineering specialty that identifies the types of soils and rocks below the ground surface –  below proposed foundations, measures and tests their physical properties, and analyses and calculates how they will perform when used as engineering materials by design engineers.

Reference

1. A quite well known comment by Karl Terzaghi, considered the father of soil mechanics, the science underlying geotechnical engineering.