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.

Make sure your expert knows about this Rule before he starts his investigation. Particularly the sub-section on the content of an expert’s report. (Ref. 1)  Abiding by the Rule, as required by the judicial system, may increase the time spent gathering data – the forensic engineering investigation, and also the time spent analysing the data and writing the report.  Increased time means increased cost.

This is possible – higher costs, for the small to medium size forensic investigations typical in Atlantic Canada and I suspect across the country.  Certainly when these investigations are complex.

Experts are unlikely familiar with the Rules in the same way that lawyers are unlikely familiar with the expert’s field of practice.

Engineers sometimes investigate a failure or an accident and report the cause but stop short of a detailed description of what they did.  Particularly the technical analysing and reasoning lest counsel’s eyes glaze over.  Many lawyers just want an answer – “and spare me the details”.  This might be the case when the engineer is retained as a consulting expert rather than a testifying expert.

Knowing about the Rule and that it requires more comprehensive reporting doesn’t mean estimating the cost of the forensic investigation is any easier. (Ref. 2)  It just alerts counsel and the expert to the information that must be reported and that costs may be higher.

1. Things leading to the opinion

The expert’s report, according to the Rule, must include everything the expert regards as relevant to the expressed opinion.  This approximates a full engineering report.

Everything means that the report contains all of the following information to support the opinion (I have expanded and added to the statements in the Rule according to how engineers investigate failures and accidents):

1. Identify and describe in detail the steps and tasks carried out during the investigation and the purpose of each.
2. Describe any research carried out.
3. List and describe the data obtained from each task.
4. Analyse the data from each task and any research – its nature, what it means, how the data from the different tasks are related to each other, and how each is related to the failure or the accident.
5. Fully explain the reasoning leading to the opinion.
6. Describe a test(s) to formulate or confirm the opinion.
7. State the degree of certainty with which the opinion is held.
8. State any qualification put on the opinion because of the need for further investigation or for any other reason.
9. Reference all the literature and other material consulted in arriving at the opinion.
10. List the documents and other information acquired to prepare the opinion.

This is comprehensive reporting.  It takes time and it can be expensive particularly in a complex case.

2. Things leading to a different opinion

But the Rule also requires that the expert’s report draw attention to anything that could reasonably lead to a different conclusion.  If “drawing attention” to “anything” means identifying and investigating other interpretations of the data, or follow-up investigations, then including the listed information on these things takes time.  It may not mean exhaustive investigating and reporting but even a little more adds to the cost of an expert’s opinion..

Experts may not expect such comprehensive report requirements. It’s important to give an expert a heads-up at the time he is being retained and before he starts his investigation.  I was given a copy of this rule by counsel shortly after it was published – after I had carried out a forensic engineering investigation but before I had written my report.  It turned out okay but we like to know about such requirements before we start an investigation.

References

1. Nova Scotia Civil Procedure Rule 55, sub-section 55.04
2. A bundle of blogs: A civil litigation resource list on how to use forensic engineering experts.  Posted November 20, 2013 (Contains blogs on estimating the cost of forensic investigations)