Update: Where does an expert’s initial hypothesis come from?

I commented last month on the basis for an expert’s hypothesis during the merit assessment stage and gave a few examples. (Ref. 1) You may remember that the hypothesis or initial oral report comes from:

  1. Your briefing
  2. The expert’s experience
  3. Published data on causes

The examples of published data were quite informative. (Refs 2, 3, 4) The most detailed was about the 209 ways a building can fail – useful information and readily available to the expert when assessing cause. (Ref. 2)

There’s more.  A building is only one type of structure in the built environment.  There are actually about 18 different types as listed below. (after Ref. 4)  Each structure can fail in several different ways.  The causes have been researched and published for most of the 18 like the 209 causes for a building.

(It was Ref. 4 that prompted this blog update – it extends our understanding of failure and accidents to all types of structure)

Your urban environment where you live contains some or all of the following types of structure:

  1. Bridges
  2. Dams
  3. Tunnels
  4. Highways
  5. Embankments
  6. Excavations
  7. Natural, and man-made fill slopes
  8. Multi-story buildings
  9. Industrial buildings
  10. Residential buildings
  11. Foundations
  12. Basements
  13. Retaining walls
  14. Infra structures
  15. Tanks
  16. Storage bins
  17. Chimneys and stacks
  18. Towers; both guyed and free standing

The causes of failure of these structures are categorized according to the:

  • Structure - those listed above and again in the Appendix
  • Main Component in the structure – beam and slab, an arch, long span roof, etc
  • The component’s Material - steel, concrete, wood, masonry, etc.

The categorization is more detailed and technical than this but the above gives you an idea..

(The Appendix lists the different structures, their components and component materials)

The researchers identified the several different ways each Structure can fail.  For example, What causes bridges to fall down?  Towers to topple?  Multistory buildings to settle?

They then looked closer at the main Component(s) in each structure and identified the different ways these failed.  For example, What are the different causes of cracks in concrete floor slabs?  Why do roofs collapse?

Finally, they looked closer still at the different Materials used in the components of structures and how they failed.  Why does steel break?  It certainly does at times.  What causes concrete-wood connections to come apart?

The result is a wealth of published information for the expert to consider when forming a hypothesis – 100s of different ways a structure, it’s components, and the component’s materials can fail in the built environment.  All researched and published and available to guide the expert as you brief him during the merit assessment stage.

He’s thinking Structure, Component, Material as you talk and forming an initial hypothesis, or, more correctly, an initial oral report to guide you on whether to take the case or in assessing the claim.  It might be a rough report but it’s well founded on a lot of published data – and better than not talking to an expert.

(It occurs to me this late hour that similar data could be compiled and published on the causes of personal injury accidents like slip, trip and fall accidents)


  1. Where does an expert’s initial hypothesis come from?  Posted February 25, 2019
  2. Nicastro, David H., ed., Failure Mechanisms in Building Construction, ASCE Press, American Society of Civil Engineers, Reston, Virginia 1997 (Readily available by interlibrary loan from Memorial University, Newfoundland)
  3. How many ways can a building fail, and possibly result in civil litigation or an insurance claim? Posted July 10, 2014
  4. Janney, Jack R., Guide to Investigation of Structural Failures, ASCE (American Society of Civil Engineers) 1979, 1986


(The following lists are after Ref. 4 with some additions based on what I’ve seen over the years)

Structure: Causes of failure have been researched and identified according to the following types of structure:

  1. Bridges
  2. Dams
  3. Tunnels
  4. Highways
  5. Embankments
  6. Excavations
  7. Natural, and man-made fill slopes
  8. Multi-story buildings
  9. Industrial buildings
  10. Residential buildings
  11. Foundations
  12. Basements
  13. Retaining walls
  14. Infra structures
  15. Tanks
  16. Storage bins
  17. Chimneys and stacks
  18. Towers; both guyed and free standing

Component: Causes of failure have been researched and identified according to the main types of components in the different structures

  1. Arches, rigid frames and trusses
  2. Suspension structures
  3. Long-span roofs
  4. Beam/Slab combinations
  5. Flat plate and flat slab
  6. Multistory rigid frames
  7. Thin shells and membranes
  8. Cantilevers

Material: Causes of failure have been researched and identified according to the materials used to make the different components in the structures, and the connections between the materials

  1. Steel
  2. Concrete
  3. Masonry (structural clay and concrete block)
  4. Wood
  5. Plastic
  6. Failure causes classified by connection type
  7. Steel to steel connections
  8. Steel to concrete composite connections
  9. Monolithic concrete member intersections
  10. Precast concrete to precast concrete connections
  11. Pre-stressed concrete
  12. Masonry connectors
  13. Timber fasteners and adhesives
  14. Expansion type connections

Where does an expert’s initial hypothesis come from?

When you rely on an expert’s initial hypothesis during the merit assessment stage you rely on a well-founded hypothesis.  In fact, it’s more than a hypothesis – a guess – it’s an initial oral report based on the evidence. (Refs 1 and 2)

The evidence is

  • Your briefing on the claim, accident, failure, dispute
  • The expert’s experience
  • Published data on the causes of failures and accidents in the built and natural environments

You telephoning and briefing an expert on a situation triggers his thoughts of past experiences and also modes of failure as published in the literature for different structures.  He’ll tell you, orally, what he thinks about cause, and it’ll be more than just a guess.

Tell me the issue is foundation subsidence on filled ground and I’ll tell you it’s likely inadequate materials testing and inspection during construction (experience) or inadequate geotechnical investigation (experience plus published research).

Brief me about a slip and fall accident on a wet floor in a dry sauna and I’ll tell you where the water came from (experience).

Tell me a site is still contaminated after an environmental assessment and remediation and I’ll identify three possible causes, one more likely than the other two (experience) .

Other experts in different branches of engineering and applied science can do the same.

There’s some interesting and helpful information in the following on where initial oral reports come from.

1. Your briefing You’ll describe the situation to the expert and report what you know about the claim, dispute, failure or personal injury.  This based on what you have learned from the parties involved, or your understanding if you are one of the parties or represent one.  Your briefing would include the technical issues as you might understand and perceive them.  Also what you believe must be investigated.

The expert will ask questions based on what he’s hearing.  He’ll ensure the Who? What? Where? When? Why? and How? of the situation are answered.  He’ll note technical issues that he might see at this early stage and comment on yours. The expert will sift through your briefing for hard and soft evidence.

Hard evidence might be the size and character of cracks in a damaged wall, the reported findings of an environment assessment of a contaminated site, the rainfall recorded the day of the flood, video of a property taken from a drone or the floor covering in the room where the slip and fall occurred.

Soft evidence might be what the real estate agent told you before you bought the property about how the high, steep slope down to the sea was really stable – only to have a landslide undermine your house later.

In a sense, I took a briefing from news reports a few days ago – quite soft evidence – on the appearance of sink holes in ground near Vancouver and the need to evacuate 14 homes from a subdivision.  Out of interest, based on my experience as an engineering expert, I hypothesized on what was wrong at the subdivision.

One conclusion: The ground should not have been built on in the first place.  Another conclusion: It was built on but something went wrong during the geotechnical investigation and/or the acceptance and implementation of the investigation’s findings.(Ref. 3)

2. The expert’s experience Our experience is grounded in our professional discipline and will include our successes and failures. (Ref. 4).

For example, disciplines like civil, mechanical, electrical and industrial engineering.  Civil engineering has in turn branched off to structural, foundation, geotechnical and environmental engineering.

My discipline and consulting practice has evolved to focus on civil engineering and the civil engineering branches except structural.  I have also practised as a generalist engineer overseeing an investigation and retaining specialists like structural, mechanical and electrical engineers. (Ref. 5)

For example, I investigated the cause of a power tool accident knowing full well at the start that I would likely retain experts in the design and manufacture of the tool.  As it turned out, a video taken of the re-enactment of the accident indicated the likely cause of the accident.

In another problem, I called on a structural engineer to guide my investigation of the stability of a concrete block wall and also the floor beams in the building.  These were elements in the environmental assessment and remediation of a contaminated site, one of my areas of practice.

Experiences like these guide me in advising you during the merit assessment stage. Ask me about problems like these and I should be able to help you.

Tell me it was a concrete block wall that collapsed and I’m sure I can tell you why.  Tell me the size of the cracks in a wall and the component material and I’ll tell you the likely cause of the cracks.  If a structure subsided I’ll tell you the likely cause with great certainty.

If you come to me during the merit assessment stage about the cause of a traffic accident I’m not going to say anything.  I’m going to refer you to one of three specialists in this work depending on the location of the accident.

In the last four or five years right up to the last three or four months I’ve got very suspicious of the quality of Phase II ESAs (Environmental Site Assessments) in the Atlantic provinces.  My suspicions are based on peer reviews I’ve done and experience with a drilling company and comments by the owner.  If your merit assessment involves a problem in the environment my initial oral report will draw attention to the Phase II ESA if one was carried out.

If your problem has anything to do with earthworks, foundations, the subsoils, surface and ground water, flooding, the terrain in general, I’ve got a wealth of experience to call on including education and practice as a land surveyor.  My experience was gained in Atlantic Canada, offshore NS, out west, up north and overseas.

It’s the same with experts in disciplines like mechanical, electrical and industrial engineering.  After a few years the experience is in our gut.  It just comes out during your briefing.  It’s hard to suppress it.

It comes out with considerable confidence too because we know there is a lot of published information that can be reviewed during a merit assessment..

3. Published data The principal modes of failure of buildings and civil, mechanical, electrical and environmental engineering structures and their components have been studied at length and published. (Refs 6, 7 and 8)  Some of the published material is fairly general and leads us in the right direction but doesn’t tell us what’s at the end of the trip. (Ref. 9)  Some other is quite specific and gives us a good idea where to look for the cause of the problem.

Fairly General  Researchers in the US and Europe reviewed the causes of hundreds of structural failures – that’s 100s, plural – and categorized the primary causes as follows:

  • Human failure
  • Design failure
  • Material failure
  • Extreme or unforeseen conditions or environments
  • Combinations of the above

When professional engineers were at fault (human failure) the causes of failure could be classified as follows:

  • 36%…Insufficient knowledge on the part of the engineer
  • 16%…Under estimation of influence
  • 14%…Ignorance, carelessness, negligence
  • 13%…Forgetfulness, error
  •   9%…Relying on others without sufficient control
  •   7%…Objectively unknown situation
  •   1%…Imprecise definition of responsibilities
  •   1%…Choice of bad quality
  •   3%…Other

When the percentage distribution of the failures were summarized the US and European research found that almost half were due to errors in the planning and design of a structure and a third occurred during construction:

  • 43%…Planning and design
  • 36%…Construction
  • 16%…Use and maintenance
  •   7%…Others and multiple factors

For example, I reviewed research a few years ago that found many, possibly most, foundation failures were due to inadequate geotechnical investigation of the ground and foundation soils.  In the above classification, that would be human error – the professional engineer – and the 36% with insufficient knowledge category.

Another example; if you’re got an earthworks failure, like on a highway or in an industrial park, I would look through the 11 different stages of the life cycle of a structure.  Based on my experience I would quickly focus on the materials testing and inspection during the construction stage.  In the above, that would be material failure and the 14% ignorance, carelessness, negligence category.

In a sense, yet another example; it doesn’t help when you’re hypothesizing on cause to know the following but important fact: The National Research Council (NRC) have found that the most complex structure in the built environment is a basement and it’s foundations – not the most glamourous structure just the most complex and rife with potential problems. (Ref. 10)

I can imagine dozens of possible problems down in the basement.  Where do you start looking for a cause?  If no go-to-answer, based on your briefing and experience, it’s important to get this out at the merit assessment stage – in spite of the aggravation.

Quite Specific The American Society of Civil Engineers (ASCE) published a book that categorizes 209 causes of component failure in buildings. (Ref.7)  It’s interesting that the basement was not looked at in detail by the researcher and editor, David H. Nicastro.  I can imagine he didn’t know where to start considering that there are 100s of ways a basement can fail..

The ASCE categorization is a detailed source of information for an expert hypothesizing cause.  To get an idea of this resource, take a look at the blog I posted July 10, 2014 entitled “How many ways can a building fail and possibly result in civil litigation or an insurance claim”. (Ref. 6)  If you’re up for it, take a look at the ASCE publication itself (Ref. 7)

Following are two examples from my blog on how an expert might use the book:  The examples are 2 of 209 ways a building can fail:

The item in red is one of the 209 ways selected from the alphabetical list down the pages of the book.  The items in blue are column headings across the pages.    They note the distress in the building when the failure occurs, the materials affected, and one or more typical case histories.

Example #1, A client’s structure experiences:

  • Differential foundation settlement - the way in which his structure failed, the technical cause.
  • The distress to the structure is manifested as unwanted movement and distortion.
  • The materials and systems affected by this movement are the structural systems and foundations.
  • case history in Nicastro’s book is the differential settlement of the temporary foundation support of a bridge deck during construction.

Example #2, A client’s structure experiences:

  • Corrosion - the way in which a component failed, the technical cause.
  • The corrosive distress to the structure manifests itself as an unsightly appearance
  • Affecting the component’s materials, the metals.
  • Case histories in the book include a steel masonry shelf, and reinforcing steel in a concrete wall façade.  Both corroded with the infiltration of rain water.

Brief Summary

This is the kind of published data - 

  • exhaustive categorizing of failures, like 209 for a building 
  • good evidence on the primary causes of failure
  • the percentage distribution during the life cycle of a structure, and
  • the percentage distribution of errors professional engineers make -

that allows an expert,

  • based on your briefing and his experience,

to orally report during the merit assessment stage on the cause of a failure or accident or the basis of a claim.  It’s a preliminary oral report, that’s for sure, but more than a hypothesis, a guess.  The expert’s initial oral report comes from good evidence.- your briefing, his experience and published data.


  1. Merriam-Webster dictionary, on-line, February 2019
  2. Cost management of expert services. Posted January 31, 2019
  3. What’s wrong with this (sink hole) picture near Vancouver? Posted February 20, 2019
  4. Petroski, Henry, To Engineer is Human; The Role of Failure in Successful Design, Random House, New York, April 1992
  5. American Society of Civil Engineers (ASCE) Guidelines on Forensic Engineering Practice
  6. How many ways can a building fail, and possibly result in civil litigation or an insurance claim? Posted July 10, 2014
  7. Nicastro, David H., ed., Failure Mechanisms in Building Construction, ASCE Press, American Society of Civil Engineers, Reston, Virginia 1997 (Readily available by interlibrary loan from Memorial University, Newfoundland)
  8. Janney, Jack R., ed., Guide to Investigation of Structural Failures, American Society of Civil Engineers (ASCE) 1979 and 1986
  9. Built Expressions, Vol. 1, Issue 12, December 2012, Argus Media PVT Ltd., Bangalore, E: info@builtexpressions.cominfo@argusmediaindia.com
  10. Swinton, Michael C. and Kesik, Ted, Performace Guidelines for Basement Envelope Systems and Materials, National Research Council of Canada Research Report 199, pp 185 October 2005


What’s wrong with this (sinkhole) picture near Vancouver?

I was surprised at the news last week about the evacuation of 14 homes in Sechelt, on the Sunshine Coast near Vancouver because of sink holes and unstable ground.

What’s wrong with the picture is why such unstable ground was developed and built on in the first place if the risk was known.  Sink holes as large as an estimated 15 feet across and 3 to 4 feet deep in one news picture if typical are an obvious sign of unstable ground.

A geotechnical investigation – a well developed applied science – had been carried out and the risk identified according to news reports.

Sink holes not unusual and easy to investigate

Sink-hole-prone ground is not unusual in nature.  We got unstable ground like this in the Atlantic provinces.  There’s lots of sinkholes in the Bahamas where they’re called banana holes because banana plants grow in them.

A neighbourhood of 14 homes is about the size of my neighbourhood, and compact and the ground easy to investigation.

Geotechnical investigation identifies ground that is susceptible to sink holes like this.  The ground can be natural or due to the works of man.  It also identifies the different layers of soil and rock beneath the ground – the stratigraphy in geology – and the areal extent of the different layers.  It determines the physical properties of the materials forming the layers and their susceptibility to conditions of interest – sink hole development in this case.  Finally, it checks out the depth to the ground water and where it’s flowing.

Was the risk of building a house high or low?

Did the geotechnical work really conclude that the risk was 10% – possibly a low number to some?  Or did the work miss something which seems likely as evident by the evacuation?  How was the 10% calculated?  A probability analysis was not mentioned in the news.

It occurs to me that I wouldn’t build a house in an area where there was a 1 in 10 chance of my house being undermined by a sink hole.

Easy to investigate and improve the ground

Ground terrain like this can be improved.  It’s called ground improvement in engineering and is a well developed technique.  But it can be expensive involving lots of geotechnical work and construction work.

These kinds of investigative and improvement techniques are so well developed and understood in engineering that it’s motherhood.  The ground may be complex but finding this out and doing something about it is fairly straightforward.  Not building on the ground is one solution.

Simple, preliminary investigation

There’s a list of geotechnical techniques in the Appendix.  They are roughly in the order they might be carried out.  You can repeat some depending on what you’re finding.

One of the least expensive at the beginning of an investigation is a good walk-over survey of the ground.  This would be accompanied by a study – before, during or after the walk-over, or all three – of published topographic and geologic maps of the area and published aerial photographs.  New and old sink holes like those reported would be seen in a good walk-over.  An engineer experienced in terrain analysis could also pick out big sink holes on aerial photographs even those taken from 1,000s of feet high.

Such a walk-over and study are standard procedures in geotechnical investigation.  They’re cast in stone.

Video and stills taken from drones 10s and 100s of feet high have been available for a few years now.  They have been invaluable in my work.  Sink holes and unusual features on the ground show up well in aerial video.

Before drone photography I hired a small plane and had the pilot fly low over a site as I took photographs of the ground.

These preliminary techniques would be standard at the beginning of a geotechnical investigation of a site like the one evacuated near Vancouver.  The results would indicate if more expensive investigative work was justified like that mentioned above and listed in the Appendix and how to plan and do it.

Investigation and/or use of findings questioned

Of course, good and thorough geotechnical investigation must be followed up with good use and implementation of the findings.  The evacuation would seem to call into question the investigation and/or the use of the findings.  What’s wrong here is that something went wrong and shouldn’t have.


There are many techniques that could be employed during a geotechnical investigation.  I’ve used all of them in my consulting engineering practice at different times over the years:

  1. Terrain analysis using published aerial photographs from high flying aircraft – 1,000s of feet high
  2. Walk-over surveys and examination of the terrain on foot
  3. Studying published topographic, superficial (soil) geology and bedrock geology maps of the area
  4. Terrain analysis using published Lidar mapping of the area
  5. Terrain analysis using video and stills taken for the purpose from low flying drones 10s and 100s of feet high
  6. Studying contour and topographic maps prepared for the area
  7. Carrying out and studying a geophysical survey of the area
  8. Carrying out and studying ground penetrating radar (GPR) surveys of the area
  9. Drilling boreholes, measuring the thickness of the different layers of soil and rock, testing the physical properties of the soil in-situ and sampling the soil and rock for laboratory testing
  10. Testing the physical properties of the soil and rock in a laboratory
  11. Analyzing the stability of the ground using the data on the different layers of soil and rock obtained during the geotechnical investigation


How to manage the cost of dispute resolution and expert services

How a party engages a forensic expert affects how well costs are managed.  The best way is easy.  It involves starting early and reporting often.  It also involves learning about the forensic investigative process the same as experts are expected to learn about the judicial process.  Do this and you and your expert will understand one another.  Frequent reporting is essential to effective cost management..

The following summarizes the best way to manage costs:

  • Engage an expert early,
  • on a simple fee basis,
  • with frequent oral reporting
  • on the evidence-to-date,
  • the cost-to-date,
  • the estimated-cost-to-complete, and,
  • if required, a written report.

You’ll go through some tasks several times until you’re done.  It’s easy, and cost management proceeds nicely when you follow this routine. The process is commented on as follows:

1. Engaging an expert early can be as simple as talking with one at the merit assessment stage.  You can’t benefit from an expert’s knowledge until you talk with an expert, and the sooner the better.  If nothing else, brief him on the issue and get his off-the-record thoughts.  Most experts don’t mind giving a bit of time to something like this.

Perhaps engage him more formally to read some documents and/or visit the site.  Do this if the two of you perceive technical issues that could impact the dispute or forensic work and would need to be investigated.

Engage early: You really don’t want to take a case or pay out on a policy if the technical issues don’t support the position of the parties involved, or the parties can’t afford the cost of an investigation.  Experts sometimes see embarrassing situations when we’re engaged late.

(You can engage an expert in about eight different ways.  All the way from getting one to briefly give some factual data without analyzing it to retaining an expert to peer review and analyse the work and written report of another expert you retained earlier. (Ref. 1))

An expert can give a preliminary estimate of the cost to investigate the issues based on other forensic work he’s done – a rough order of magnitude of costs if nothing else.

During your initial briefing and talk with an expert you might also get a feel for the evidence that could be found during an investigation and where it might lead..

In a sense, at the merit assessment stage you’ll get your first oral report on

  • the evidence-to-date – the experts initial thoughts on this,
  • the cost-to-date – the expert’s charges for reading some documents, and
  • the estimated-cost-to-complete – the expert’s preliminary estimate of cost to investigate the issue.

before you’ve even decided to get involved in the issue.

While this is going on, you will gain some understanding of the dispute resolution and forensic engineering investigative processes.  There’s more information in the references on the nature of forensic engineering (Ref.2), the steps in the forensic engineering process (Ref. 3) and the difficulty estimating the cost of forensic investigation (Ref. 4).

At the end of the day, engaging an expert early will enable you to engage with him or her only as long as required by the judicial process and the needs of the parties involved in an issue.  And this decision will be based on good evidence.

2. Engaging an expert on a fee basis is the most effective way of managing the cost of dispute resolution and forensic work.  This is because it’s very difficult to estimate the total cost of this work at the merit assessment stage and should not form the basis for retaining an expert. (Ref. 4) The difficulty estimating costs is handled with frequent oral reporting on cost.

Nor should you pay too much attention to dollar-differences between the hourly fees of the experts you might consider engaging.  The fees of experts in Atlantic Canada are similar as they are elsewhere in Canada and in the New England states. (Ref. 5)  The qualifications and experience of the expert are far more important.

3. Get frequent oral reports on everything found at each stage of the dispute resolution or forensic investigation.  There are many stages in these processes and many opportunities to review evidence and cost. (Refs 3 and 6)

Get your expert’s thoughts

  • after you brief him at the merit assessment stage,
  • then again after he reads some of the documentation,
  • after he takes a look at the site,
  • studies all of the documentation,
  • does some work at the site
  • does some laboratory testing,
  • after he does some research,
  • after he … well, etc., etc.

and on and on for as many of the stages of a forensic investigation or dispute resolution justified by the evidence..

You’ll talk a lot but you’ll manage the cost of the issue well, based on the evidence-found-to-date, the cost-to-date and the estimated-cost-to-complete the investigative process.  When these line up with the requirements of the judicial process and your party’s interests you’ll bring the forensic investigation to a close based on hard evidence – lots of data plus costs.

4. Evidence-to-date

An expert is collecting hard and soft evidence all the time.  He’s

  • carrying out standard investigative tasks,
  • following leads,
  • journalizing and thinking-on-paper,
  • developing a time-line of tasks carried out, why he did them and the data and evidence he got, and,
  • ever alert to promising side-lines to the time-line,
  • analysing the data and evidence,
  • drawing tentative conclusions,
  • tweaking his hypothesis as to cause and
  • inching closer all the time to formulation of an opinion as to cause or the way forward in a dispute.

You can get the expert’s thoughts and the evidence-to-date at many and minute stages of an investigation.

As well, it may not be well known but the probable cause of quite a few different types of failure and accident in the built environment have been identified and published.   Tell an engineering expert what happened and the damage and, based on published material and experience, we can tell you possible causes. (Ref. 7 for example)

5. Cost-to-date

Experts book their time and expenses daily.  You can get cost-to-date whenever you like and as often as you like.

You can get costs at each stage and task of the forensic investigation and dispute resolution, and each stage of the judicial process.  The expert may not have updated evidence at all stages but he’ll have updated costs and expenses on a daily basis.

6. Estimated-cost-to-complete .

You can also get increasingly accurate estimated-cost-to-complete the forensic work whenever you like and as often as you like.

It’s well understood in project and cost management that the further along you are in a process the more accurate the estimated-final-cost.  This is because the more stages of a project or investigation you complete the more information you have for estimating cost and the more accurate the estimate.

7. Get a written report, if required

At this stage of the process, you’ll have lots of information on which to base a decision about getting a written report.  The sooner you decide the easier it is for the expert to estimate the cost of a written report, and the lower the cost .

Leave it for a year and the expert has gone onto other cases and disputes.  He must come back to your file and review the evidence and everything that took place during the investigation before he can plan and write the report.

I solve this problem to some extent by keeping a detailed time-line on What i did, Why I did it, and The data and evidence I got.


There is a very simple and effective procedure for managing the cost of dispute resolution and forensic expert services.  The simple, stepped procedure is easy to follow and not high tech by any stretch.  Some of us are engaged in it now and we like it, and our clients do too.

It starts by

  • engaging an expert early,
  • going through the simple steps as itemized and commented on in this blog, and
  • frequent oral reporting.

It ends when you decide, based on good evidence and the cost-to-date, that the requirements of the judicial process and the parties involved have been met.

The procedure is based on well developed, decades old project management methods..  These methods can be applied to dispute resolution and expert services as shown in this blog.


  1. How to retain an expert in a cost effective way. Posted November 30, 2018
  2. What is forensic engineering? Posted November 30, 2012
  3. Steps in the forensic engineering investigative process with an appendix on costs.  Posted July 15, 2013
  4. Why the difficulty estimating the cost of forensic engineering investigation?  Posted September 1, 2013
  5. An expert’s fees and forensic engineering investigation.  Posted July 5, 2016
  6. A bundle of blogs: A civil litigation resource list on how to use forensic engineering experts.  Posted November 20, 2013
  7. How many ways can a building fail, and possibly result in civil litigation or an insurance claim?  Posted July 10, 2014


What’s coming in dispute resolution and claims processing involving high-tech car accidents?

I can’t help but wonder what’s in store for the parties involved in high-tech, sensor-dense, autonomous car accidents.  Compound my wonder with new drivers whose training did not include winter road conditions.  Car dashboards are pretty with all those control lights but I wonder if they instill overconfidence.

(Autonomous cars – cars that drive themselves.  You just sit there and monitor the sensors)

How bad is it?  A friend drives a five year old Honda Accord that has sensors to indicate how close he is to an object when backing up.  We tested and the sensor incorrectly indicated he was about twice as far from my car as measured – 0.5 metres compared to an actual 0.25 metres.

Those sensors from a lower-tech age are quite simple.  What about others designed to keep you from drifting over the line and into the next lane?  The sensing cameras work well when you can see the lines but what about when the lines are covered with snow or dirt?  What about that distracting, warning Ping! Ping! when you’re trying to avoid potholes or drive just off the noisy track worn in the pavement over the years?

What about those braking sensors when you get too close to the car in front?  I’m scared to think what happens when they malfunction..

We’re in high-tech transition and accidents will happen like they did when air bags and seat belts first came out.  They’re reliable now but they weren’t at the start.  I wonder about the reliability of the sensors on today’s high-tech cars..

I thought these questions during a recent meeting of CATAIR, the Canadian Association of Technical Accident Investigators and Reconstructionists.  CATAIR is an association of serving and former police officers, consulting professional engineers and others who figure out how motor vehicle accidents happen.

We got together a few days ago in Moncton, New Brunswick.  We were there for a regular meeting with an agenda that included identifying training courses for the national meeting in Halifax in August, also for a talk by Ed. Goodfellow on drugs and driving.  Ed is Chairman of CATAIR for the Atlantic Region.

CATAIR arranges courses for its members on the reconstruction of traffic accidents.  New courses are sought or developed, or existing courses refined for reconstruction involving high-tech car accidents.  There is a learning curve associated with the refined methods.

I also believe time must pass and data collected to optimize the accuracy of the methods.  The methods are somewhat empirical – based on testing and experience   They rely for their increasing accuracy on test data from investigations – data that is still coming in.  The test data is used to refine the methods.

Some of the technology on new cars is quite advanced so the data for refining accident reconstruction methods must be limited to some extent, like that for airbags and seat belts at the start.

I can’t help but wonder about the increasingly complex disputes and claims that are surely resulting as cars add more sensors.  And the questions that might be raised about the accuracy of the expert’s methods.


  1. Reade, M. W. (Mike) and Becker, T. L. (Tony), Fundamentals of Pedestrian/Cyclist Traffic Crash Reconstruction, Institute of Police Technology and Management (IPTM), Jacksonville, FL 2016
  2. Civil litigation, forensic engineering and motor vehicle accident reconstruction.  Published September 22, 2015
  3. Is your traffic accident investigator well trained, experienced and “accredited”?  Published February 23, 2016
  4. “Seeing is believing” at a meeting of traffic accident investigators.  Published March 4, 2016
  5. If you  can measure it you can manage it, even if it’s a real mess like a car or truck accident.  Published June 23,, 2016
  6. Forensic assessment of traffic accidents.  Published October 26, 2016


How does an expert engage with a party to a dispute or a forensic investigation?

I was struck recently by the different ways experts engage with the parties to a dispute or those needing a forensic investigation.  I counted eight (8) different ways in comments by experts I consulted.  Some good and conforming to well regarded project management practices, others not so much.  How an expert is engaged affects how well costs are managed.

(See a list in the Appendix of the different parties that could be involved in a dispute or forensic investigation)

Seeing how it’s done now drove home the need for principles governing the cost management of dispute resolution and forensic investigation involving experts.  I’m identifying these principles and will post them later.

Early last month I sent a draft of the principles to experts and practitioners in different fields and asked them to review it.  These people included colleagues in engineering, traffic accident investigators, several civil litigation lawyers, a town planner and a published author.  I got good comments and suggestions and I’m incorporating these where relevant.

The reviewers’ comments indicated several ways experts engage with the parties to a dispute.  I’ve listed these below.  The methods vary from project management techniques, as characterized by frequent reporting of cost-to-date and estimated cost-to-complete, to methods that risk the expert being perceived as agreeing to a fixed price for his services. There’s not a lot of order to the following list and I’m sure it’s not exhaustive – it’s just an indication of how experts engage with clients in Atlantic Canada::

  1. Fee basis after the retaining party briefs the expert, the expert reads the documents and then estimates the cost of the forensic investigation.  Frequent updates on current costs and estimated cost-to-complete.
  2. Fee basis.  No reporting.  No cost estimate.
  3. Engage for the budget set by the retaining party, after learning the budget and the party’s theory of the case.
  4. Fee basis if the client has taken the case on a fee basis.  Declines the commission if the client has taken the case on a contingency basis.
  5. Fee basis and frequent oral reporting to the party on the findings at successive stages of the forensic investigation, and after being instructed by the party to carry out each stage of the investigation.
  6. Fee basis after all investigation is complete and all damage repair and remediation is done and all costs accurately known.
  7. Fee basis for preliminary investigation like reading documents and a visual examination of the failure or accident site sufficient to estimate costs for subsequent stages.  Then do successive stages as directed by the retaining party.
  8. Fee basis plus frequent reporting of current and estimated future costs.

This list begs the question:

  • Why the parties to a dispute or forensic investigation don’t engage with an expert early,
  • on a simple fee basis,
  • with frequent reporting of the evidence-found-to-date,
  • the cost-to-date, and
  • the estimated cost-to-complete?

If how an expert is engaged affects the cost of dispute resolution and forensic work then the bulleted procedure is effective – engage an expert early and get frequent oral reports on everything.  And engage an expert only as long as required by the judicial process and the needs of the party.


Parties to a dispute or a forensic investigation can include one or more of the following::

  1. Advocates and civil litigation lawyers
  2. Insurance company representatives
  3. Claims managers and consultants
  4. Insurance adjusters
  5. Owners of damaged property
  6. Builders and contractors
  7. People injured in accidents in the built and natural environments

Advocates, insurers and property owners, become aware!

I initially thought Buyer beware! as a title for this blog but that would be a poor choice of words because you’re not at risk of being cheated when you retain a forensic expert.  You are at risk of thinking an expert knows everything

And related, also at risk of misunderstanding the tasks a forensic expert must carry out in conforming to good practice when investigating a failure or accident.  Misunderstanding leads to crankiness as experienced by a couple of my clients.

You need to learn a little something about these tasks.  And why s/he must do them, and why it’s difficult to estimate the cost of some of them.  If we follow the evidence, we don’t even know about some of these tasks until our boots are on the ground.

Learn something about the following:

  • The building or civil engineering structure involved in the expert’s work
  • The stages and tasks in a forensic investigation

Become aware of the following:

All buildings and civil engineering structures in the built and natural environments have basic components that experts can name for you.  For example, they all have foundations, and also beams and columns.  And do you know?  A structure’s basement – like your house basement, for example, or that of a multi-story building - is the most complicated component of all – not very glamourous, just the most complicated. (Ref. 1)

All forensic engineering investigations have basic stages and tasks that are described in simple, non-technical language on this site and in engineering guidelines. (Refs 2, 3 and 4)  Some examples: 1) The document-review stage, 2) The visual-examination-of-the-site stage, 3) The recording-the-as-built-condition-of-a-component state, 4) Noting the as-failed-condition-of-a-structure stage, and 5) In a slip and fall accident, testing-the-skid-resistance-of-a-floor stage.  And all are carried out to an engineering standard of care.

We can estimate the cost of known tasks with varying degrees of accuracy – from easy and accurate to very difficult and quite inaccurate. (Refs 5, 6)  It’s the unknown tasks that crop up when we follow the evidence and look under the next rock that cause grief for all parties involved in a dispute.

The following nice people thought I knew everything:

Example #1: A client was surprised that I met with a contractor on site and charged a fee for this.  I was there to brief the contractor on the project and confirm how he would tackle the several stages involving different structures.  It was somewhat of an exotic project and nowhere to be found in the engineering textbooks.  I can specify an end result but it behoves me to make certain the contractor knows how to get there.

“I thought you knew everything!” my client remarked.  A nice way to be seen but we don’t know everything – we do know how to figure things out though.

Example #2: Another time a client was surprised when I charged for “researching” an issue -  safety criteria in a slip and fall accident.  There’s little guidance in the building code on this type of problem but lots of literature in North America and Europe.  I had to figure out how it applied to my particular case.  Again, “I thought you knew everything!”.  Nice thought.

Example #3: I’m trying now to determine if the site of an old fuel oil spill is still contaminated.  The spilling stopped about 27 years ago when the underground storage tanks were removed.  It’s fairly easy to learn the direction the oil flowed when it was carried away by the groundwater.

It’s something else to learn where the oil ended up and if the ground is still contaminated at that location.  I do know that natural attenuation has reduced the amount of oil in the ground but whether or not to an acceptable level is difficult to determine.

Natural attenuation is a complex process and there’s little or no expertise readily available because the problem doesn’t crop up often.  Should I get compensated for trying to find an expert in eastern Canada, the USA or farther afield because “I don’t know everything”?

(Natural attenuation involves microorganisms in soil eating the oil – it’s food to them.  There are five processes in natural attenuation but this is a main one)

Example #4: Somewhat related were the geotechnical investigations I carried out for new wharf and breakwater construction in harbours on Canada’s east coast.  About 27 investigations over several years.  My clients wouldn’t cover my expenses to travel to a harbour and reconnoiter conditions before estimating the cost of the work.

For example, reconnoiter the sea conditions we had to work in – sometimes quite exposed and dangerous -, investigate coastal conditions from which we had to launch a barge with a drill rig onboard, and check out the possible foundation soil conditions as exposed along the coast.

Surely I would not be expected to “know everything” about a harbour without seeing it and talking with the local fishermen?  And surely It’s not unreasonable to charge a fee for this?


When I suggest you learn a little something, I don’t mean you should learn a lot and pass a test.  Just gain some understanding and become aware of the tasks an expert must carry out, and to the standard of care for the time and place.

The recent case, Example #1, where I met the contractor on site consisted of seven big tasks.  Three quite large, different tasks plus three less-big tasks that prepared site conditions for a main task.  The main task also had a poorly defined scope that made matters worse.  All big tasks with expertise in the area but none that are done on even a half yearly basis, year after year.  And when the seven tasks were lumped together, this type of seven-big-task project was unusual for this area.

I would hardly expect you to learn much about a project like this but learn something and that it’s demanding of an expert’s time, including figuring-out and occasional research time.

Learn a little something about “the nature and methods of forensic engineering investigation” like it says in the masthead of this blog site.  Also the structure(s) involved and its components.  Forensic experts can give you a good understanding in most cases, except when we’ve got to follow the evidence and don’t know what we’re going to find until we get there.


  1. Swinton, Michael, NRC-IRC and Kesik, Ted, PhD, University of Toronto, Performance Guidelines for Basement Envelope Systems and Materials, Research Report 199, pp 185, National Research Council, Canada October 2005
  2. Steps in the Forensic Engineering Investigative Process With an Appendix on Costs.  Posted July 15, 2013
  3. American Society of Civil Engineers (ASCE), Guidelines for Failure Investigation, 1989
  4. Janney, Jack R., Guide to Investigation of Structural Failure, ASCE, 1986
  5. Difficulty Estimating the Cost of Forensic Engineering Investigation.  Posted July 23, 2013
  6. Why the Difficulty Estimating the Cost of Forensic Engineering Investigation?  Posted September 1, 2013


  1. Lewis, Gary L., Guidelines for forensic engineering practice, ed., ASCE 2003
  2. A Bundle of Blogs: How to Manage the Cost of Civil Litigation Involving Experts.   Posted August 31, 2017



How to retain an expert in a cost effective way

If you include peer review – good case insurance – you can consult with an expert in eight (8) different ways, from least expensive to most expensive, according to the technical needs of the case. (Refs 1, 2)  Really, only four (4) basic ways plus peer review.

Judiciously selecting the best way is one key to managing the cost of civil litigation.  You still got to manage your costs as distinct from the expert’s costs.

If you briefly confer with an expert, at the case merit assessment stage, you can, in a sense, add a ninth (9th) way.

These different methods are described below.  And there’s a nice, nine-item list at the end to help you see how easily the different methods follow on one another.

You must think about how and when you retain an expert because most failures in the built environment are small or medium-sized, not catastrophic and newsworthy – and not affluent either. (Ref 3)   Yet, regardless of case size, most failures and injuries require a thorough forensic investigation consistent with how the expert is retained and what s/he is asked to do.  You can always start small and expand the investigation as.the evidence comes in, if this seems justified.

Peer review of the expert’s work regardless of how he is retained is not so so necessary, not one of the basic ways, but it is good insurance – and cost effective for that reason alone. (Ref. 1)

In the past, experts have been retained in one of two ways:

  1. Consulting expert
  2. Testifying expert

Today and in future – almost without exception – experts will serve as consulting experts in the resolution of disputes rather than testifying experts.  This is because of changes in civil procedure rules governing experts.  The changes are designed to expedite resolution of disputes and reduce the number of cases going to trial.

(I attended Expert Witness Forum East in Toronto last February and learned that 98% of cases in one area of dispute were settled out of court.  I can’t remember the area but know it wasn’t engineering and science; even though the great majority in these fields, percentages in the mid-90s, are also settled out of court)

The consulting expert will submit one or the other of the following two basic reports according to Counsel’s instruction.  Ideally, these reports would be submitted at several stages throughout a forensic investigation, starting at a preliminary, even a merit assessment stage, to keep Counsel informed as to what the evidence is finding and the cost to date:

  1. Oral consulting expert’s report
  2. Written consulting expert’s report

The oral report can also be presented in one of two ways:

  1. Factual oral consulting expert’s report
  2. Interpretative oral consulting expert’s report

factual report gathers together all the data from the office, field, and laboratory investigations and submits the raw data to Counsel – without analysis and interpretation.  It’s used now in the science and engineering fields.  For example, in the geotechnical investigation of ground and foundation conditions at a new building site.  I was introduced to this type of reporting while practicing for a time in Australia and England.

An interpretative report analyses and interprets the raw data, draws conclusions and formulates an opinion on the cause of the failure or accident.  The report can be quite comprehensive, particularly in a complicated case.

The cost of a factual oral report is easier to estimate and control.  The cost of an interpretative oral report is more difficult to estimate.  Sometimes very difficult because you don’t know what you’re going to find at the site of an engineering failure or accident if you follow the evidence, (Ref. 4)

factual oral consulting expert’s report to retaining Counsel could be quite inexpensive compared to a written report to the requirements of civil rules.  A peer review of the factual oral report could also be relatively inexpensive.  The peer might discuss the facts with the expert – orally – and the investigation supporting these.

For example, I gave a factual oral consulting report on a power tool accident after I videotaped the victim reenacting the accident and after the tool was examined for wear but before investigating the adequacy of the design and manufacture of the tool. Counsel decided against further investigation based on my factual oral report.

Other examples: A colleague who reconstructs traffic accidents said he frequently gives oral reports on his findings.

Similarly, an interpretative oral consulting expert’s report could be relatively inexpensive with or without a peer review compared to a written report.  More expensive, of course, because of the interpretative element, but still less than a written report.

The written report can also be presented in one of two ways:

  1. Factual written consulting expert’s report
  2. Interpretative written consulting expert’s report

The relative costs of these two ways of writing a report on the forensic engineering investigation are apparent – less for factual and more for interpretative, and a little more still for peer review of either.

A summary of sorts

So, the cost of retaining an expert increases from least expensive – a factual oral consulting expert’s report without peer review, to most – an interpretative written consulting expert’s report with peer review.

It’s no surprise that an interpretative written expert’s report is one of the most expensive if it’s remembered that “An expert’s report is a critical, make-or-break document.  On the one hand, a well-written report will make testifying later at discovery and trial much easier … On the other hand, a poorly written report … can turn discovery or trial into a nightmare …” (Ref. 4)  And, I might add, turn questioning and rebutting the report before discovery into a cakewalk, a tsunami, if the report is distributed to all parties.

How you retain an expert – there are eight (8) different ways – is one key to reducing the cost of all cases, affluent and less affluent alike.  You can’t lose, if you manage your own legal costs properly, as I’m sure you do, with so many cost effective ways to retain an expert.

And also, like I said, there’s another way still, possibly the best way of all, the ninth (9th) way: Briefly talking with an expert at the case merit assessment stage.  Retaining an expert at this stage, for a few dollars. would be sort of like a preliminary factual oral consulting expert’s report – the most cost effective way of all and the best return on money spent on an expert; possibly even better than peer review.

Here’s how the different ways of retaining an expert appear in a list – from least expensive to most expensive – if we include conferring with an expert at the case merit assessment stage:

  1. Preliminary factual oral consulting expert’s report (at the case merit assessment stage)
  2. Factual oral consulting expert’s report
  3. Factual oral consulting expert’s report plus peer review
  4. Interpretative oral consulting expert’s report
  5. Interpretative oral consulting expert’s report plus peer review
  6. Factual written consulting expert’s report
  7. Factual written consulting expert’s report plus peer review
  8. Interpretative written consulting expert’s report
  9. Interpretative written consulting expert’s report plus peer review

A bit repetitious but I think helpful in deciding how to retain an expert in a cost effective way.

I did not include testifying expert in this blog because this role for an expert is much less likely in future – a few percent at most across all areas of dispute.


  1. Eureka! Peer review is good case insurance. Posted November 16, 2018
  2. How experts are retained in civil litigation is changing and the changes are good for counsel and the justice system. Posted May 1, 2014
  3. Principles Governing Communications with Testifying Experts, The Advocates Society, Ontario, June, 2014
  4. Reducing the cost of forensic investigation – it’s being done now by default not by plan. Posted September 22, 2014
  5. Mangraviti, Jr. James, J., Babitsky, Steven, and Donovan, Nadine Nasser, How to write an expert witness report, Preface, Page xiii, SEAK Inc., Falmouth, Mass. 2014


  1. Peer review in forensic engineering and civil litigation. Posted November 26, 2013
  2. A bundle of blogs: A civil litigation resource list on how to use a forensic engineering expert. Posted November 20, 2013


Eureka! Peer review is good case insurance

Peer review of an expert’s work is good case insurance against a summary  investigation, a careless analysis of the data, invalid conclusions and/or a poorly formulated opinion on cause.  And if all’s good, then it’s good insurance against delay in resolving the dispute and taking up the court or tribunal’s time.

And if a forensic investigation was omitted then peer review and identification of the technical issues is good insurance if the review finds you’re out on a limb – it’s nice to know where you’re at if you’ve got to backtrack.

(Summary as in “done quickly in a way that does not follow the normal process” – not thorough. Ref. 1)

By definition: Peer review is a process by which work (such as a scientific or engineering study, investigation or report) is checked by one or more experts in the same field to make sure it meets the necessary standards before it is published or relied on. (after Ref. 1) It can be as simple as getting an independent expert to simply read the report of the investigating expert.

Also by definition: Insurance is a means of guaranteeing protection against loss.  For example, “The peer review is your insurance against the loss arising from a summary forensic investigation or no investigation at all.”. (after Ref. 1)

I reflect on the above when I learn of failures and accidents in the built and natural environments that are well beyond the case merit assessment stage without benefit of an expert’s insight.  Not even a reading of the documents and a walk-over survey of the site – relatively quick and inexpensive forensic engineering tasks..

I had the Eureka! moment recently when I was following up on the status of a case after consulting with an advocate on the need for an expert to look into the matter.  Initially we discussed the circumstances of the problem and confirmed I was qualified to investigate it.  I was remiss at the time in not inquiring about the stage of the civil litigation.  I was surprised during my follow-up to learn that the case was in discovery.

Oh boy, what to do this late in the game?  I found myself typing my last sentence in an  e-mail suggesting peer review -  it just came out of the blue, the Eureka! moment - “Peer review is good case insurance”.

I know about peer review in forensic engineering but never thought of it as insurance.


By way of refreshing your understanding of peer review in forensic investigation you might read one or more of the blogs listed below in the references that I posted in the past.  They’re all quite informative, if I do say so myself, particularly Ref. 4 on peer review costs.  If nothing else, that one could save you money in litigation involving experts.  My blogs are also well referenced to the engineering and scientific literature on peer review so lots of good reading there too.


  1. Merriam-Webster dictionary, November 10, 2018
  2. Peer review in civil litigation and civil litigation. Posted November 26, 2013
  3. Peer reviewing an expert’s report ensures the justice system gets what it needs. Posted January 15, 2016
  4. Peer review costs can be controlled. Posted January 22, 2016
  5. Peer review pays off – 17 years later. Posted May 5, 2018


Reliable forensic evidence from drone photography; Aerial photos from way-down-low

I continue to be excited about using drone photography during forensic investigations.  The engineer and former land surveyor in me loves the wealth of accurate data in photographs taken a few 10s to 100s of feet above a site where a structure failed or a person was hurt.

We’ve always had photogrammetry in engineering – using photographs taken from airplanes flying many 1,000s of feet above the earth to identify and measure features on the ground.- but we get more and better data from drone photos and get it quicker and cheaper.  The potential uses are something else:

Use #1: Investigating traffic accidents: An engineering colleague routinely sends a toy drone aloft, a 100 feet or so, and takes a photograph of a traffic accident site that he is reconstructing. (Ref. 1)  He sees his site from this angle right away and it guides his investigation as he does his field work.  He can also get a print of his drone photo for his engineering report..

Use #2: Conferring with clients: I conferred with a client a few months ago while both of us had a CD of aerial video of his property uploaded on our computers.  I had mailed the CD to him a few days earlier.  He commented on features on the ground relevant to my investigation of his failure.

In one case he gave the history of the ground at one location – cows drank from a former dug well there in the past – that was important in confirming the depth to the ground water beneath the site.  At the time I couldn’t quite believe what i was hearing about the cows and the dug well – there was no evidence of this when I was on site..

Use #3: Getting data on a site: I emailed a drone photograph to a client recently and asked him to identify the location of buried structures on his property.  Structures like two underground fuel oil storage tanks (USTs), – which leaked oil in the past – a drilled water well, two dug wells, a septic tank and a disposal field.  He did this then emailed the marked up photograph back to me a few hours later.  He used Paint, a program on PC computers.  It was all so quick and inexpensive.

Use #4; Getting BIG Data:: The height or altitude of the drone above the ground when a photograph was taken has always been of interest to me.  Robert Guertin, Halifax who takes my aerial video, found a program that gives a wealth of data on each photograph.  The data includes the height of the drone when the photograph was taken, angle of the photo shot below the horizon, bearing of the view with respect to North and the GPS location, all important data in forensic work.

Use #5: Getting low cost data:  I get the scale of drone photographs now from the known size of objects in the photographs.  Like the length and width of a building or the distance between the lines on a highway.  The scale of the photograph I sent to my client a few days ago that he marked up with Paint is 1″ = 40′.

I can check the scale of a drone photograph by setting out ground control before taking drone photographs, like photogrammetry-of-old.  Ground control is nothing more than points set out on the ground a known distance apart and height above sea level.  I used sheets of white paper to mark points on a site I was investigating in Cape Breton.

Use #6: Photographing hard to get at damage: I recently suggested to a firm who needed an expert that we could record the condition of a damaged wall with a drone photograph.  Later I could measure and analyse the damage in detail and get an idea of the cause – measuring like I do now of the ground but of a vertical surface rather than a horizontal surface.  No step ladders, staging, labour and lots of expensive time needed.  .

Use #7 Replacing expensive site surveys:  The drone photograph with a known scale is certain to replace the need in the future for a site survey by a land surveyor, and be far more detailed, less expensive and quicker.  Site surveys measure the size, location and elevation of objects and features on the ground.  Conventional site surveys can be time consuming and expensive.

Use #8: Seeing a site in 3D: I’m working with Robert to see if we can get a stereo pair of drone photographs of a failure site and using these to view a site in 3D like we’ve always done in photogrammetry-of-old.  Software likely exists now for viewing drone photographs in 3D.  If it’s out there we will find it and I will use it during my forensic investigations.  In the meantime we’re trying to do it ourselves.

(A stereo pair are two photographs overlapping by about 60%.  When viewed with a stereoscope – sort of like eye glasses – the site appears in 3D)


What more do you want from simple drone photographs?  Name it and the potential for getting it.is almost guaranteed.  Honestly, with all due respect, you or your expert would be remiss if you did not get drone photos of your site.  Your expert would not be conforming to the changing forensic investigative standard of care.


  1.  A kid’s toy drone can photograph the site of an engineering failure, a personal injury or a traffic accident.  Posted September 12, 2018