How I got good forensic video in the spring, and you can too

I’m learning all the time – see below – about new methods of forensic investigation.  Also, hopefully, for my readers, increased understanding of the nature of expert work.  For example, aerial video from a drone has been a real eye-opener for me and some of my clients in recent years.

It struck me recently while walking my dogs in a forest that spring is a good time for taking aerial video during a forensic investigation.  For sure, fall as well.  You see through the leafless trees to a forest floor brightly lit by spring sunshine.  I can see my dogs off at a distance in the leafless forest why not the forest floor from above?

Even as I draft this blog I’m learning.  It occurs to me that a cloudy day would be even better – no shadows to confuse what you’re seeing on the ground.  A hardwood forest is best, of course, after the leaves have fallen.

For example: I flew over a leafless forest last spring during a site assessment case and got excellent aerial video.  You could clearly see a piece of gravel the size of a golf ball from 100 to 200 feet up.  The video was a dispute-resolution maker.

To be upfront with you though, it was seeing my dogs running in the forest that made me realize why I got good video last spring.

Another example: I had another case, a fuel oil contaminated site, that was in a dense hardwood forest that was a prime candidate for this type of aerial video.  It didn’t come to pass – the case went off on another tack – but I was ready to capture good video through a leafless forest.

Aerial video of fuel oil contaminated sites has been a game-changer for me in treeless terrain so why not in leafless terrain?

Why am I telling you this?  Because, if you’re processing a dispute or claim that involves an accident or failure in the built environment now is the time to get aerial video of the site.  If there are leafless trees on or near the site, go aloft now.  COVID-19 is no problem because it’s easy to keep your distance outdoors.

Chicken soup for the soul of a forensic expert

Some forensic investigations end suddenly and unexpectedly, reveal the simple cause of the problem and leave the expert feeling soooo good.  Others age us with their head-scratching complexity.

I thought this – and to tell you about it – on reading some stories in one of the chicken-soup-for-the-soul books, The Magic of Moms.  They are warm, feel-good stories that end nicely just like some forensic investigations.  They’re also well written, reason enough to read and learn from them for writing expert reports.

Some examples of chicken-soup-for-the soul forensic investigations

Example #1 One of my investigations involved re-enacting a fatal motor vehicle accident.  The accident happened when the car struck an obstacle in the road at a speed of 50 mph.  I decided to re-enact striking a similar obstacle but initially at a lower speed.

I had safety procedures in place but the car behaved so erratically at 20 mph that I knew I needed even more safety procedures.  Like a rescue crew that could get me out of an overturned car.

Then the penny dropped and I realized that if the obstacle could potentially cause an accident at 20 mph what was likely to happen at 50 mph?  I stopped the investigation with a clear understanding about the cause of the accident, and a good feeling too.

Example #2 I was retained to investigate the stability of a steep slope in an established residential area.  Was it unstable and if so why?

Slope stability analysis can be expensive and time consuming.  Lots of data collection, mathematics and number crunching.  Engineers like this sort of thing but first, boots on the ground and a quick, inexpensive visual examination.

I saw that a retaining wall had been constructed at the toe of the slope.  This would involve excavating the soil at the toe of the slope and possibly undermining it.  But did it?

I saw cracks in the ground in back of the top of the slope – a telltale sign – so it did slide down, at least in the past.  But, was it still sliding?

Examination of trees on the slope particularly saplings found that the trunks were curved, concave up-slope.  The trees kept reaching for the sky like they do as they grow, while the ground beneath their roots kept sliding down-slope.  No number crunching needed here; the slope was moving as I walked across it.  I felt good seeing this, and also glad to get off the slope.

Conclusion: The slope was unstable and this was due to construction of the retaining wall.

Example #3 I saw the same curved saplings on another slope stability problem indicating the slope was still sliding.  Not catastrophic fast sliding – not breaking-news fast – but sliding and unacceptable.

Example #4 Pie-shaped ground beneath a commercial building gave me that good soup feeling too.

I was retained to determine the cause of the foundation failure of a building.  The foundations were still subsiding years after construction causing cracks in the concrete building.  Precise surveys found 0.4 inches per year 10 years after construction.  Not a lot but too much for a concrete building.

A geotechnical investigation of the building site found that it was underlain by a pie-shaped soil and rock fill.  A few inches deep at one end of the building, 25 feet deep at the other end.  The  surface of a fill where foundations are placed subsides according to fill thickness.  More where it’s deep and less where it’s shallow.  And if it’s still settling after 10 years it means poor compaction during fill construction as well.

Strengthening the fill with cement grout fixed the problem.  None of this was inexpensive, but the forensic investigation was simple, determination of cause certain, the fix successful and the feeling good.

Example #5 I was retained to investigate the condition of a nail gun involved in a bloody accident.  Simple examination of the gun found no worn parts.  I was about to retain experts from away in the design and manufacture of nail guns when I decided to have the injured worker re-enact the accident.  He did this and I got video from three different angles with a simple iPhone and texted it to my client.  We talked about how the accident might have happened based on the re-enactment and that was enough.  It was a simple forensic investigation that ended quickly and it felt good.

I can cite other examples but that’s enough.


My frugal Mom would be proud of me hearing the penny drop, recognizing that the forensic investigation had determined cause sooner than expected, and saving money.





COVID-19 and forensic engineering investigation

It struck me one morning while walking my dogs that forensic engineering investigation is not prevented by COVID-19.  Experts often work alone as principal investigators conferring with other specialists as needed.  Many of the most experienced experts are sole practitioners.  We already “work from home” in a sense and have for years.

Expert sole practitioner “working from home”, alone

We take briefings “from home”, get documents by courier and study, visually inspect a site and “kick the tires”, research the literature, photograph and video a failure or accident site from a drone, measure the site, etc. (Ref. 1)  All done by the expert, alone.

This amount of forensic investigation is often enough for an expert to determine cause – not always, but often.  Even to go through several iterations of cause (hypothesis modification in the scientific method) like I did recently for a mini-flood. (Ref. 2)  An expert does go on site at the first opportunity though.  It’s a no no, not to.

Expert sole practitioner “working on site”, with other specialists

For sure, if it’s a catastrophic failure or accident when other specialists must be called in then a forensic investigation might need to wait – at least to finalize after the expert’s initial tasks noted above are done.  Possibly a wait of only a few short months, however, in light of the opening-up-lock-down talk of late.


As regards waiting, I’m thinking about the staging of a motor vehicle accident in a road safety assessment case I did recently.  Too many people involved to finalize that in a hurry if it had occurred during COVID-19.

Also the John Morris Rankin accident re-enactment I did a few years ago.  Also the nail-gun accident re-enactment I did not long ago.  And a bridge collapse the cause of which hung on a topographic survey of the site and the height of the flood waters at the time of the collapse.  And a building foundation failure and remediation.

There were just too many people involved up close and personal during forensic investigations like these.

But, back to the expert sole practitioner “working from home”, alone

The cause of large cracks in the exterior wall of a recently constructed multi-story building?  This could be stated with great certainty by an expert based on a telephone briefing on wall construction and crack size and configuration.  COVID-19 be damned; the expert would work from home and determine cause.  I did not get retained on this one because of a hiccup in the process but it would have been a motherhood type of assessment from my “work from home” office.


  1. A Bundle of Blogs: Aerial video of insurance and forensic sites taken with cameras mounted on drones.  Posted October 31, 2019
  2. The scientific method in action determining the cause of a mini-flood.  Posted April 30, 2020