I was retained to investigate the cause of an accident involving the plaintiff using one of his tools.  People have been killed using this type of tool, it’s that dangerous.  The plaintiff believed there was a defect in the tool.  Graphic photographs of his injuries would certainly lead you to believe that – an initial hypothesis.

I was asked to peer review a report by another engineer and to examine the tool for wear sufficient to cause the accident.

The other engineer reported test-using the tool but, as evident in his report, not during a re-enactment of the accident.  He found a few things wrong with the tool but nothing to suggest it was defective.

I was surprised that the engineer did not re-enact the accident considering his stated years of experience investigating accidents.

I reviewed the report, researched howhis  the tool operated and examined the exterior.

I video taped the plaintiff re-enacting the accident and recorded his explanation of how he was injured.  I had him do this three times just to be sure and video taped his demonstration from different angles.

Evidence from the video and the interview was quite revealing as to cause but questions arose when this evidence was considered in light of evidence from the graphic pictures of the plaintiff’s injuries.

I retained a tool repairman to dismantle the tool and visually examine the interior surfaces for wear and defects.  He found nothing.

At this point in my investigation:

• The nature of the injuries depicted in the pictures suggested one cause
• The re-enactment suggested a different cause
• The tool operated properly according to the repairman, supporting the different cause

The tie-breaker – justifying modifying the initial hypothesis on cause – were comments by the plaintiff during his interview on how he was using the tool coupled with how the tool operated.  Turns out he was using the tool in the most dangerous way, but one of several ways it could be used.  Also turns out that the material he said he was using didn’t exist as he described, except as a special order.  A similar, readily available material suited to the job he was doing could explain the contradiction raised by the graphic pictures.

To summarize the tie-breaking bullets:

• The plaintiff said that he was using the tool in the most dangerous way, supporting the different cause noted above
• The material he probably was using could explain a contradiction in the graphic injury pictures, also supporting the different cause

Based on the evidence, I modified my initial hypothesis that a defect caused the accident to believing that the plaintiff caused the accident by his actions when using the tool in the most dangerous way.

***

A spoiler?  As noted above, the plaintiff reported using the tool in the most dangerous way.  But, on being retained, I was given the tool rigged to be used in one of the safest ways.  This might have spoiled my modified hypothesis, but didn’t – the tool had passed through at least four sets of hands by the time I got it.

My client decided against further forensic investigation.

***

Design, manufacture/construction and maintenance/repair are three main stages in development and use of an item in the built environment, like a tool.  My investigation covered maintenance/repair when assessing if the tool in this incident was defective.

Retaining experts in design and manufacture to examine the tool would be a stage in a forensic investigation like this.  However, taking this step would not be justified considering the strength of the modified hypothesis and the cost of experts in design and manufacture.

My investigation several years after the incident cost money.  It would have cost less, as would the civil litigation in general, if I could have interviewed the plaintiff several days after the incident, or after my client took the case, and video taped him re-enacting the accident.  I’m certain the evidence from such simple tasks would have cast the merit of the case and the worth of the file in a quite different light.

Case take-aways

My take-away from this case is to get my iPhone out of my back pocket and video tape a re-enactment of an accident ASAP and have the victim describe it.  It might be rough – iPhone forensic video – but this quick and dirty stuff can pay dividends in a forensic engineering investigation.

My client’s take-away? Possibly an old saw – retain an expert early preferably during the merit assessment stage or a few days afterwards and save money on civil litigation.

Sinkholes, like the one that undermined the house in Falmouth, Nova Scotia last week, are a serious issue for subdivision and lot developers.  As reported in the newspapers, the risk of sinkholes forming in an area can be known from published maps. (Refs 1, 2)  And the cavities in the ground associated with sinkholes can be found – before construction.

Sinkholes start their life as roofed-over cavities at some depth in the limestone, gypsum and salt deposits beneath an area.  The cavities get bigger and the roof gets thinner as rock like this dissolves in the ground water.  In a sense, the cavities “migrate” to the ground surface and eventually break through as sinkholes.  The fairly precise size, location and depth of cavities can be determined beforehand.

The technology for locating cavities in rock is well developed and has been around a long time.  It’s called ground penetrating radar, GPR for short, and it’s well known to experienced geotechnical engineers.  I used GPR years ago to locate cavities beneath an airport runway on South Andros Island in the Bahamas.  The same technique is used for locating unmarked graves.

It sounds technical but all it involves is sending radio waves into the ground and analysing what is reflected back.  There’s nothing too exciting in the data that comes from uniform soil or intact rock.  But lots of excitement in the data from a cavity, a well-recognized anomaly to the GPR operator – and a potential sinkhole beneath a building. The remote sensing, non-intrusive technique is not unlike CAT scans and MRIs in medicine.

The type of potential sinkhole I was looking for at the airport is called a banana hole. So named because banana plants grow in the sinkholes once the cavities break through the surface.  A banana hole/sinkhole can be seen in the runway by an inbound pilot but not the roofed-over cavity just before it breaks through the surface.

Geo engineers investigate the adequacy of the foundation soil and rock conditions beneath a site where someone wants to build something – like a house, for example, or a bridge, dam, or airport runway.  The conditions would not be adequate if there was a cavity beneath the building site.

GPR would not normally be used on a building site in the Atlantic provinces, nor in Canada for that matter.  But it certainly should if deposits of limestone, gypsum and salt are noted when the engineer checks the published geology of the site – an important and standard task in a geo investigation.  These types of rock with their inherent risk are not so common but they do exist as noted in the news report on the Falmouth sinkhole.

If there’s a risk and the technology is available to quantify it, and it’s not used, then it seems to me it’s a potentially litigious matter.

References

1. Falmouth: Sinkhole wrecks family’s house, pg. 1, The Chronicle Herald, Halifax, Tuesday, September 5, 2017
2. Geological conditions: Sinkholes not unusual in N.S.: Scientists, pg. 1, The Chronicle Herald, Halifax, Wednesday, September 6, 2017