I read the report in yesterday’s Chronicle Herald about flying pieces of metal injuring four people on a popular ride in Yarmouth.
It occurs to me at this distance that this should be a fairly easy failure to investigate with a visual assessment by perhaps an experienced mechanical engineer. For certain, to at least enable a tentative statement of cause.
This is because the surfaces from which the metal came loose are likely to be exposed to view. And because there are likely to be other units (chairs?) in the ride apparatus that are identical with the metal still in place. This would afford a before and after comparision of the in-place condition of the pieces of metal. This type of comparision can yield good evidence.
(A failure in engineering occurs when something in the built environment doesn’t perform properly)
A visual assessment doesn’t sound very technical but it is always valuable and sometimes all that is necessary. And it is an essential part of the main steps in the failure investigation process:
- Acquisition of data
- Analysis of data
- Formulation of opinion
One time, I investigated the reason a piece of ice fell from a structure and struck and injured a person. My investigation was based almost entirely on a visual assessment of the exposed surfaces of the structure. I did this to some extent from a distance with binoculars and a camera with telescopic lens.
I also was able to compare the condition of the part of the structure involved with other unaffected parts of the structure and other structures in the area that were the same.
I analysed the data – largely taken from a visual assessment, formed my opinion, submitted my report, and, I understand, a dispute that had been ongoing for several years was resolved within a few months.
This situation with the falling ice seems very similar to the situation in Yarmouth with the flying pieces of metal.
At the very least, an initial hypothesis could be formed as to the cause of the problem based on a simple visual assessment. This hypothesis could then be investigated by more detailed forensic engineering investigation, if this in fact is necessary.
The Nova Scotia Department of Labour are investigating and I’m certain we’ll know the answer soon enough.
References
American Society of Civil Engineers, Guidelines for Failure Investigation, 1989
The Chronice Herald, Thursday, August 2, 2012, page A6