Cindy Day’s grandmother predicted the weather the same way forensic engineers initially hypothesize the cause of a failure or accident – by ‘accumulated wisdom and careful observation‘. (Ref. 1)

I was struck by this as I read Cindy’s book, ‘Grandma Says’ – and the fact the two of them get their predictions and hypotheses right a lot of the time based on little evidence. This as confirmed by science in weather forecasting and more detailed forensic investigation in engineering.

‘Grandma Says is a collection of 80 weather-related sayings and prognostications about the weather based on traditional sayings and experience’. Most weather lore is based on careful observation of nature’s cycles or of animal behaviour. (Ref. 1)

I’m reading the book and noting which of Grandma’s 80 sayings are based on simple observation but well supported by science – so far, many.

For example:

• Morning dew on the grass, rain will never come to pass. That’s because the air temperature drops on a clear, windless night to the dew point – the point when the air is saturated with moisture. Condensation then occurs and appears as dew on the grass. These conditions exist in the centre of a fair weather system.
• If the dog is acting up, there’ll be thunder before long. This is because they can smell increased concentrations of chemicals in the air associated with a storm, like ozone which has a metallic scent. They can also hear thunder long before we do. My two dogs do that.
• It’s not snow, it’s poor man’s fertilizer. That’s because snow contains a lot of nutrients, like nitrogen, for example, and a lot of moisture. If the snow falls on unfrozen ground in the spring, the nutrients penetrate the soil and do some good, like fertilizer.

I’ve mentioned different times how an expert’s initial hypothesis – an educated guess – on the cause of an accident or failure is based on a (1) visual assessment of a site, (2) preliminary data and (3) experience. I’ve even ventured to estimate the percent probability that the hypothesis will be borne out by additional forensic investigation. (Ref. 2) This is the approach in both science and applied science (engineering).

For example, as mentioned in the following blogs:

• A Bundle of Blogs: Using visual site assessment. Posted January 25, 2021
• What can you get from a virtual visual site assessment of a retaining wall on the verge of failure? Posted November 13, 2020
• “Calibrating” a forensic expert. Posted June 23, 2020
• “Technical” visual site assessment. Posted September 4, 2012

I’ve demonstrated the application of experience and observation by hypothesizing the cause of failures reported in the news, and noted the potential for failures in the future – see the following list.

I study these failures to get more experience. The correctness of my educated guessing has been endorsed by local colleagues in engineering, and others away and overseas. We’re getting it right most of the time based on experience and observation – like Cindy’s Grandma.

For example:

• Condo collapse, Miami, Posted July 14, 2021
• Cost overruns, Ottawa Posted June 22, 2021
• Building collapse, London, Posted December 31, 2020
• Retaining wall failure, Ottawa, Posted November 13, 2020
• The potential for failure, Everywhere, Posted July 23, 2020
• Bridge failure, Edmonton, Posted March 25, 2020
• Crane collapse, Halifax, Posted September 20, 20019
• Bridge collapse, Italy, Posted October 5, 2018

Farmers, gardeners, outdoor people, dog owners and forensic engineers are all doing it – forecasting the weather and the cause of problems. If truth be told, I can imagine the young farm girl is alive and well inside Cindy Day, the meteorologist, and that she is still forecasting the weather, like Grandma did, on her drive to work each day.

For sure, Cindy’s checking the charts and hard data before going public with the weather forecast. But still having fun on the drive observing, estimating and learning based on wisdom and experience – like engineers do – and getting it right often enough.

References

1. Day, Cindy, Grandma Says, Weather Lore from a Meteorologist, Nimbus Publishing, Halifax 2012, 2013
2. The reliability of an educated guess on the cause of a failure or accident. Posted October 22, 2020

(Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada Posted July 28, 2021 ejorden@eastlink.ca)

What is hot-tubbing but group peer review? And if group therapy is good when we’re down in the dumps then group peer review – hot-tubbing – is good when we’re in dispute.

Hot-tubbing with experts and their reports is increasingly recognized as a good way to resolve a dispute. (Refs 1 and 2) If the reports were peer reviewed before they were taken into the tub, so much the better.

Hot tubbing involves experts retained by different parties to a dispute getting together, reviewing each other’s report and agreeing a single report. Also noting where they can’t agree. It’s getting more popular in Canada and the UK and is widely accepted in New Zealand and Australia. Not so much in the adversarial U.S. of A.

Peer review involves a similarly qualified person(s) thoroughly and objectively evaluating an investigation of something and the conclusions drawn. For example, the cause of a failure or accident in the built environment. Sometimes the persons involved are not known to one another. Peer review has been around a long time in science and increasingly relied on in engineering.

I thought, if both are good, get them together in the hot-tub – experts with peer reviewed reports. But watch carefully and don’t let them in unless their forensic investigations and reports have been peer reviewed.

It’s interesting, that as good as it is, the hot-tub process did not involve experts in it’s development. (Ref. 4) Get experts involved now in the hot-tub process and perhaps we can tweak it from the inside to another level of excellence.

References

1. Biased experts cured with a soak in the hot tub. Posted January 31, 2017 This is a real good read
2. “Hot-tubbing” experts reduce the cost of civil litigation and ensure objectivity. Posted March 31, 2018 Another good read
3. A Bundle of Blogs: On the need for peer review in forensic engineering and expert services. Posted November 19, 2019
4. Corbin, Ruth M., The Hot-tub Alternative to Adversarial Expert Evidence, The Advocates Journal, Spring, 2014 (Dr. Corbin is Chair, Corbin Partners Inc., Ontario)

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada July 23, 2021 ejorden@eastlink.ca)   

It’s easy for a forensic engineer to identify the probable cause of a failure in the built environment based on preliminary data – to give an initial hypothesis. (Ref. 1) Collapse of the 12-story Miami condo on June 24, 2021 is no exception.

We do this based on:

• A briefing by the client
• Reading the documents
• Our experience and observation over time

The briefing and documents in this case were news reports and photographs, an engineering report and a research report.

The collapse was not a disaster waiting to happen. It was a disaster unfolding over 40 years since construction of the condo in 1981. Slowly at first then real fast – the collapse. (Refs 2, 3 and 4)

What’s the evidence?

1. The condo was a reinforced concrete structure. Columns, beams and floors were made of concrete reinforced with steel for greater strength. Steel rusts in water and loses strength. (Ref. 5) You can see this type of construction underway in our towns and cities where ever there is a tall crane – for example, today on Prince Albert Road in Dartmouth, Nova Scotia.
2. An engineering study in 2018 found the concrete spalling – exposing the steel to water. (Ref. 3) The study reported major structural damage and ‘abundant’ cracking. Example locations included the concrete slab below the pool deck and in the parking garage. Cracking could be expected in the concrete columns, beams and balcony floor slabs.
3. The condo foundations were supported on limestone, reportedly soft and porous. (Ref. 2) Limestone is soluble in water – it dissolves in water. Think sinkholes in Nova Scotia and elsewhere.
4. The source of the water? The condo site was a former wetland on a barrier reef an estimated couple hundred feet inland from the ocean and a couple metres above. (Ref. 2) This means the groundwater – for certain, salt water – was in the limestone supporting the foundations and not far below. This is like the water level that you see in a dug well. This is a harsh (marine) environment for exposed steel and soluble limestone.
5. Another source of water? There were reports that the deck of the swimming pool and the floor of the parking garage were poorly drained. (Ref. 3) These wet surfaces would be near the level of the foundations that are supported on limestone.
6. A study by a professor at Florida International University found that the condo was sinking steadily since the 1990s. (Ref. 4) That’s what happens to condo foundations supported on limestone that is softening over time.

So, where’re we at with respect to cause?

The condo foundations were subsiding (sinking) on the soft limestone for years causing the columns above to settle – move downwards. Excessive foundation settlement is a failure in itself and certain to have contributed to the collapse, and possibly been the main cause.

This vertical movement of the columns stresses the steel reinforcing the concrete and the steel connecting the beams and floors above to the columns. This is the steel weakened by water over time – the structural distress reported in 2018.

In time, this movement over-stresses the steel causing the connections to break and the condo to fall down – collapse.

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That’s an initial hypothesis as to cause based on press reports and photographs – preliminary data for sure but still something. And better than nothing when seeking comfort at such a loss of life.

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(It’s interesting that the engineering study in 2018 did not comment on the foundations and the underlying porous limestone nor on the fact that the condo was sinking since the 1990s. Possibly because it appears to have been a visual structural assessment of exposed surfaces. Still, red lights if ever there were any – porous limestone and a sinking condo)

References

1. Where does an expert’s initial hypothesis come from? Posted February 25, 2019
2. Various news reports, pictures and video after the collapse on June 24, 2021
3. Report of a structural assessment by Morabito Consultants, Inc., Miami on October 8, 2018
4. Study of building subsidence by a professor at Florida International University, Miami
5. Why did the bridge collapse in Italy and how might Advocates have known this could happen? Posted October 5, 2018

(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada July 14, 2021 and updated July 18, 2021 ejorden@eastlink.ca)   

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