Solving mysteries from car crashes to stage collapses
From our 2013 Professional Schools issue
Before the hit series CSI, there was the Canadian documentary show Exhibit A, which traced the ways investigators had used high-tech scientific analysis to solve real-life crimes. As a teenager, Shannon Kroeker enjoyed the show so much she considered forensic sciences as a career. When it came time to choose, she opted for what seemed more realistic: mechanical engineering at Queen’s University. Nonetheless, at 33, she now spends her days doing detective work just like on the show.
Kroeker is a forensic engineer for the firm MEA in Vancouver, where she combines expertise in injury biomechanics (her Ph.D. involved prodding human tissue) with witness statements, photographs and medical reports to explain the impact of car crashes on human bodies. For example, how much did not wearing a seat belt contribute to an injury? She writes reports, usually for insurance company lawyers who are working to settle disputes. “When you’ve got all your clues and you have the ‘aha’ moment where you figure out what happened,” she says. “I find that really rewarding. It’s solving the mystery.”
Unlike their design-focused peers, forensic engineers work backwards to deduce what went wrong in fires, floods, plane crashes, product failures and building collapses.
Hassan Saffarini, a structural specialist with NORR Ltd., who has worked on everything from a 72-storey tower in Dubai to the revitalization project at Toronto’s Union Station, did high-proﬁle forensic work recently when he led a team investigating the Algo Mall collapse in Elliot Lake that killed two people. Their report concluded that decades of water damage had so badly corroded the weld on a steel connector holding up the concrete ceiling that it couldn’t withstand the pressure of a passing vehicle, a catastrophic problem inspectors missed. He can already see an impact of their work. “In other projects that are not even close to that kind of situation of the Elliot Lake mall, people are coming to us and asking for assessments of their buildings,” he says, adding that the Professional Engineers of Ontario now spells out in more detail what inspectors must do. “If our study contributed in any way to reducing the chance of something like that happening again,” he says, “that’s fulfilling in itself.”
Doug Perovic, a professor in the University of Toronto’s department of materials science and engineering, teaches what may be the only forensic engineering course in the country and has testified at dozens of trials.
When the stage collapsed before a Radiohead concert in Toronto in 2012, killing a drum technician and forcing the show’s cancellation, forensic engineers were called in by the various parties to the investigation. Perovic was hired by the band. “Luckily it didn’t happen during the show,” he says. “There would have been a lot of deaths.” After the collapse, the Ministry of Labour took photographs, made measurements, interviewed witnesses and put the twisted metal in a storage unit under lock and key. The engineers agreed on a series of tests for bad design, inadequate components or other potential causes. Perovic, who won’t comment on his findings, will eventually submit a final report, as will the other engineers. “If it looks fairly obvious what happened, there may be a quick settlement,” he says. “If it doesn’t look so obvious, we may need to go to court.” A conclusion may be months, even years away.
Perovic is often called in to testify in court. In a 1996 murder trial, a Pickering, Ont., man was accused of killing his 20-year-old ex-girlfriend and making it look like suicide. Perovic tested the electrical extension cord found around her neck and sampled wood fragments from the doorway it was tied to. His analysis strongly suggested she’d jumped. The ex-boyfriend was acquitted. “Witnesses might lie on the stand in a courtroom, but the fingerprints materials leave behind can never be untrue,” he says.
In a recent case in London, Ont., exploding glass-ceramic cookware had badly cut a man’s wrist while he was doing dishes. To test the cookware’s design, Perovic took four other pots from the same 1992-made set, along with similar newly made pots, and used chemical analysis, structural analysis and optical stereo-microscopy to look for defects like scratches. He also carried out thermal shock testing to simulate going from a hot stove to soapy water. One of the 1992 pots failed the thermal shock test. When it came time to testify, Perovic told the jury that the elevator they rode to the courtroom was built to carry 11 times the stated maximum allowable weight—a wide margin of error to keep them safe. With the pot, “the margin of safety was too low,” he said. “[The plaintiff] was using it in the way that was expected and it shattered, causing serious injury.” The plaintiff won $1.2 million. Perovic says it may lead to safer designs. “As an engineer and an educator, that’s the important thing: to learn from any mistakes.”