The announcement that the provincial government is planning to replace older aluminum railings on the Serpentine River bridge in South Surrey with a more up-to-date concrete barrier doesn’t mean the older design is unsafe, engineers with the Ministry of Transportation say.
A structural-engineering study of the fatal crash that sent a Honda Civic through one of the railings into the river last year found the barrier met the safety standards that were in place when it was built 50 years ago.
“The standards of the day are safe enough,” Lina Halwani, regional manager of engineering for the ministry’s South Coast Region, told Peace Arch News during a Feb. 20 briefing.
Since that briefing, Green party transportation critic Don Pitcairn, a South Surrey resident, has said the report confirms the bridge and others like it around B.C. – including the nearby Nicomekl – are “a disaster waiting to happen.”
The engineers, however, said the railings failed to keep the car from plunging into the river because they were designed to withstand a glancing blow, not a near-direct hit.
That kind of railing failure does not appear to have ever occurred before on a B.C. bridge.
Structural experts at Associated Engineering (AE) Ltd. reassembled the salvaged railings pulled from the river and tested identical undamaged railings and posts that were purchased when the bridge was built in 1961.
The AE tests showed that while the 50-year-old posts had become “brittle” and were not as strong as they were supposed to be due to “large amounts of porosity in the casting,” they still met the 1961-era Standard Specifications for Highway Bridges code set by the American Association of State Highway Officials.
The hollow aluminum railings were in better shape.
“As a result, the railing system used on Serpentine Bridge complies with all relevant requirements of the code at the time the railing was designed,” AE’s executive summary concludes.
According to the report, the barrier likely broke apart after the Honda hit one of the cast aluminum posts that support the railings, “colliding directly with the post over a small contact area.”
The report doesn’t say how the car came to hit the barrier at such a steep angle, but notes an RCMP collision reconstructionist suggested the car “rotated clockwise around its centre of mass” when it crossed the west fog line, then hit the railing.
In response to a question from PAN following the briefing, ministry staff said the findings suggest the car hit one side of the lane, spun out of control, then hit the same side again (A previous PAN story incorrectly said the car hit one side, then ricocheted into the other).
Current standards would require a different kind of barrier in the form of a continuous solid concrete divider of the type that was recently installed on two lanes of the four-lane Serpentine bridge, part of a widening project to accommodate a bus lane.
She said the ministry has decided to replace the aluminum railings on the other two lanes of the bridge with the same kind of concrete barrier.
Other high-traffic bridges of similar vintage, like the nearby Nicomekl, will be assessed and may also be fitted with updated barriers, she added.
Patrick Livolsi, regional manager for the ministry’s South Coast Region, said the vast majority of the 2,800 bridges in B.C. were built to the older safety standards.
Both he and Halwani stressed that the failure of the Serpentine aluminum railing under an unusual impact does not mean the older design is dangerous.
Asked if a modern bridge-barrier design would have prevented the fatal plunge, the engineers declined to speculate.
A woman in her 20s died in hospital following the Feb. 28, 2011 crash.