The International Information Center for Geotechnical Engineers

Monday, 24 September 2018 01:00

Bridge constructed without geotechnical investigation directly collapses

Foundation failure leads to bridge collapse Foundation failure leads to bridge collapse.

The Dyck Memorial Bridge, constructed in the Rural Municipality of Clayton approximately 300km east of Saskatoon, collapsed just six hours after its opening.

According to officials, the bridge was built without any geotechnical investigation of the riverbed it was founded on. It seems that the soil under the foundation gave in and a row of piles sunk causing the collapse.

Rural Municipality of Clayton Reeve, Duane Hicks, initially stated that a geotechnical investigation wasn't feasible under the river. "You can't drill through water. You can't do it. You can't take underground samples," he mentioned. However, Hicks later admitted that drilling can be done under the river but it would raise the cost of the construction. "Well the fact of the matter is we don't have a heck of a lot of money," he said. He also claimed that experts told him to assume the type of soil beneath the river by drilling holes on each shore. According to Hicks, Inertia, the company responsible for the project, may not have drilled these holes on the shore. The company refused to make any statements to media.

Bridge-construction expert and engineering Professor at the University of Toronto, Paul Gauvreau, comments on the unfortunate incident: "I think it's irregular that a proper geotechnical program wasn't done for the piers in the water. And it is not correct to say that it can't be done in a river. It's done all the time. Perhaps for smaller bridges you can get by with a less extensive geotechnical program, but generally speaking you're going to have at least one test hole at the location of every pier including piers in the water," he said. Professor Gauvreau also argued about the cost of a geotechnical investigation: "A geotechnical investigation relative to the cost to build a bridge is not that expensive. It's being sort of penny-wise and pound-foolish by not doing the geotechnical investigation. It's not an insignificant cost but the point is that's not a cost that you can shave" he claimed.

The bridge is going to be reconstructed the next weeks by Inertia at no cost to taxpayers. According to Hicks, new longer piles will be inserted in the ground providing stability to the construction. "They're going to go down deeper. And just keep going down and down and down. I don't know what I could ask them to do differently quite frankly," he said. Bob McDonald, executive director of the Association of Professional Engineers and Geoscientists of Saskatchewan (APEGS), did not confirm that an examination will be conducted to penalize the responsible for the incident. He only said that the organization can perform an investigation if it receives a complaint or a request by the council.


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