I was sorry to learn about the Regina design engineer, Scott Gullacher, being implicated in a bridge failure in Saskatchewan in 2018. I wasn’t too surprised. CBC News reported on the failure at the time. Then again on May 13 about the engineer facing a disciplinary hearing by the Saskatchewan Professional Engineering Association.
The bridge carried a rural road over the Swan River at Clayton, 300 km east of Saskatoon. It was supported on a piled foundation – screw piles. These are good like driven piles in suitable foundation soils that are determined during a geotechnical investigation. Except in this case the piled foundation failed causing the bridge to collapse a few hours after opening. Pictures of the collapsed bridge are striking at:
Surveys have found “that most foundations failures are due to inadequate geotechnical investigation”. (See Appendix) This type of engineering investigation determines the physical properties of the ground used in designing suitable foundations for support of a structure – a bridge in this case. (Ref 1)
Based on what I’ve read, it’s another example of the pushing and pulling among the vested interests with their respective bottom lines – both government and private. The tug of war this time over a geotechnical investigation of the foundation soil conditions – should we or shouldn’t we, spend the money?
Too often in situations like this the design engineer is caught in the middle of the quandary and seen as the arbitrator in the war. S/he knows an adequate investigation should be carried out.
What’s adequate? Only the geotechnical engineer knows for sure. Was a geotechnical engineer consulted in this case? Hopefully the disciplinary hearing will report on this – if they do their job properly.
- What is geotechnical engineering? Posted December 21, 2021
Long ago I learned “that most foundation failures are due to inadequate geotechnical investigation”. This was based on a study in England. The source was reliable enough that I referenced it in a chapter for a publication planned by the Canadian Geotechnical Society at the time.
The surficial geology in England is more variable than here; you can’t take a couple steps across a construction site over there without the soil conditions changing. Still, you’ve got to be careful in Canada too as the bridge failure attests.
(Google earth pictures of the river and bridge site might raise alarms about possible poor foundation soil conditions to anyone with a basic knowledge of terrain analysis. For example, I would suspect weak foundation soils on the bed of a meandering river)
There’s no glamour in the ground Karl Terzaghi said – the father of soil mechanics.
I’ve also got the idea over the years that construction engineers are happy campers when they get construction out of the ground – dirt doctors don’t mind being down there. Also that below ground construction is a disproportionately higher part of the project cost.
I’m not surprised the design engineer ran into trouble and strife on the Saskatchewan bridge failure, regardless of who is reported as responsible at the end of the day. He was there in the thick of it.
(Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada, May 25, 2022. firstname.lastname@example.org)