By Jim Duff
NOTE: This column appeared in the Nov. 9, 2011 Gazette Vaudreuil-Soulanges:
Readers may recall our front-page stories in June, 2007 about the worrisome condition of the Ile aux Tourtes bridge. It all began with call from Norm St. Aubin. He’d been passing under the bridge when he spotted a dangling steel cable, rusted through.
Our reporter Matthew Brett learned it was one of the post-tensioning cables installed after the bridge opened back in ‘66, supposedly to enable it to carry more weight. These cables are steel, four inches thick, running along both sides the entire length of the span in plastic sleeves supported by steel guiderails. They were installed in 1990-91, replaced and more added in ‘97.
We never got a straight story from the Ministère du Transport why, if those cables were thought to be necessary to enable the bridge to carry more weight, their condition wasn’t a matter of concern. Looking back, we can speculate it was part of the collective state of denial just now emerging in the leadup to the Charbonneau Commission inquiry into criminal collusion in the construction and engineering consulting industries.
We ran the original Frankenbridge story on our June 17, 2007 front page. The Montreal Gazette and the electronic media fell all over each other in their rush to debunk and ridicule our story. Their only source — the MTQ.
The week after our first story, St. Aubin took Matt and a boatload of structural engineers out to have a closer look. Their verdict: the bridge was in terrible shape and the modifications made it worse. One of those along for the ride was Kaare Olson, who designed the bridge. He took a long look at the way it had been widened and supposedly reinforced before saying “that’s not the bridge I built.”
We fought to get the 2006 inspection report. We were turned down. MTQ spokesman Mario St-Pierre told us we wouldn’t understand what it said. Don’t worry, he added — the next major inspection is in 2009 and with the work being planned, the Ile aux Tourtes bridge is good for another 70 to 75 years.
Four years later, almost nobody believes anything Transports Quebec says. The Charest government, fed up with having been caught in so many lies, ordered the MTQ to post all bridge inspection reports on the web. You’ll find them all, including the June, 2009 inspection of the Ile aux Tourtes Bridge, at http://www.mtq.gouv.qc.ca
The report is a 114-page diagnosis of all that ails the 45-year-old prestressed-concrete span with a poor maintenance history. It also suggests the bridge’s problems began with the addition of cantilevered decks on both sides, apparently without much concern as to whether the original 1966 structure could carry the weight. The accompanying 117-page PDF illustrates the delaminating concrete and rusting re-bar we described two years before that.
What I find mind-boggling is that Genivar’s inspection team agreed with Kaare Olson: “Une verification de la capacité en cisaillement des poutres fissurées en tenant compte de l’ajout d’étriers externes est requise afin de préciser le CEC. Un suivi de la fissuration des chaises est requis.” Translation: Keep a close eye on the cracks in the main beams, because the concrete’s shear strength may have been compromised by the addition of superstructure the bridge was never designed for.
Imagine adding a concrete balcony all around a highrise that was never designed to carry the additional weight and and you get an idea of the forces on the original girders and seats.
For motorists who use the bridge daily, there’s a clearer, more present danger summed up in the report’s observations about the road surface: “A significant accumulation of debris on the right-hand shoulder appreciably affecting the security of users (blowouts, projection of debris, etc.) could cause poor water runoff in the event of heavy rains.)
Draw your own conclusions, but these two findings say “stay out of the two outside lanes.”
You’ll find another observation throughout the report: Slack, corroded post-tensioning cables, always with an oblique reference to the work either underway or planned for next year. The impression I get is that the inspection team was so worried at what they found, they felt they had to cover their butts.
Do I believe the Ile aux Tourtes bridge is safe? Last week, I interviewed Mario St-Pierre, the same MTQ spokesman Matt talked to in 2007. He told me they’re planning to replace it by 2020. Four years ago, he told us it was good for another 70 to 75 years.
We’re learning that here in Quebec, steel corrodes and concrete crumbles faster than elsewhere on the planet — but eight times as fast? Welcome to the State of Denial.