We’re told by a reliable source the Athabasca River at Smith was the highest it’s been in 70 years on June 23 or thereabouts. That’s when it was only a metre or two below the bridge deck. Records exist, and in 1953 it was higher. It looks as if the old bridge came through the experience intact, although engineers will undoubtedly be taking a close look at it. Likely the shoring up the M.D. had done last winter helped.
A similar bridge over the Yellowstone River in Montana collapsed on June 24, sending rail cars carrying hot asphalt and sulphur into the water. The Yellowstone was running very high at the time. Officials aren’t saying whether the high water is responsible for weakening the structure, but others are less cautious. An engineer quoted in an AP article on the collapse says repeated high water events can weaken the support structures by means of scouring out the river bottom around the concrete piers. This is exactly what was happening to one of the piers on the Athabasca bridge. Shoring it up was the goal of the rip rap project around the pier that took place late this past winter.
The focus of all the stories on the Montana bridge collapse is on the hazardous materials; understandable, but the condition of the bridge goes begging. Photos suggest a whole concrete pier is missing, having apparently disintegrated, or tipped over. But none of the news stories say anything about it. And that’s not just our impression; the engineer who told us about it said the same thing.
Anyway, the good news at Smith is the water is down, the bridge is open for regular use, and no heavy trains with hazardous loads are passing over it. They are of course passing over the CN bridge just upstream. It seems to have come through the deluge intact as well, if the continued passage of trains through Slave Lake is anything to go by. CN got back to The Leader to say its bridge did not suffer any ill effects from the high water.
by Joe McWilliams