Why did the City change it mind about converting the transitway overpasses to rail?
Instead of re-using them for the Confederation Line tracks, a number of them are being demolished.
Here’s the old transitway at Bayview (built, c1980), recently demolished:
The armoured slope below the end of bridge abutment was removed, revealing that the huge block of concrete sat on steel posts:
Bedrock is about 30′ down, so the steel posts were driven into the soil til they rested on bedrock. Presumably all was engineered to hold up the weight and vibrations from a gazillion OC Transpo buses on top.
Or was it?
Here’s one of those key steel beams, once it had been removed, that held up the abutment and in turn the bridge itself:
It looks like a prop from a Star Wars movie about a junkyard planet, not bridge supports that people depend on everyday for a safe drive home.
Let’s take a closer look:
All that corrosion and rusting away occurred in just 35 years.
I wonder if city engineers know how corroded the beams were. And how could they tell, its not like they have a window into the embankment to check on the steel. Like a lot of infrastructure it may not have been designed to be monitored or maintained. But then I didn’t study bridge engineering.
The new station and bridge supporting posts are made of reinforced concrete. These pillars go down 30′ to bedrock, and then 2′ into the bedrock, so they shouldn’t topple over either.
I wonder how much more of our 1970’s and 80’s infrastructure is rusted out?
Nearby is this NCC bridge on the Ottawa River commuter expressway. It has been sagging for years until the dip in the road became untenable. So a steel cribbing was put underneath to hold it up. For how long?
A bit further west from Bayview Station along the transitway the whole roadbed is held up by precast concrete panels forming a viaduct:
Each panel locks to the next one to make a smooth wall. It is prevented from bulging out or collapsing by … steel cables that run from these panels to the ones on the opposite side of the viaduct.
As long as the gravel fill in the viaduct remains dry and salt free, what could go wrong?
[no cheating now, don’t refer to the prematurely rusted out Champlain Bridge in Montreal which was built by the Feds to be kept salt-free but maintained by Montreal which did the cheapest thing, and dumped salt on it. Free infrastructure is always wasted or abused. I think that includes today’s federal infrastructure program too.]
Well, water and salt might have penetrated our transitway viaduct wall after all:
Presumably RTG engineers have dug into the gravel fill forming the viaduct once the transitway roadbed was removed. I wonder what they found?
Here is a pic, possibly from Dave Allston of Kitchissipimuseum, showing that viaduct under construction back in the 1980’s as the transitway slopes down from Bayview overpass towards the cut going to Tunney’s Pasture.
Last week we looked at that same section of road in the cut, which is on top of a giant concrete lid over a big sewer underneath. Nice to know repairs are being made:
Capital expenditures can last almost indefinitely if properly designed and maintained. But how is “out of sight” infrastructure monitored? City politicians are usually rewarded for deferred maintenance. Ultimately, taxpayers aren’t.
pictures above are by myself, Richard Eade, possibly Dave Allston.