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.
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pictures above are by myself, Richard Eade, possibly Dave Allston.
Excellent post. That is some serious corrosion for a steel beam…
There is more evidence of salt corrosion along the Transitway, indeed in the Scott Street trench itself.
Tunney’s Pasture station has been completely demolished at transitway level. From the photos I’ve seen, there’s plenty of evidence that the red painted steel tubework and the stairs had suffered.
Elsewhere along the trench there has been an ongoing concreting program whereby the original rock cut walls are covered over in concrete. Both sides of the cut show ongoing deterioration, but it’s noticeably worse on the north face, which of course faces south and is exposed to the sun. But it’s not the sun that’s really at fault: all that salty slush spray from passing buses covers the rock walls, where the briney water (exacerbated by the sun on the north side) works its way into the limestone layers in a highly sped-up freeze-thaw cycle (compare that to the O-Train rock cut which is still about as solid as the day it was cut).
Salt-corroded deteriorating bridge structures, station infrastructure and rock cut walls: just a few more cost items we, the now-current taxpayers and the then-future taxpayers, can add to the list of costs imposed by the late 1970s decision to build busways rather than light rail.
David James put his finger on it. Rubber tired vehicles simply cannot function safely at higher speed on a surface that is not free of ice. That was never even a point of discussion when the transit way was planned. Had these hidden costs been identified it might have been more difficult to simply dismiss LRT. Also of concern is what RTG is responsible for when all these hidden failures are unearthed. What does their contract say? It is not correct to hide these issues which will likely come to roost on the taxpayers. No one seems concerned with the unexpected. If RTG had really covered all these risks their price would have been much higher. No I think we will wake up to a sad truth of “unexpected expenses” when all the mandarins and even elected officials who negotiated the original contracts are elsewhere.
And this same consortium is lined up for the next phase. Let us hope we do not simply extend the contract but learn from this first experience.
“Water ruins everything.”
Its slowly becoming evident that many parts of the first few Transitway segments were not well built at all. The bridge over the Rideau river between Hurdman and Lees station was in a lot worse shape than first thought and has required much ,more work than RTG first thought before its deck’s conversion to rail could begin. Many of the older stations were not in good shape. Tunneys Pasture for example was not torn down because they wanted it torn down to make construction of the new LRT station easier, it had to be torn down. You can see many of the bridge sections over the Transitway roadway had very poor reinforcement and was laid down with very poor quality concrete. One worker at Tunney’s told me the northern elevator shaft almost didn’t have to be knocked down and broken up. It was in such poor shape had they waited any longer to do the work it probably would have fallen down and apart all on its own. I was at Lincoln fields on the local platform waiting for the 16 Main Street Bus last winter when a section of glass slid off the roof along with the piece of ice that was sitting on top of it. You could see all the metal connecting pins and screws had either rusted or just been sheered off. A second look at the pieces still part of the roof structure showed similar fatigue.