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The Spey Bay Bridge has decided to have a bit of a lie-down...Tired viaduct
Saw that on the news a few minutes ago. Timely because I was reading this earlier:
Basically we (as a country) have done bugger all in the way of maintaining existing infrastructure assets for decades and ALL those chickens are now coming home to roost. When maintenance is finally identified, it's almost always urgent and therefore very expensive - it's also not very glamourous, not the sort of thing a local MP can really get behind.
Building a new bridge or road or whatever on the other hand is very glamourous so that's where all the effort goes. And then in 40-50 years time, that too is falling down.
Anyway, that is "only" a cycling and walking bridge, my prediction is it'll stay like that for 7 years before finally being replaced with something half as good.
Seem to recall Italy had a similar attitude to bridge inspections and maintenance
It must have been an awful sight,
To witness in the dusky moonlight,
While the Storm Fiend did laugh, and angry did bray,
Along the Railway Bridge of the Silv’ry Tay Spey,
Oh! ill-fated Bridge of the Silv’ry Tay Spey
And so on (credit to one McGonnagall, W)
The failure looks to me like scour causing the upstream pier to collapse. It's hard to inspect for this requiring cameras/divers and the correct conditions - the river bed is probably pretty dynamic. It's easy in comparison to inspect above water level. Hard to know what the inspection regime was, but you can be sure the pier foundations weren't done frequently.
From some photographs it looks like the river main channel may have moved towards the left hand bank over the years, assuming the main span was the once the channel centre, so putting this pier at increased risk.
Progress now probably decided by a thorough inspection to see how viable the rest of the structure is. I don't know the spot , but the dropped spans will need dismantled and lifting out, needing access and a crane pad built. At least once that is done such works might help enable constructing a replacement. I wonder what the clear span is between the two neighbouring intact piers?
Basically we (as a country) have done bugger all in the way of maintaining existing infrastructure assets for decades and ALL those chickens are now coming home to roost.
Thats really not true. Whether we do enough to keep ahead is another matter but its doing alot of very busy busy and over worked people a disservice. If this bridge was a road or railway bridge it would likely have been under considerable scrutiny for the below reasons.
The failure looks to me like scour causing the upstream pier to collapse. It's hard to inspect for this requiring cameras/divers and the correct conditions - the river bed is probably pretty dynamic. It's easy in comparison to inspect above water level. Hard to know what the inspection regime was, but you can be sure the pier foundations weren't done frequently
I agree about it being scour.
The river is exceptionally dynamic and that pier should have been on the floodplain which until recently it was.
Scour inspecting ie looking for holes isn't that useful. Its like an MOT you can inspect one day then the foundas wash out the day after.
While we might inspect for scour. Proactivity is the key here. We typically identify the risk of scour occuring, comparing the calculated scour depth potential and comparing against foundation type, material and depth. And the and do something about mitigating it.
Local authorities are super stretched though. That bridge was always going to be a liability as soon as it started moving, the original works included river stabilisation in 1885 it would appear that was the first failure here.
Guess what i do for a living.
Guess what i do for a living.
Ice cream man!?
I couldn't be an ice cream man. There would be nothing to sell after about 9am
Sounds like you may have a similar job to me joshvegas.
http://www.forgottenrelics.org/bridges/spey-viaduct/
Interesting further reading, such as piers constructed as concrete filled iron tubes to bedrock, making scour less likely. Also the comments about struggling to keep the Spey in its preferred channel.
It must have been an awful sight,
To witness in the dusky moonlight,
While the Storm Fiend did laugh, and angry did bray,
Along the Railway Bridge of the Silv’ryTaySpey,
Oh! ill-fated Bridge of the Silv’ryTaySpey
And so on (credit to one McGonnagall, W)
Bah. You beat me to it on the other one.
Oh christ have i found another colleague on here?
Interesting further reading, such as piers constructed as concrete filled iron tubes to bedrock, making scour less likely. Also the comments about struggling to keep the Spey in its preferred channel.
Thats not a wet pier though my money os on that os not how they built that pier.
I went down the rabbit hole a bit on this one, thanks to the internet and the upload age- basically got captivated by aerial images because it's like a standard grade geography textbook, you can see <everything>- gravel beaches, meanders, even some proper ox bow lakes, and clear as day old river courses. Add some old maps and google earth's historic mode and you can see the river moving ever closer, there's drone footage from just a year ago that shows the pier near the river but still on the bank and dry (except in flood because of course it's still a flood plain). And last month it had a couple of feet of water under it in flooding but was still completely surrounded by trees.
And then literally just in the last month (and I assume just in the last days because the bridge'd fall pretty much as soon as it happened), boom entire bank finally washes away and the pier ends up literally in the middle of the river.
(random fact I really liked is that you can see today that the river doesn't really go under the main span, so you think obviously it's moved over time... but it turns out, they built the main span on a dry bit and then diverted the river under it. Old man Spey took exception to that apparently.)
I'm having this conversation like 5 different places, I got all fascinated! Hmmm. Are you Fit-Pomegranite?
That would be one of my personas
That would be one of my personas
My take was the same as waderider, Josh and northwind.
While scour assessments may not be perfect. Having eyes on the structure on a routine basis would have helped but I don't know Moray councils inspection regime.
I'm not involved in scour and underwater assessments but we are required to comment on the general conditions of water courses.
I can't see that being rebuilt, not with the state of council finances.
Having eyes on the structure on a routine basis would have helped
100%
I just meant actually looking scour is difficult. Like you could send diver to have a poke about, everything is gtg. Then the next day a flood come thtough and boom have an undercut pier for your troubles.
That bridge would default to high risk by either National Highways or Network Rail guidance and subjected to increased monitoring for sure until something could be fonevabout it.
It would be an interesting project. I would favour putting something really modern to replace the lost spans.
I'm not an expert, but I was a user
****ing website again.
I give up.
It would be an interesting project. I would favour putting something really modern to replace the lost spans.
There's an interesting example just a bit west where the Findorn passes Forres. A more modern structure was erected to extend an existing bridge when the river took a couple of detours.