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Cambrian Storm Damage / Conwy Valley Flooding 02/20

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KNotts

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The Conwy river is tidal as far as Trefriw (hence the quay), so the newly-dredged river would still be full of sea water twice a day, and rainfall at spring tides would remain problematic.

(It was the arrival of the railway in Llanrwst in the 1860s that put the quay out of business, as it happens.)

Much of Llanrwst's flooding issues come from the dog-leg in the river just south of the town, before the river passes under the rail bridge. In times of heavy rainfall, the river can burst its banks here, and flow straight-on into the town. At that point, all the flood water is the wrong side of the railway alignment and held back from the river channel by the railway, hence its propensity for being washed out.

A very informative and interesting reply there, thank you.
 
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krus_aragon

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A very informative and interesting reply there, thank you.
You're most welcome.

Your mention of Trefriw Quay (ad my subsequent checking of dates) has left me wondering if the original station name of "Llanrwst and Trefriw" was chosen to coax trade away from the quays, as opposed to just naming it after any and all nearby settlements (c.f. Tal-y-Cafn and Eglwysbach station).
 

Llanigraham

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Now been told no trains Mach to Aberystwyth, and having seen the photos of Machynlleth I suspect Dyfi Junction is under water again.
 

Bletchleyite

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It really is proving a bad couple of weeks, isn't it? Much more like the issues in 2005ish which seemed to last all winter rather than the 2015/2016 one-off bad storm.
 

Llanigraham

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It really is proving a bad couple of weeks, isn't it? Much more like the issues in 2005ish which seemed to last all winter rather than the 2015/2016 one-off bad storm.

Somebody locally worked out that since Christmas we have only had 5 days with no rain! It's no wonder the ground cannot take any more.
 

Welshman

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Not only is the Conwy Valley line still closed, but the rr.buses have now been suspended due to flooding along the main A470 into Llanrwst.
 

PHILIPE

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At the moment there are a lot of people at Aberystwyth and other stations at the West End of the route trying to reach Shrewsbury or beyond and people at and approaching Shrewsbury trying to get to Aberystwyth and other locations at the Western end of the route.
The rail route is closed between Machynlleth and Shrewsbury due to flooding and now the replacement buses are unable to get through due to flooding in the Welshpool area.
 

Bletchleyite

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At the moment there are a lot of people at Aberystwyth and other stations at the West End of the route trying to reach Shrewsbury or beyond and people at and approaching Shrewsbury trying to get to Aberystwyth and other locations at the Western end of the route.
The rail route is closed between Machynlleth and Shrewsbury due to flooding and now the replacement buses are unable to get through due to flooding in the Welshpool area.

I'd suggest that the railway probably needs to be getting on the phone to local hotels at both ends...
 

Llanigraham

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This is the Severn valley just south of Welshpool, the railway line is just out of shot at the bottom of the picture:
SqOzvkP.jpg

The photo shows Welshpool Airport, which unfortunately is the HQ of Mid Wales Air Ambulance. Their unit is the small one right by the road.
There is a rail bridge over the Severn just out of frame and I've seen a photo elsewhere that shows the river level is only about 6" from the bottom of the beams. This is the same bridge that was damaged by flood water some years ago so they built 2 temporary stations either side and passengers walked over the bridge.
 

Belperpete

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Much of Llanrwst's flooding issues come from the dog-leg in the river just south of the town, before the river passes under the rail bridge. In times of heavy rainfall, the river can burst its banks here, and flow straight-on into the town. At that point, all the flood water is the wrong side of the railway alignment and held back from the river channel by the railway, hence its propensity for being washed out.
A good point. Awhile back I visited an area in Switzerland that had suffered severe flooding and washouts a number of years prior, and noticed that they had obviously invested a lot of money in straightening the rivers out to improve the flow. This is perhaps even more important than dredging, yet rarely seems to get mentioned in the UK as a solution. As with dredging, it will only work if there is somewhere downstream for the water to go.

Dog legs not only slow the flow of a river, but the reduced flow encourages the deposition of silt, which further restricts the flow. Those ruler-straight rivers I saw in Swtzerland may not have been particularly picturesque, but they looked to be doing the job.
 

Belperpete

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Buses are now able to run through but unable to call at Welshpool.
According to TfW Journey-check, the rail replacement bus services are now totally suspended:
Due to localised flooding in the Welshpool and Shrewsbury areas, the rail replacement bus service has been suspended.

Apparently the Severn is still rising at Shrewsbury, so it might perhaps be awhile before things get better.

Not much better on the buses. This from Lloyds of Machynlleth:
T2 will only run between Bangor and Dolgellau due to A470 closed at Mallwyd to Cemmaes
X29 and 30 service will be temporary suspended due to flooding at Llanwrin
T3 will not be able to serve between Corwen and Bala due to road closed and will travel down the A494.
T12 Currently suspend in Newtown. Unable to operate between Newtown - Wrexham due flooding
School buses will not operate-
30, X29,
Pennal- Mach
Ceinws - Mach 163
Mach - Ysgol Dyffryn Dulas 527
Miffordd - Ysgol Craig y Deryn 525
 

Y Ddraig Coch

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It might not need much in the way of repair. Looks like just ballast washouts this time?

That's all it needed earlier, this weekend just gone has been a shocker again for weather. Its just water on top of water already there, I don't know if it has got worse this weekend. I didn't make it up there this weekend but I know even the big main roads around the area where I live which are usually ok are underwater today. Even if just ballast that is needed, getting the water levels down to do it could be a long waiting game. Last night was especially bad.
 

Llanigraham

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As per Belperpete's posting above it has now got to the stage that Welshpool is basically cut off and travel across much of Mid Wales north of a line Rhayader - Leominster is almost impossible, even in a 4x4. The situation in my photo above has if anything got worse! And it has been raining all morning.
NR have also posted a photo of an embankment washing away, I think somwehere between Welshpool station and Buttington LX.
 

Meerkat

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A good point. Awhile back I visited an area in Switzerland that had suffered severe flooding and washouts a number of years prior, and noticed that they had obviously invested a lot of money in straightening the rivers out to improve the flow. This is perhaps even more important than dredging, yet rarely seems to get mentioned in the UK as a solution. As with dredging, it will only work if there is somewhere downstream for the water to go.

Dog legs not only slow the flow of a river, but the reduced flow encourages the deposition of silt, which further restricts the flow. Those ruler-straight rivers I saw in Swtzerland may not have been particularly picturesque, but they looked to be doing the job.

The straight rivers in Switzerland are hideous, and not great for the environment either.
Better (assuming downstream can take it) to build flood relief channels like Windsor or Exeter.
 

AndrewE

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That's all it needed earlier, this weekend just gone has been a shocker again for weather. Its just water on top of water already there, I don't know if it has got worse this weekend. I didn't make it up there this weekend but I know even the big main roads around the area where I live which are usually ok are underwater today. Even if just ballast that is needed, getting the water levels down to do it could be a long waiting game. Last night was especially bad.
They really need to be trialling an alternative: if every time they rebuild and reinforce an embankment it just washes out somewhere else a few months later you would think that they might twig that a cheap standardised viaduct might be a better (i.e. more resilient) repair, even if it costs a bit more in the short term.
 

Bletchleyite

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They really need to be trialling an alternative: if every time they rebuild and reinforce an embankment it just washes out somewhere else a few months later you would think that they might twig that a cheap standardised viaduct might be a better (i.e. more resilient) repair, even if it costs a bit more in the short term.

If you've seen the photos it looks like it's deliberately sacrificial - you can clearly see a concrete base under the bit that's washed out. Piling up a load of ballast and running a tamper over it doesn't cost that much in the scheme of things. That said, I do wonder if some sort of low viaduct on driven piles would make sense as you say. They used that kind of thing for the S&C landslip.
 

krus_aragon

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They really need to be trialling an alternative: if every time they rebuild and reinforce an embankment it just washes out somewhere else a few months later you would think that they might twig that a cheap standardised viaduct might be a better (i.e. more resilient) repair, even if it costs a bit more in the short term.
That's part of the problem: NR are only funded to maintain the route, and repair any damage it sustains. Preventative maintenance on the bits that haven't been washed out would "come from a different pot of money", so I'm told. (I know, it's crazy!) On the plus side, NR spent a bit of extra planning time during last year's repairs to put together a shovel-ready design that they could keep in a folder ready for the next washout, rather than go back to the design board every time.
 

krus_aragon

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If you've seen the photos it looks like it's deliberately sacrificial - you can clearly see a concrete base under the bit that's washed out. Piling up a load of ballast and running a tamper over it doesn't cost that much in the scheme of things. That said, I do wonder if some sort of low viaduct on driven piles would make sense as you say. They used that kind of thing for the S&C landslip.
Going from memory of the presentations in Llanrwst last year, it's not a concrete base, but some impermeable layer that it meant to stop the bottom ballast from washing away or being mixed up with the upper ballast. The foundations are still there, it just needs some fresh ballast on top, as you said. (Forgive the non-technical terms.)
 

Y Ddraig Coch

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That's part of the problem: NR are only funded to maintain the route, and repair any damage it sustains. Preventative maintenance on the bits that haven't been washed out would "come from a different pot of money", so I'm told. (I know, it's crazy!) On the plus side, NR spent a bit of extra planning time during last year's repairs to put together a shovel-ready design that they could keep in a folder ready for the next washout, rather than go back to the design board every time.

As you can see below. In certain areas that used to flood they have managed to keep the track above the water by digging the sides down ,Sadly that just isn't possible everywhere.
IMG-20200209-WA0039.jpg IMG-20200209-WA0040.jpg
 

Llanigraham

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2 units still stuck at Newtown Station.
I drove back from Welshpool lunch time and don't think I've ever seen so many NR vans parked at access points, with lots of bodies walking the track and obviously inspecting things. The section from Buttington Crossing to Cilcewydd Bridge is like one huge lake.
 
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