Race against time to lift 80-tonne rail bridge near Machynlleth ends in success
Network Rail have completed a £3.6m, six-week project to lift an 80-tonne bridge near Machynlleth by hand to avoid flooding.
They had a six week window to complete the project as the stretch of river Dulas is a fish spawning river there was a limited period during which the work could be carried out.
The bridge on the Cambrian Line between Machynlleth and Shrewsbury in England, has closed 30 times in the past decade due to flooding. The line reopened on time, today, 28th June 2021.
Engineers opted to lift the 80-tonne bridge manually, rather than using hydraulics, to ensure there was no twisting or buckling of the structure. Eight sets of 20-tonne chain hoists were used in total. For every 10 metres of chain pulled, the bridge was raised just 10mm.
This resulted in more than 12,800 metres (12.8km) of chain being pulled by hand through the lifting blocks.
Richard Compton, project manager for Network Rail Wales and Borders, said: “Black Bridge has repeatedly flooded over the years during periods of heavy rainfall, causing regular closures and long delays for passengers. We experienced this flooding first-hand during our work, which shows exactly why raising the bridge is so important.”
AmcoGiffen was the contractor hired to complete the work. Their regional operations director Andy Crowley said: “With nine months from concept to completion, we knew from the outset that it was going to be challenging to deliver this scheme in such a short timescale.
“We also understood the necessity behind the risk being taken. Collaboration was crucial from the start and when severe weather hit the early days of the project, we all worked together to recoup the lost time and maintain our schedule.”
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If fairness “race against time” is a bit hyperbolic. But “project completed in line with programmed dates” gets fewer clicks
first and last example of levelling up, lol
A feel good story in rural Wales, we need those at the moment; this story has it all, engineering innovation, public transport, environmentalism, economics, all on time and within budget. 😁🏴
Perhaps we need more rail not more road, more trains and fewer cars. I’d love to see a direct rail link from Swansea to Aberystwyth to Bangor.
Does this mean they raised it by 160 millimetres?
That’s what the numbers appear to say, yep (that’s close to 6½” to those who prefer obsolete units). Doesn’t seem like a lot, but as I understand it, gradients on railway lines have to be veeeeery gradual. Probably had to relay ¼km of track on either side to match it in
Would you like to show your workings?
1 metre of chain pulled raises the bridge by 1 millimetre thus if 12,800 metres of chain were pulled how long does it take to fill the bath?
Anybody remember this: https://youtu.be/MXCARVLPLcI ?
How many furlongs in a bushel?
Raised by 1 metre according to the BBC.
Well, on the first fag packet my figure of a 160 mm rise was wrong by a factor of 10, so lets forget that. The question is “how far did they raise the bridge?” since the article is silent on that and I hadn’t seen the BBC report. From the article, the ratio of chain pulled to lift obtained is 1:1000. So pulling 12.8km of chain would lift the bridge 12.8 metres. Obviously unrealistic. Eight hoists are reported, so I assume the 12,800 metres of chain pulled through the lifting blocks was the total for all eight hoists. 12.8 metres… Read more »
Yeah, I got 1.6m too.
Maybe the BBC was using crude rounding, or maybe the bridge was considered to need 0.6m to raise it to levels of past flooding and the extra meter is future-proofing above that level, or maybe I’m reading too much into a bit of rushed copy.
why don’t the just dredge the river would have cost less
A river keeper once showed me a stretch of the Kennet in Berkshire that was dredged to “improve the flow” during the war. He said it didn’t work and had also destroyed the fishing in that section. The point is that dredging to drain flood water off more quickly has to be continued all the way to the sea because, if you don’t, the dredged section fills up immediately and then you’re back to square one. And, according to the report above, the Dulas is a spawning river so it’s not a good idea to bugger up the bed.
Not in the long run.
The bridge is stone, over a hundred years old and a listed structure so if the work keeps it going for another century fair enough. Dredging would have to be repeated and is usually very environmentally damaging, there might also be a problem with rampaging angry anglers waving long poles, their flies open and carrying smelly nets!