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Saturday, 25 February 2017

Eden Brows - the Underground Viaduct

For the past year and more I have Blogged (horrible word) about the enormous landslip at Eden Brows, near Carlisle, which severed the Settle-Carlisle line to through traffic.

On March 31st the line re-opens after 15 months of closure.   By then the tracks will be reinstated and back in use, amid great celebration including an inaugural steam train hauled by Flying Scotsman.

But what will passengers SEE at Eden Brows?   Almost nothing out of the ordinary is the answer which is something of an anticlimax.    That seems an awful shame after all that effort in dealing with the biggest landslip ever tackled by Network Rail.

The repair has involved constructing what amounts to a brand new viaduct to add to the 22 which already exist along the line but it is entirely underground, beneath the tracks so totally invisible.   If anything is to be made of this in public relations terms it would be good to find an existing viaduct of comparable size to that underneath Eden Brows.    Yesterday I discussed this with Network Rail's Eden Brows scheme manager Phil Middleton who was able to give me the measurements.

In 'old money' Eden Brows viaduct is 79 feet deep and 82 yards long.   Four of the existing s&C viaducts are of similar size.   These are

Ais Gill Viaduct - 75ft tall x 87 yards long - almost identical but it crosses a steep ravine so the height is mainly in the middle.   Even so, it is impressive:

click to enlarge

That centre pillar is not quite as tall as Eden brows is deep.

High Stand Gill Viaduct is 60ft high by 91 yards long but trees obscure much of it.

Crowdundle Viaduct is just 55ft tall by 86 yards long so the height does not do justice to Eden Brows:

Finally, there is Dry Beck Viaduct which at 80 feet tall by 139 yards long could suit the purpose nicely:

click to enlarge

The height above ground is just about spot on.   Although it is longer than Eden Brows, the far ends are obscured by trees, leaving the visible arches to represent the scale of the Eden Brows below-ground works almost exactly.   What is more, it is very near to Eden Brows so providing an almost on-the-spot comparison.

In summary, the first and last of the above pictures represent the enormity of the Eden Brows underground viaduct.

In passing, here is a cross section of the part of Eden Brows Viaduct that is presently under construction - the decking slab in yellow and the railway itself:

Note how the tracks are on an angle.   The viaduct is on a curve and the trains when at full speed need to lean into the curve.

Altogether mighty impressive I reckon

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