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Canal shuts Edinburgh to Glasgow main line

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The severe weather on the night of 11/12 August, that led to the tragic derailment outside Stonehaven, also caused far greater infrastructure damage on the Edinburgh to Glasgow main line between Polmont and Linlithgow. This also had the potential for derailment

However, in this case, there was nothing that Network Rail could have done to prevent the damage, which was caused by massive flooding from the adjacent Union Canal. Due to the amount of rain that had fallen, the canal overflowed its banks, opening up a 30 metre-breach of the canal embankment and allowing a huge volume of water to flood the surrounding area.

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Seen from point 1 on the map looking eastwards, the line appears undamaged apart from some debris. (copyright David Shirres)

The Union Canal, which opened in 1822, is a 32-mile long contour canal between Edinburgh and Falkirk and thus has no locks to stop the flow of water along it. The breach occurred early in the morning. Realtime trains shows that the 05:03 Edinburgh to Glasgow train was the only one to run on the line on the 12 August, thereafter, all trains were cancelled.

By late morning, Scottish Canals placed stop-planks in position to reduce the flow. The planks at Linlithgow were six kilometres from the breach and the water level of the canal there had already fallen by about half a metre.

The railway is in a shallow cutting about 300 metres from the canal breech and is about 10 metres below the level of the canal. At this point, it has a slight falling gradient towards the east.

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Although there appears to be little damage at the point where water poured into the cutting (1), the contamination will require more than a kilometre of track and ballast to be replaced. However, at the eastern end of the cutting (2), the track formation has been extensively washed away under both tracks, the north side of the cutting has been eroded and there is damage to overhead line equipment as masts have had their foundations washed away.

Network Rail advise that it could take two months to reinstate the line though engineers are continuing to investigate the extent of the damage before they can provide a final estimate for restoring service.

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At point 2, looking westwards, there is severe damage to both the track and the overhead electrification structures where the water left the cutting to drain onto the fields below. (copyright David Shirres)

Editor’s thumbnail calculation:

To give a rough indication of the flooding, if the canal is considered to be 3.5 metres wide with an average depth of a metre and half the water over, say a 10 kilometres length escaped, this is equivalent to: 3.5 x 1 x 10,000 / 2 = 17,500 cubic metres or 17,500 tonnes of water which is the equivalent of 7 Olympic Swimming pools being emptied on this one spot adjacent to the railway.

Severe flooding at Polmont, caused by the escaped canal water, closed the line.
Water escaping from the canal (posted by Maike Harvey on Twitter)