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Report - Gyfylchi (Tonmawr) Tunnel, South Wales - November 2012

Discussion in 'Underground Sites' started by cunningcorgi, Dec 16, 2012.

  1. cunningcorgi

    cunningcorgi 28DL Regular User
    Regular User

    Apr 12, 2011
    Likes Received:
    Visited with wonkycows.


    Built to accommodate broad gauge trains, the South Wales Mineral Railway served the colliery of the Glyncorrwg Coal Company. Authorised in 1853, the section between Briton Ferry and Tonmawr opened on 1st September 1861 with an extension to Glyncorrwyg coming on line on 10th March 1863. A standard gauge conversion occurred in May 1872.

    The route from Tonmawr cut through the hill towards Cymmer via a single bore tunnel measuring 1,109 yards. Though largely unlined, its roof boasts an irregular brick arch throughout and repair collars have been installed over the years in areas of weakness. Originally contracted to cut it was J G McKenzie and Berwick-born engineer John Dickson but his contract was re-let after three years due to a lack of progress.

    Death attended on 16th August 1902. Trains traversing the route in opposite directions had two opportunities to pass - at Tonmawr and Cymmer, either end of the tunnel - although the former was only rarely used. However, on this day, the colliery company's cashier was in a hurry to get to Britton Ferry so asked the Traffic and Telegraph Clerk at Glyncorrwyg if his train, travelling in the Up direction, could pass the Down service at Tonmawr, so speeding his journey. With the driver thus instructed, the train departed.

    The Clerk wired Cymmer to say that the train had set off but no reply came. He then wired Incline Top - an outpost some distance beyond the tunnel - to discover the location of the Down engine. It had already left. He wired again, asking them to call Tonmawr and arrange for the train to be stopped there. But the signalman had left his post early.

    A collision was inevitable, the coming together occuring close to the tunnel's centre. Climbing a 1:70 gradient, driver Hughes saw the Up train approaching and brought his Down engine to a stop just as it was struck.

    Although the line only officially carried minerals, passengers were often accommodated in the guard's van. On this occasion, seven were on board - all sustained serious injuries, two lost their lives. The cashier, riding on the footplate, was also injured together with both drivers and firemen.

    The end of the line came on 13th July 1947 when a landslip blocked the approach cutting at the tunnel's western portal. Since its abandonment, this end of the bore has become flooded, with the waters first making their presence felt close to the centre. Given the gradient, it's likely that the tunnel is drowned to its roof for about 100 yards.


    A very dark tunnel in more ways than one - as one end is blocked by a landslide and the other is breeze blocked with the cutting also blocked with dumped trees, very little air goes through and soot from loco's over the years remains in situ. Also, some visitors have described an uneasy feeling while walking the tunnel and put in down to drug taking that appeared to have taken place here (plenty of bongs, solvents, etc. still scattered around from years ago but why someone would want to troop miles into a forest to partake beats the shit out of me) or the fact that two people died in here as described above.

    As it was, we were happy enough to get in as it was pissing rain outside.

    1. Southern portal (it is in there somewhere through all the crap).

    2. Inside the southern portal

    3. Mist looms ahead

    4. Yogurt bong

    5. Lonesome marker post

    6. Brick roof, rock walls

    7. Strengthening collar

    8. Brick repair work

    9. End of the line

    Thanks for looking.

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    #1 cunningcorgi, Dec 16, 2012
    Last edited: Dec 16, 2012

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