Report - - Walnut Tree (Garth) Tunnel, South Wales - January 2014 | Underground Sites | 28DaysLater.co.uk

Report - Walnut Tree (Garth) Tunnel, South Wales - January 2014


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Visited with lenston147.


The Barry Railway Company was developed to transport South Wales' coal into Barry Docks, breaking the monopoly of the Taff Vale Railway and Cardiff Docks. Work on its network started in 1885 and encompassed 68 route miles by the early 1900s.

One of the later additions was the Rhymney branch, driven northwards from Tynycaeau Junction to Penrhos Junction. Opened in 1901, this featured two significant structures. Walnut Tree Viaduct involved seven lattice girder spans supported by brick piers, 516 yards in length and 120 feet high. This was demolished between 1969-74. Not far from its southern abutment was a tunnel of the same name, occasionally known as Garth.

A footbridge crosses the southern approach cutting just in front of the portal which is stone-built with buttresses either side of the entrance. 490 yards in length, the tunnel's lining comprises vertical masonry side walls and a segmental arch in brick. Refuges are provided, many with exposed rock at their rear. Though straight at the southern end, the bore curves westwards as daylight returns at the north end. The portal there is of a similar design to its sibling.

Traffic over this section of line ceased on 31st March 1963 following a blaze which destroyed Tynycaeau North signal box. The route was officially closed that summer.

Now gated at both ends, the tunnel has been breached by quarrying, creating a 50-yard air gap close to its centre. The remainder is generally dry and free from clutter.

(Courtesy of Graeme @ Forgotten Relics)


Walnut Tree tunnel would not in any way be considered one of the 'great' South Wales tunnels. It isn't (or wasn't) that long at 490 yards, it wasn't designed or built by Brunel and it wasn't even on the powerhouse Taff Vale Railway line (it was a Barry Railway Company tunnel). But it is probably the most unique in that the interior must be the least documented in South Wales.

This is due in the main to Cemex who run a very large and very active limestone quarry a few yards to the west of the tunnel. And quite a quarry it is -


(Photo Geology Wales)

Access to Cemex Taffs Well Quarry used to be located at the extreme western end of the quarry until Cemex built a new access tunnel to the quarry at the eastern side which is less than a mile from the main A470 dual carriageway. The new access tunnel -


(Photo Geology Wales)

To actually construct this new access tunnel involved the not insignificant procedure of breaching Walnut Tree tunnel about 260 yards from its northern portal. The breach removed approx. 50-60 yards of the original railway tunnel. This photo again shows the new road access tunnel and also, at approx. three o'clock, the continuation southwards of the railway tunnel -


(Photo Geology Wales)

As a consequence, Walnut Tree tunnel has always been well secured as it effectively now brings you straight into the quarry and its north of £50m equipment. We had been looking around the area the previous week but after a 20+ stone Gloucester rugby supporter had barrelled into my back the previous day, I wasn't in any state to get into the tunnel. We also noticed a shed load of lids all over the place so fast forward a week with back super glued together and drain keys in the bag instead of the car boot, we returned.

1. Northern portal

2. The view southwards

3. View back to the portal

4. One of the few non wrecked refuges

5. Patch

6. Approaching the breach

7. Quarry below

8. Back

Unfortunatly, belting across the quarry to the southern section (approx. 120 yards) of the tunnel wasn't an option as the quarry wasn't empty and whatever they were doing just below us, they were making one hell of a racket. lenston does have a photo of the southern portal from the previous week so hopefully will post it up.

And all that is left today -


Thanks for looking !