Pencaedrain Tunnel / Rhigos Tunnel at The Black Mountains

Background

Despite the fact that this tunnel is quite nearby, I knew nothing of it’s existence until a few days ago. Looking through the excellent Rhondda Cynon Taf library archives, trying to dig up old pictures of the Rhondda valleys I stumbled across this picture. Simply titled Rhigos Tunnel, my curiosity was piqued as I knew of no tunnel at Rhigos. A little detective work revealed that the name of the tunnel was Pencaedrain Tunnel, north of Rhigos and about a mile east of Pontneddfechan. It is 520 yards long and the eastern portal is well and truly buried, under the A465 Heads of the Valleys road. It was owned by the Vale of Neath railway and was built 1n 1851, finally closing in 1967.

Visiting

The best place to start from is the car park at Dinas Rock, east of Pontneddfechan. There are several small roads leading away from this car park, the one to take is the southerly road that climbs steadily up past some recent-looking spoil heaps before turning east and getting suddenly steeper. It’s not a long walk, and soon you will find a wooden fence either side of the road ahead, with a gate. This is someone’s house so don’t go down there, instead turn back on the path that merges from the right. The Heads of the Valleys road should be quite loud from here as it’s very close. This path goes downhill and west, and descends on to the old track bed. After only a few yards, however, you’ll notice a steep cutting on your left; the western portal of the tunnel is here.

Condition today

The approach to this tunnel is quite boggy, and was especially wet on the rainy day we visited, so wellies will be very useful here. Don’t try this in anything less sturdy than walking boots though, unless you’re a ninja or don’t mind getting your feet wet. Once inside, there are a few yards of ankle deep water and silt, that can be most easily avoided on the right hand side, before the going gets easier. A stream runs down the length of the tunnel, with muddy patch here and there all the way along. In my opinion, this tunnel seems to be a lot longer than only 520 yards.

There are very long thin stalactites hanging from the ceiling and lots of short, dumpy stalagmites on the floor that are very hard. Most are pure white with a few rusty coloured ones. The only structural damage to be seen is a very large chunk of rock that seems to have dislodged from the back of a refuge. Nearing the other end the air became drier and the noise of the road died away to nothing and suddenly we found ourselves facing a surge of infill like a tidal wave of earth frozen in time. Close inspection reveals that where the infill slope meets the tunnel walls and roof, the bricks are replaced with large facing stones – the buried portal is right here, at this point. From what I can tell, the infill is from the embankment of the Heads of the Valleys road above.

The most exciting feature of this tunnel (for me anyway) was to be found about halfway along. What we assumed to be a refuge was actually a drift mine of considerable depth. We didn’t go inside as mines can be very dangerous, but we may explore this in the future with the proper equipment.

UPDATE 23.05.2010 – Exploring the mine

A few weeks passed before we got a trip organised to return to Pencaedrain and explore the mine at the tunnels halfway point. Following a morning meeting in the layby on the A465 (which turns out to be closer than Dinas Rock car park) we were ready to go – five of us this time, equipped with hard hats and a gas-tester. The tunnel cutting was as boggy as ever, but we all had wellies now, so no probs. After a brief visit to the far end of the tunnel (and again it seemed much longer than the stated 520yards) we returned to the mine, and started exploring.

The first few yards of the mine were easy going, as it is high enough to stand up in. In the distance we could see a spot of light. The ceiling then became lower, and for half the length of the tunnel we had to stoop to make progress. There was a strong smell of diesel oil, and the water on the floor had oil slicks on the surface, perhaps leeching from coal seams the tunnel passes through. The final third of the tunnel was very difficult to traverse. The ceiling became lower still, and progress was only made on all fours – difficult when carrying a lot of photographic gear and torches. The situation wasn’t helped by a floor covered in razor sharp flakes of rock, delaminated from the ceiling, that cut into unprotected hands and knees. In all the tunnel is about 150yards long.

Eventually warm, moist air with the smell of foliage began to replace the oily, cool atmosphere of the tunnel, and we emerged onto a shelf in the rocky sides of a river gorge, the stream Nant Sychryd flowing far below. After a brief stretch and a rest it was time to brave the tunnel once again.

Everything about this tunnel is strange. It is almost certainly a mine, as it passes through coal seams and a tunnel this short would not have demanded an airshaft. It appears to have been cut from the tunnel outwards, as the large lintel would have been constructed first, and the opening into the river gorge is very difficult to access from outside. But it was not carved away from the back wall of a workman’s refuge, as is seen in other cases where locals have mined coal seams intersected by train tunnels, instead being cut between refuges. It’s original purpose remains a mystery – for now.