Gelli Tunnel at The Black Mountains

Background

Gelli is a short tunnel on the route of the Rhondda and Swansea Bay Railway (R&SBR). I have found many different quoted lengths for this tunnel (160, 164, 167, 169, 174yards) but I believe the most common opinion is that it is 167yards long. The reason for this ambiguity seems to be that the tunnel is often included only as a footnote in detailed accounts of the more famous Rhondda Tunnel, which all sources can agree was 3443yards in length. If I was really concerned, then I’d go back with a tape measure, but I’m not.

Similar confusion exists surrounding the dated on which the tunnel was opened, with estimates ranging from 1882 to 1900. The Rhondda tunnel was opened in 1890 so it is reasonable to assume Gelli was opened in the same year, or soon before. There is no date-stone on the tunnel to eliminate speculation.

By 1880 the demand for coal and coke from the Rhondda Valleys was exceeding the capacity at which the Taff Valley railways and Cardiff docks could export it. Up until this point, proposals for the connection of Swansea docks with the Rhondda Valleys had involved negotiation of the steep, long gradients to Treherbert which required very expensive and large scale construction. Eventually the decision was made to cut through the mountains between Blaengwynfi and Blaencwm (the Rhondda Tunnel) and the collieries at Treherbert were finally connected to the Swansea docks in December 1894. As the Great Western Railway had already laid tracks in the Afan Valley, and naturally along the most favourable route, R&SBR were forced to run tracks alongside over slightly more challenging terrain. At Gelli Farm, just north of Croeserw, it was necessary to cut the short Gelli tunnel through the feet of Mynydd Rhiw-llech to follow this route.

Despite very successful export operations (expansion of Swansea Docks was required in order to cope with the additional coal) R&SBR made very little provision for the commercial aspect of the route, and struggled to survive. In 1907, they were taken over by Great Western, although the line was still operated independently. On new years day 1922 the line was fully incorporated in to the GWR. The line with it’s two tunnels, one very long and the other very short, closed in 1962.

The Tunnel today

Gelli is a very easy tunnel to visit. Loads of parking is available around Gelli cottages, which are only a few yards from the Northern portal. After a few moments while our eyes adjusted to the dark, light could be seen filtering around the curve of the tunnel from the southern end. This is the first tunnel we have visited where our first pass through was made without any lightsources. The northern portal has been neatly lined with brick but after a few dozen yards this gives way to rough-cut stone for the rest of the tunnel. Apart from one collapsed portion of wall, overall condition is good, and it was dry throughout.. There is quite a lot of fly-tipped rubbish in the tunnel; easier to take it down the dump perhaps? People.