Turn off the Heads of the Valleys road at Clydach. Pass the campsite, picnic site and Ironworks on the right. Turn right along Quarry Road and pass the village hall. Keep left at Dan-y-coed and continue approximately half a mile to park at small layby with old limekilns on the left or at off-road parking area just around the corner on the left. (SO221125)
The route follows part of the former Merthyr, Tredegar and Abergavenny Railway which itself started its existence in 1794 as the Clydach Rail Road tramway carrying raw materials to and products from the iron works of the Tredegar Iron Company. The railway included a number of steep inclines with gradients as steep as 1 in 34, making it more expensive to run than other local tracks; and it was closed in January 1958.
Some of the tunnels that this railway route used are currently blocked so an alternative cycle route has been created using the old tram road that the railway replaced in 1864.
There are some splendid old mining and quarrying ruins along the route, including a magnificent viaduct at Clydach and spectacular views over the Brecon Beacons National Park and Blaenavon World Heritage site.