Built 1815 by a company named 'The Brinore Tram Road' to take coal, lime and iron (from Union Ironworks near Rhymney) to the Brecknock and Abergavenny Canal at Talybont. The engineer was George Overton. The route around Blaen Dyffryn Crawnon was always known as the most precipitous part of the route, where the tramroad could be made only by cutting a ledge into the steep slope. The tramroad closed c1890 after a lengthy period of decline, especially after the Merthyr & Brecon Railway opened in 1866.

In the section at Blaen Dyffryn Crawnon the tramroad has a gentle gradient, artificially cut into ground, which follows upper edge of scarp; the downhill N side bounds modern forestry. In the form of a hardcore track, no original setts or features visible. Rock-cut ledges up to 20m high were quarried out during construction: At SO0998415123 is a ledge 25m long and up to 4m high. A ledge 10m long and 6m high is at SO0995415102. At SO091815021 ledge is 2m wide with battered dry stone walls. Tramroad is cut into rock, on up- and downhill sides, at SO0953314929. Stone revetment wall to uphill side at SO0941815005. To N of here, tramroad is eroded away, just downstream from a waterfall. Adjacent to limekiln (NPRN293100), rock-cut cliff is 20m high, with further steep drop on downhill side.
Recorded as part of Uplands Initiative Survey. The tramroad follows the N boundary of the Eastern half of the survey area. W B Horton, H&H, 3/11/2006.