The line runs along part of the trackbed of the northern section of the former 4 ft 8+1⁄2 in (1,435 mm) standard gauge Brecon and Merthyr Railway from Pant to a new station at Torpantau, via Pontsticill and Dolygaer, a total of about 4.5 miles (7 km).

This takes the BMR just short of the southern entrance to the 667 yd (610 m) long Torpantau tunnel, the highest railway tunnel in Great Britain,[3] which carried the original line through the hills along the side of Glyn Collwn to Brecon or to Moat Lane or Hereford via junctions at Talyllyn and Three Cocks.

One of the benefits of the line, and a condition of the planning permission, is that tourists can access and experience part of the Brecon Beacons National Park without driving their cars through it.

At Pontsticill the station house was renovated, the old waiting room was converted into a small workshop and a storage shed was built.

These provide passenger facilities including toilets, cafe, shop and booking office as well as the extensive workshop used to build and maintain the railway locomotives, carriages and wagons.