The layout is freelance representing a typical Welsh slate carrying railway, built to carry the slate from the quarries to the exchange sidings.

The main locosheds and exchange sidings are located at Talybont Station. From here the line climbs up the valley, through the passing loop at Trem Yr Aifft, where there is a branch to some small quarries. From here the line continues up the valley crosses the river and enters Llanbryneglwys.

This is the limit of passenger working, but the line continues on to the quarries.