It was built from hazel, laid carefully across wet ground to allow passage where passage would otherwise have been impossible. This is a togher, an ancient form of wooden trackway constructed through bog or marsh by splitting, stacking, and laying timber directly onto the soft ground. The Derrylough example runs for 110 metres, orientated roughly east-northeast to west-southwest, and measures just 1.4 metres wide, barely enough for two people to pass one another. It sits at a depth of 0.26 metres, which in bog terms means it has been preserved in conditions of low oxygen and high acidity for potentially thousands of years.

The structure is classified as a class 2 togher, a designation that reflects its construction method. The walking surface consists of hazel roundwood, the straight young stems of hazel cut while still slender, each averaging around six centimetres in diameter. Beneath these lies a substructure of hazel brushwood, the smaller, branching offcuts and trimmings packed together to provide a stable foundation across the yielding bog surface. Hazel was a practical and deliberately chosen material. It coppices readily, meaning it regrows quickly after cutting, and produces long, straight poles well suited to this kind of work. The combination of a brushwood base and a roundwood surface represents a considered piece of engineering, modest in its components but effective across difficult terrain. Work of this kind was carried out by the Irish Archaeological Wetland Unit, based at University College Dublin, which recorded bogland sites across the Irish midlands before drainage, peat extraction, or development could alter or destroy them.