A togher, as these ancient bog roads are known, is essentially a constructed trackway laid across wet or unstable ground, allowing people and animals to cross terrain that would otherwise swallow them. The one at Longfordpass is no modest affair: it stretches for 525 metres, running northwest to southeast along the narrowest section of the bog, and lies broadly parallel to the modern road beside it, the ancient and contemporary routes following the same logic of the landscape across three thousand years.

A peatland survey carried out in 2006 by Archaeological Development Services identified the trackway at 30 separate sightings across the bog, both on the field surface and in the cut faces of drainage channels. Dated to after 986 BC, it was built from oak planks laid transversely across the route, secured in places by wooden pegs and stabilised by longitudinal roundwood runners running along its length. In many sections an underlying bed of sand and gravel had been laid first, and the same material appeared between and occasionally over the structural timbers, suggesting deliberate preparation of the ground beneath. The width varies considerably, between 1.2 and 5.3 metres, and preservation is uneven: where the peat has protected the wood it survives reasonably well, but at the eastern end, where industrial milling has removed much of the peat cover, only the lower portions of the structure remain. One documented section at the southwestern end consisted of a single transverse oak plank, 1.18 metres long and 0.08 metres deep, held in place by a peg at each end and sealed beneath a patch of sandy gravel. Perhaps the most intriguing detail is that bog butter, the ancient practice of burying dairy fat in peat for preservation or ritual purposes, was recovered to the northeast of the trackway at a comparable depth in the bog. The surveyors noted that this proximity, and the shared stratigraphic level, suggest the butter and the road belong to roughly the same period, placing both squarely in the early Iron Age or late Bronze Age.