Just beyond that crossing point, a grassed-over track about five and a half metres wide survives for roughly 250 to 300 metres, hemmed in by earth-and-stone field fences and flanked by coniferous forestry. This is a fragment of the Red Earl's Road, known locally through this particular stretch as the Yellow Pass, a name that carries its own quiet history. The gradient here was so severe that the pass was recorded as not practicable for horses, which tells you something about what it must have been like to move an army along it.

The road is attributed to Richard de Burgh, the Red Earl of Ulster, who acquired Connacht following the Norman expansion into the west of Ireland. The route he is said to have engineered covered approximately 21 kilometres, linking his castle at Ballymote in County Sligo with Boyle Abbey in County Roscommon, running around the northern and eastern flanks of the Bricklieve Mountains. In Irish the road is known as Bothar an Iarla Ruaid, the Road of the Red Earl. Its medieval origin is probable though not precisely dateable. What is more precisely documented are the difficulties it posed to later military users. In 1540, Manus O'Donnell, camped on the Curlew Mountains, set his forces to work levelling off the Yellow Pass to make it passable. A century and a half later, in 1691, when Lord Granard was advancing on Sligo, the horses could not haul the cannon up the gradient and the soldiers themselves were put into harness to drag them.

The section through Ballaghboy runs to around 3.2 kilometres in total, though much of it has disappeared into pasture or forestry. The surviving track is soft underfoot in places and the southernmost portion is entirely impassable under trees. The stretch worth seeking out lies just south of where the N4, the main Sligo to Boyle road, crosses the old line, where the track emerges briefly into legibility before the forestry closes over it again.