Set seven metres south of the main span, this so-called dry arch, just 2.2 metres wide and 1.3 metres high, exists purely to carry the approach road across the waterlogged floodplain at the southern end. It has been infilled with masonry on its western side and is now largely invisible beneath dense ivy, which also smothers the southernmost arch of the main bridge. That detail, easy to miss from a passing car, says something about how old infrastructure quietly accumulates layers of repair and concealment. The bridge also sits precisely on the boundary between two townlands, Monaster North and Monaster South, with the river itself drawing the line between them.

The structure dates to around 1750 according to the National Inventory of Architectural Heritage, though it may contain earlier fabric. It was already old enough by 1840 to be recorded simply as a five-arch bridge in the Ordnance Survey Name Books, and it appears on the seventeenth-century Down Survey map under the name River Comoge, and again in the 1655 to 1658 Civil Survey of Limerick, which traces a highway eastward from the bridge toward the lands of Rathmore. The antiquarian Thomas Westropp, writing in the early twentieth century, called it the Abbey Bridge, noting its proximity to Monaster Abbey some 200 metres to the southeast. Westropp also recorded a local tradition that the crossing occupies the site of a much older ford, known as the Ford of the Chariots of Fergus, a name that suggests a place of some significance in early Irish geography or legend. Thirty-seven metres upstream, an eel weir still sits in the river, a reminder that the Camoge was once worked as well as crossed.

The bridge is 22 metres long and 5.2 metres wide, built of roughly hewn limestone with dressed voussoirs, the wedge-shaped stones that form the curve of each arch. The pier bases have been reinforced with concrete above the waterline to protect against scour, the gradual erosion caused by river flow, and the upstream face carries pointed cutwaters in both the original cut limestone and the later concrete casing. The approach road makes a slight turn where the bridge stones merge into a field boundary wall, a detail worth noticing on foot. The river here was last dredged in 1978. The surrounding land is low-lying pasture, and the southern approach in wet conditions can be uneven underfoot, which is precisely what the dry arch was built to address.