Design and Engineering

Mellows Bridge, a masonry three span arch of 43m, was built from 1764-1768 to a design of Colonel Charles Vallancey. The foundations of the piers were designed to be laid in caissons and, according to surviving drawings, without piles. This, it must be remembered, is only ten years after George Semple had introduced the construction of cofferdams for building piers to Ireland with the construction of Grattan Bridge. The caissons in this case were probably timber walled structures, the bottom of which did not necessarily rest against the rock, but on any hard or compacted stratum encountered. Timber centering would have been used in the erection of the arches, as is the common practice in masonry bridges. The haunching extends to the quarter points of the arches, while the haunching at the abutments is placed in the form of an arch on plan giving further assistance to the abutment to resist the horizontal thrust of an arch structure. The haunching is of quarry stone construction while the fill is a clay material.

The masonry is evenly coursed granite ashlar, rusticated on the archrings and piers. The archrings comprise a series of large vermiculated voussoirs alternating with smaller, smoothly rusticated voussoirs, each decorated with a roll-moulding on their upper edges. The piers are triangular in plan. The masonry of each one is smoothly rusticated and crowned with a single large capstone which functions as a cutwater. Directly above each cutwater there is a round-headed niche constructed of large, well-cut ashlar blocks. The parapet comprises a series of coping stones, curvilinear in section, capping nine sections of cast-iron balusters, alternating with ten dadoes. Beneath the balustrade there are two ashlar masonry courses, the bottom one serving as a plinth. The overall height of the parapet at the rise of the bridge from top to base is 1.61m. There are two large dadoes on the east and west sides of the bridge. Those at the rise of the bridge (one on each side) bear brass commemorative plaques, which both read as follows: “The name of this bridge has been changed to Mellows Bridge to honour the memory of Lieut-General Liam Mellows, Irish Republican Army, who gave his life for the Republic of Ireland, 8th December 1922. Erected by the National Graves Association”. Unlike Father Mathew Bridge and O’Donovan Rossa Bridge, Mellows Bridge has no piers or abutments adjoining the quay wall. However the internal face of the quay wall on all sides slopes outwards towards the bridge acting as a buttress.