The bridge has a clearance of above the high-water mark allowing sailing ships to pass beneath. The height was stipulated by the Admiralty which had insisted on a clearance of at least 75 feet. The approaches to the bridge on both sides accommodated its considerable height and a gradient of 1 in 114 was needed to obtain the necessary clearance beneath the central spans. On the north side of the river, the bridge is approached by a 49-arch viaduct and a short embankment followed by 16 arches. From the south, it is approached by a 33-arch viaduct. The viaduct piers, bridge abutments and the bridge's central piers are of sandstone and the viaduct arches are of brick.