Road Bridge over railway

Railway overbridge, 1842-1843

MATERIALS: Sandstone ashlar abutments, piers, arch barrels and parapets; spandrels of squared sandstone blocks laid in horizontal courses.

PLAN: skew arched bridge, between abutments that rise out of the railway cutting’s sides, and crosses the railway at an angle.

DESCRIPTION: this arch bridge comprises three segmental arches. The voussoirs in the arch rings rise from skewback stones above rectangular impost bands, and are stepped to key into the spandrels and help counteract the stresses inherent in a skew bridge. The voussoirs and intrados of each arch are laid according to the helicoidal method where the bedding joints between the stones are at right angles to the bridge elevations rather than to the faces of the abutments. The parapets, which are three ashlar courses high, are distinguished from the spandrels by a horizontal string course at the level of the road deck and surmounted by flat coping stones which, on the elevations of the bridge only, rise from a concave moulding to oversail the parapet walling. Each coping stone is secured to its neighbour by an iron cramp. The first course of parapet walling also breaks forward slightly on the inner face. The western parapet curves out as a short wing wall at either end of the bridge; the eastern parapet is straight.