Engine Arm Aqueduct, Birmingham Canal Wolverhampton Level

Engine Arm Aqueduct, Birmingham Canal, Wolverhampton Level

An iron trough aqueduct with towpath roving bridge, built around 1828 by Thomas Telford. The aqueduct carries the Engine Arm of the Wolverhampton level canal over the deep cutting of Telford's new Birmingham mainline navigation, ensuring the continued supply of water from the Rotton Park Reservoir.

The aqueduct is orientated north-west to south-east and has a towpath on both its east and west sides. The towpath roving bridge is located at the north-west end, orientated north-east to south-west, and is constructed of blue engineering brick with stone copings and rusticated stone arch details. The bridge was conceived as an integral part of the aqueduct scheme to allow the towpath to cross the entrance to the aqueduct.

The aqueduct is an iron trough supported on a single span, cross-braced to counter the outward thrust of the weight of water carried. It springs from stone and brick abutments. Both the east and west faces are identically designed with decorative ironwork tracery of three orders. The grid-work of the cross-bracing rises from a single span arch with fluted Gothic columns supporting pointed arches and pierced quatrefoil spandrels above. Plain square section railings rise to trefoil arches immediately below a simple rolled handrail. The handrail terminates in short octagonal stone end piers, seven faces of which have recessed oblong panels with decorative blind tracery echoing the trefoil arches of the railings. Sloping octagonal stone copings cap the piers.

The abutments are constructed in engineering brick in English bond with deep rusticated stone coins and copings. The towpath has a brick surface with raised footholds. The humpbacked towpath roving bridge is constructed of blue engineering brick in English bond with a flattened elliptical arch and vermiculated rustication to the stone quoins. Sloping abutments set at 90° to the bridge, on its south side, carry the towpath from the level of the aqueduct over the bridge and have plain curved stone copings.

The Engine Arm Aqueduct is an unaltered example of a nineteenth-century iron trough aqueduct and canal roving bridge surviving intact with elegant Gothic design details. It demonstrates Telford's technical innovation in using the iron trough method, which allowed aqueducts to securely straddle a far greater width than traditional masonry methods. The broad span latticework arch demonstrates Telford's development of engineering techniques later taken further in his suspension bridges and road bridges. The aqueduct has strong group value with Telford's improvement scheme to the Birmingham mainline canal.