Tidal Surge Barrier, River Hull

Tidal Surge Barrier, River Hull

A tidal surge barrier and standby generator house built between 1977 and 1980 for the Yorkshire Water Authority. The barrier was designed by Shankland Cox Associates, with Oliver Cox as partner-in-charge, and consulting engineers Sir M MacDonald & Partners.

The barrier straddles the River Hull close to its confluence with the Humber estuary. It consists of two triangular concrete towers, one on each bank, linked by a high-level enclosed walkway with a triangular section. The towers are constructed of board-marked concrete with regular horizontal joints and recess joints at 4.2-metre intervals. The finish is cast using white Portland cement and crushed Ballidon limestone for fine aggregate, with well-weathered Douglas fir boards used for the shuttering. Deep counterweight wells run vertically through the centres of both towers, extending 3 metres below the river bed, with concrete foundations almost as deep below ground as the towers are above ground.

The barrier's principal operating mechanism consists of a 212-tonne vertical lifting gate set between the two towers. When raised, the gate tilts 90 degrees from vertical to horizontal to maximise clearance, providing a clear opening 30 metres wide with vertical clearance of 22.6 metres above normal water level. When closed, the gate seals on a sill built into the river bed. Two 22-tonne chains on each side connect to the gate, pass over drive and idler sprockets, and are then connected to 55-tonne cast-iron counterweights which run up the centre of each tower. Five subsidiary sluices in the main gate allow water to flow from the River Hull into the Humber as the tidal level falls, preventing a build-up should the gate be damaged or otherwise prevented from being lifted. The barrier can be operated in several ways: day-to-day operation uses a hydraulic system, but in an emergency it can be lowered without power.

The barrier's primary function is to prevent dangerously high water levels in the Humber estuary from entering the River Hull and threatening to flood more than 17,000 properties. It is located close to the confluence of the River Hull with the Humber.

Towards the top of each tower leg is a small square room projecting out from the angled inner wall faces. Curved concrete guide beams project out beyond these rooms on the south side. The west tower's room houses the control room and has large windows on its north and south sides; the east tower's room has much smaller, two-pane windows. Both rooms have triangular sloping glazed roofs.

On the outside face of each tower is a fully glazed triangular staircase well with chamfered top and bottom, resting on a triangular concrete pier. Adjacent to the piers are entrance doorways with solid timber doors. The west tower has a bronze opening plaque inset in the pier. The high-level triangular walkway is fully glazed using full-height vertical rectangular panes with slender metal mullions.

The green-painted barrier comprises four main steel beams bolted to connecting diaphragms with wheel boxes to the outer edges, covered in bolted steel skin plate with skin plate stiffeners to the north face (uppermost when raised and horizontal), and incorporating five subsidiary sluice gates. Green-painted steel gate guides are attached to the inside of the concrete guide beams.

Internally, the triangular staircase wells contain staircases wrapped round small lifts. At ground floor level is a small steel spiral staircase with textured steel treads set to one side of a small lift in a wire cage. Above this, the staircase is a larger triangular structure filling the staircase well and enclosing the lift, with angled flights of textured steel treads fixed in hollow-section steel framework with circular steel tube railings and landings to the inner tower side. The counterweight wells in the towers are separated from the staircase wells by concrete walls with large circular viewing apertures at each staircase landing. The control room contains an updated control panel. The machinery rooms contain replacement motors, gearbox, spur gears and counterweight chains. The walkway has an internal triangular frame of steel circular sections with horizontal I-section rolled steel joists.

Adjacent to the west tower is a small, approximately L-shaped single-storey standby generator building constructed of board-marked concrete treated similarly to the towers. The ground level on the south side is higher with a rising flight of progressively wider concrete blocks against the building, incorporating a flight of steps at the left-hand end rising to the flat roof. The steps have circular-section handrails which continue round the edge of the roof, forming a viewing platform. The west side has a deep chamfered brick plinth along its length wrapping round the outer corners. At the left-hand end is a second flight of concrete steps to the roof set into the plinth. On the roof is a tall curved steel funnel venting the generator house. The lower ground level on the east and north sides has an entrance doorway with solid timber door, a horizontal three-light window with timber frames, and large louvred apertures for the generator room. The interior walls are either painted board-marked concrete or plastered, with orange-brown rectangular tiles to corridor floors and solid timber doors to rooms, which include a generator room, staff room, stores and WCs.

The special architectural interest is concentrated in the structural form of the buildings rather than the operating plant contained within. The updated control panel, replacement motors, gearbox, spur gears and counterweight chains are declared not to be of special architectural or historic interest.