Summary
Tidal surge barrier and standby generator house. 1977-1980 for the Yorkshire Water Authority, designed by Shankland Cox Associates, with Oliver Cox as partner-in-charge, and consulting engineers Sir M MacDonald & Partners.
Reasons for Designation
The Hull Tidal Surge Barrier and associated standby generator house of 1977 to 1980 for the Yorkshire Water Authority, designed by Shankland Cox Associates and consulting engineers Sir M MacDonald & Partners, is listed at Grade II for the following principal reasons:
ARCHITECTURAL INTEREST:
* Design Quality: the barrier successfully combines functional engineering with aesthetic quality in a slender and dramatically sculptural arch of angular planes;
* Materials: the craftsmanship of the structure is clearly demonstrated in the careful attention paid to good use of materials in the crisply board-marked and jointed shuttering of the concrete towers and grid-like, curtain wall glazing of the stairwells;
* Architects and Engineers: the partner-in-charge was Oliver Cox, a well-respected post-war architect, who worked closely with the notable civil engineering firm Sir M MacDonald & Partners to ensure that the machinery could be accommodated without destroying the geometric form of the barrier;
* Structure: the raised monolithic barrier gate is unusually turned through 90 degrees to a horizontal position, allowing sufficient room for the navigation of larger shipping whilst limiting the overall height of the barrier to prevent it unduly dominating nearby historic buildings, most notably Holy Trinity Church;
HISTORIC INTEREST:
* Location: standing at the confluence of the River Hull and the Humber estuary, the barrier was engineered to protect the low-lying City from the severe tidal surges it periodically experienced, most recently in 1969, when the highest recorded water level to date was reached in the Humber, resulting in heavy flooding of many hundreds of properties.
History
On 29 September 1969 a tidal surge peaked 1.2m above the predicted tide level causing severe flooding in Hull. The city is vulnerable to tidal flooding since 90 per cent of the city lies around 2m below the level of the highest recorded tides in the River Hull and Humber estuary. In 1971 the Yorkshire River Authority (YRA) prepared a preliminary report which examined in detail the case for constructing a tidal surge barrier. It placed a Bill before Parliament in 1973 which received Royal Assent to become the Hull Tidal Surge Barrier Act, empowering ‘the Yorkshire River Authority to construct and operate a barrier, with a movable gate, across the River Hull in the City and County of Kingston upon Hull’.
In December 1973, the YRA appointed Sir M MacDonald & Partners as consulting engineers and the Shankland Cox Associates as architects with Oliver Cox the partner-in-charge. The need for an engineer and architect to work together was appreciated from the outset because the eventual structure would stand in a commanding position in a part of the city where redevelopment was under way and adjacent to a new swing bridge carrying the south orbital road over the river. It was seen as important that the design acknowledged the symbolic meaning as guardian of the City while also being seen as a piece of honest engineering and another working structure beside the cranes and docks. Two options were looked at, a swing boom with flap gates and a vertical lifting gate. The swing boom had a low profile and no bulky superstructure, but was costly, restricted use of the river, and would require a multiple operation to close, making it less reliable. The vertical lifting gate was chosen for its ability to be operated with minimum interference to shipping, the reliability of operation, and because it would cost less to build. An unusual turnover gate was suggested to reduce the overall height of the structure; there were planning restrictions on the height of development with regard to nearby Holy Trinity Church and it was considered that this should also apply to the barrier. However, it was also envisaged that the barrier could be a dramatic structure which could be read as a water gateway, articulating an entry point to the City, and, given the correct architectural treatment, that this would be an acceptable addition to the Hull waterfront.
The resulting design had a high superstructure taking the form of two towers which were designed to support the dead load of the gate when opened and containing the motor rooms, counterweights and lifting gear. A control room was located near the top of the west tower with an extensive view of approaching ships in the River Hull and the Humber estuary. The two towers were linked by a glazed walkway passing over the raised gate. A separate building adjacent to the west tower housed a standby generator to supply electricity for lighting and for the gate operating motors in the event of a mains power failure.
Before construction began, the wind loading of the structure was tested by the Building Research Establishment, Garston, using a 1:200 scale model in their wind tunnel. The towers were then designed as concrete tubes or monoliths to produce very rigid structures with the density of the walls providing the damping required to minimise the oscillatory effect of the wind loads. The profile of the river sill was also model tested in the Hydraulics Laboratory of the Department of Engineering, Cambridge University to establish a profile which would provide the least underwater obstruction to a dragging ship’s anchor and also ensure the minimum scour of the river bed during the operation of the gate. During construction cofferdams were built for the towers using 34m long steel sheet piles, at the time the longest ever rolled by the British Steel Corporation.
The contract was awarded in November 1976 to W A Dawson Ltd with Newton Chambers Engineering Ltd, Sheffield, as the subcontractors for the barrier gate. Work commenced on 17 January 1977 and the barrier was completed in 1980. It was opened on 15 April 1980 by Dennis Matthews, Chairman of the Yorkshire Water Authority, which had superseded the Yorkshire Rivers Authority in April 1974.
In 1981 the Structural Steel Design Awards commended Newton Chambers Engineering Ltd for the high standard of design achieved in the fabrication of the steel gate.
In 2009 to 2010 the Environment Agency undertook a £10 million refurbishment project, which included the installation of a new drive mechanism to raise and lower the barrier gate, with a synchronisation shaft running through the walkway to improve efficiency, and the replacement of the walkway glazing mullions.
Details
Tidal surge barrier and standby generator house. 1977-1980 for the Yorkshire Water Authority, designed by Shankland Cox Associates, with Oliver Cox as partner-in-charge, and consulting engineers Sir M MacDonald & Partners.
MATERIALS: reinforced concrete towers, concrete sill, steel gate and barrier structure.
PLAN: two triangular towers with triangular staircase wells to the outer sides, forming a diamond-shaped plan, standing on either bank of the River Hull and linked by a high level, enclosed walkway with a triangular section. The towers contain machinery rooms at the top, linked by the walkway, with a control room immediately below in the west tower, and counterweight wells beneath running down through the towers and deep into the ground. The triangular staircase wells have staircases wrapped round small lifts. The raised, rectangular gate is stored horizontally beneath the walkway. The closed gate stands vertically between the towers, blocking the river. Adjacent to the west tower is a small, approximately L-shaped, single-storey standby generator building.
PROCESS: the barrier can be lowered when high tidal surges are forecast in order 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 has a 212-tonne vertical lifting gate set between two concrete towers housing operating machinery. When raised, the gate tilts 90 degrees from vertical to horizontal to maximise clearance, giving a clear opening 30m wide with a vertical clearance of 22.6m above normal water level. When closed, the gate seals on a sill built into the river bed. It can be operated in several different ways; day-to-day operation uses a new hydraulic system, but in an emergency the barrier can be lowered without power. Two 22-tonne chains on each side connect to the gate, pass over a drive and idler sprockets, and are then connected to 55-tonne cast-iron counterweights which run up the centre of each tower. The counterweight wells extend 3m below the river bed with concrete foundations almost as deep below ground as the towers are above ground. 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 in the level of the River Hull should the gate suffer damage when in its lowered position or be otherwise prevented from being lifted.
EXTERIOR: the tidal surge barrier is located on the River Hull, close to its confluence with the Humber estuary. The structure straddles the river with a tower on each bank linked by a high level, glazed walkway. The towers are built of concrete and the glazing uses vertical rectangular panes with slender, metal glazing bars.
The main tower structures are triangular and constructed of board-marked concrete with regular horizontal joints and feature recess joints at 4.2m 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. Towards the top of each leg is a small, square room which projects out from the angled, inner wall faces; curved, concrete guide beams project out beyond the rooms on the south side. Both rooms have triangular, sloping, glazed roofs. That in the west tower houses the control room and has large windows on its north and south sides; the room in the east tower has much smaller, two-pane windows. 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. The west tower has a bronze opening plaque inset in the pier. Adjacent to the piers are entrance doorways with solid timber doors. The high level, triangular walkway is fully glazed using full height vertical rectangular panes with slender, metal mullions. The green-painted barrier has four main steel beams bolted to connecting diaphragms with wheel boxes to the outer edges, covered in a bolted steel skin plate with skin plate stiffeners to the north face (uppermost face when raised and horizontal), and incorporating five subsidiary sluice gates. The green-painted, steel gate guides are attached to the inside of the concrete guide beams.
STANDBY GENERATOR HOUSE: this single-storey, approximately L-shaped block is constructed of board-marked concrete treated in a similar way 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 up to the flat roof. The steps have circular-section handrails which continue round the edge of the roof, forming in effect a viewing platform. The west side has a deep, chamfered, brick plinth along its length and wrapping round the outer corners of the building. 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 a solid timber door, a horizontal, three-light window with timber frames, and large, louvred apertures for the generator room.
INTERIOR: the special interest is concentrated in the structural form of the buildings rather than the operating plant contained within the tidal surge barrier and the standby generator house.
TIDAL SURGE BARRIER: the counterweight wells in the towers are separated from the staircase wells by concrete walls with large, circular viewing apertures at each staircase landing. On the ground floor is a small, steel, spiral staircase with textured steel treads set to one side of a small lift in a wire cage. Above this level the staircase is a larger, triangular structure filling the staircase well and enclosing the lift, with angled flights of textured steel treads fixed in a hollow-section steel framework with circular, steel tube railings and landings to the inner, tower side. The control room contains an updated control panel* to control the barrier. The machinery rooms contain the replacement motors*, gear box*, spur gears* and counterweight chains*. The walkway has an internal triangular frame of steel, circular sections with horizontal I-section rolled steel joists.
STANDBY GENERATOR HOUSE: the walls are either painted board-marked concrete or plastered with orange-brown rectangular tiles to the corridor floor and solid timber doors to the rooms, which include a generator room, staff room, stores, and WCs.
* Pursuant to s1 (5A) of the Planning (Listed Buildings and Conservation Areas) Act 1990 ('the Act') it is declared that those aforementioned features are not of special architectural or historic interest.
MAPPING NOTE: the standby generator house includes the two staircases up to the flat roof and the deep, brick plinth into which the west staircase is set.
