Erskine Bridge, Clydebank Waterfront, Renfrewshire/West Dunbartonshire

Description

The Erskine Bridge (1967-71) is a large, mono cable-stayed motorway road bridge spanning the River Clyde, 12 kilometers west of Glasgow. It is part of the A898 spur of the M8 motorway heading northwards across the Clyde into West Dunbartonshire.

The bridge was designed by Freeman Fox & Partners for the Erskine Bridge Joint Committee. Dr Oleg Kerensky was the partner in charge and the chief design engineer was Dr William Brown under the supervision of Sir Gilbert Roberts. The piers and foundations were designed by W. A. Fairhurst & Partners. The consultant architect was R. E. Slater.

The central span is 305m (1000ft) flanked by anchor spans of 110m each. The total length including approach spans is 1322m. The aerofoil box-girder deck is supported by fourteen diamond-plan, single-shaft concrete piers at a maximum height of 45m above the river. Two central pylons extend 38m above the level of the deck. A 6x4 cluster of galvanized steel cables passes over the saddle of each pylon in a centralised, single plane.

The dual carriageway has cycle lanes and footpaths with metal safety barriers, renewed in 2012. The underside of the deck carries four water mains pipes and two gas pipes. In 2017 the cables were painted and aluminium lighting columns were installed.

Statement of Interest

The Erskine Bridge (1967-71) was a state-of-the-art infrastructure landmark in Scotland for its time and remains one of the country's most architecturally and technically distinguished bridges of the post-war period and beyond its date of construction. It is the first example of a large-scale cable-stayed bridge in Scotland and is recognised for its structural simplicity, economy of materials and slender appearance. The bridge was designed and built during a period of substantial development in civil engineering and road infrastructure. It illustrates the aspirations for economic and social progress in Scottish society and is directly associated with the period of ambitious transformation of Scotland's modern infrastructure during the 1960s.

The Erskine Bridge is one of only three road bridges in Scotland with a main span exceeding 300 metres. Its minimalistic single-cable design remains exceptionally rare for large-scale road bridges. On completion, the Erskine Bridge is understood to have had the longest span of this type in the world. The appearance of many bridges on this scale have been altered by later alteration and engineering works. The largely unchanged appearance of the Erskine Bridge contributes to its special interest.

Age and Rarity

The Erskine Bridge was designed from 1963 and built between 1967 and 1971. It was part of a strategic and highly ambitious expansion of the new motorway network in Scotland, which had become the devolved responsibility of the Scottish Office after 1956, and formed part of the United Kingdom's major post-war infrastructural investment in the new road and motorway networks.

An integrated road network was seen as a priority in and near Scotland's largest areas of population where the use of private cars and the need for commercial road transport was pressing. The most important scheme in the west of Scotland during this period was the opening of the M8 in 1965, completed through Glasgow and further connecting the Greater Glasgow area to the west through to the airport at Abbotsinch, on to Greenock and then back over the Clyde at Erskine. The infrastructure scheme for the M8 and the Clyde, which included the building of the Kingston Bridge, the Erskine Bridge and the Clyde Tunnel, were, along with the Tay Bridge (1966) and the Forth Road Bridge (1964) in the east of Scotland, the most significant projects of the time.

The need for a bridge to replace the Erskine Ferry on the Clyde was established before the Second World War, leading to the formation of the Erskine Bridge Joint Committee in 1963. The bridge is part of the A898 (M898) spur of the M8 heading northwards across the Clyde into West Dunbartonshire. This strategically important north-south link was part of a blueprint for the industrial revitalisation of the central belt, at a time when the Upper Clyde was still considered a major shipping channel. Hunterston Power Station in North Ayrshire was a focal point for this industrial activity.

It was agreed that a span of 300 metres and a clearance height of 45 metres was required so that larger ships, including the Queen Elizabeth II liner then under construction at the Clydeside shipyards, could pass beneath. The committee appointed Freeman, Fox & Partners as consulting engineers for the bridge and work began on the foundations in 1967. The Erskine Bridge was officially opened by Princess Anne in 1971. The cost on completion was 10.5 million pounds.

Cable-stayed bridge construction, in its modern form, was pioneered in the mid-1950s. The technology allowed spans greater than 200 metres to be traversed without the super-structural cost associated with suspension bridges. The interest in the cable-stayed bridge type has increased steadily and it is now a common choice for medium to long road bridges. The four main classes of rigging on cable-stayed bridges are mono, fan, harp and star.

The majority of large post-war cable-stayed road bridges use harp or fan formations, due in part to the opportunity for visual variety in the way the cables and pylons can be configured. The minimalistic mono, or single-cable, configuration is one of the lesser-used classes and has been very rarely used for large spans on the scale of Erskine Bridge.

A direct forerunner of the Erskine Bridge was the First Severn Crossing (also by Freeman Fox and Partners in association with Mott Hay Anderson) connecting England and Wales over the Severn estuary. The crossing consists of the Severn suspension bridge (1961-66, listed Grade I) and the Wye cable-stayed bridge (1966, listed Grade II). With a main span of 234 metres, the Wye Bridge was one of the earliest anywhere in the world to use a mono cable in a single plane. Replacement cables were later added to the Wye Bridge and the pylons were heightened in the late 1980s as part of a strengthening programme.

During construction of the Erskine Bridge, four box girder road bridges partially collapsed giving rise to concern on the reliability of this bridge type. One of these was the West Gate Bridge (formerly the Yarra Bridge), Melbourne which was also by Freeman Fox & Partners and similar in design to the Erskine Bridge. Following a formal inquiry, the reason for its collapse was cited as a failure in construction not in design. In 1974, a government committee headed by Sir Alec Merrison identified the need for more stringent codes of practice and independent design checks for box-girder bridge construction. As a result, many box girder bridges in the United Kingdom were strengthened to reflect the findings of the Merrison Report. Regardless of actual need, an eighteen month programme of strengthening works was carried out at Erskine Bridge, including reinforcement of critical box girder members and restressing the cable stays, without changing the appearance.

While road bridges are not a rare building type in Scotland, the Erskine Bridge is one of only three with a main span exceeding 300 metres making it an important bridge-building landmark. At the time of its completion in 1971 it had the longest cable-stayed span of its type in the world (Manser, p.70). Since then, mono cable-stayed bridge design has rarely been used for road bridges on this scale and it is therefore an unusual example of its type. Its innovations foreshadow later development in cable-stayed bridge design including the Millau Viaduct (2004) in France, an immensely tall and long harp/fan cable hybrid by Michel Virlogeux and Norman Foster.

Architectural or Historic Interest

Interior

N/A

Plan form

The general linear plan form of the Erskine Bridge is typical of its building type. It has a gentle curving alignment to the north and south approaches which also adds to its design interest. The slender and aerodynamic diamond-plan supporting piers were designed specifically for this bridge by W. A. Fairhust. This wind reducing measure is a significant element of the broader design, adding to the special interest of this bridge.

Technological excellence or innovation, material or design quality

The Erskine Bridge is both a monumental and elegant design that has sensitively used modern materials and applied civil engineering to great aesthetic effect. It is also a substantial technical achievement within the context of the development of bridges in Scotland and the United Kingdom. At the time of its design, the Erskine Bridge had the longest span of its bridge type in the world.

The bridge was quickly recognised in the engineering press of the day for its 'extreme slenderness and the low weight of steelwork in relation to its span' (Horne, p.336), and as a 'self-effacing structure […] taking the Clyde in a delicate stride and touching the ground in the lightest way' (Manser, p.70). The use of a consultant architect, in this case R E Slater who also advised on the architectural aspects of the Humber Bridge project, contributed to the elegant appearance of the bridge. It received the premier design award in the 1972 Structural Steel Design Competition (Metal Construction and British Welding Journal, Volume 5, p.63).

The chief design engineer, Dr William C Brown (1928-2005) is credited with inventing the aerodynamically stable 'aerofoil' deck and adapting it for Erskine Bridge. According to Brown, who worked for Freeman Fox & Partners from 1956 to 1985, 'the deck configuration of Erskine Bridge is a particularly good example of deriving strength through shape.' (Brown, p. 266). The weight of the deck and combined asphalt road covering at the Erskine Bridge is as low as 141 pounds per square foot, allowing the aerodynamic supporting piers to be remarkably tall and narrow even by today's engineering standards. At 45 metres between the river and the roadway, the bridge held the record for the highest clearance in Scotland until the opening of the Queensferry Crossing in 2017.

The Erskine Bridge was built simultaneously from both sides to meet midway above the Clyde. An innovative, cantilevered construction system was specifically developed for the project. This allowed eighty box-girder sections to be lifted successively onto self-levelling trolleys and then rolled over the top of the deck. Each box was then lowered into position by means of specially designed cradles before being welded into place.

Other bridges by Freeman Fox & Partners erected in the United Kingdom during the second half of the 20th century include the Forth Road Bridge (1958-64 – listed Category A - LB47778) and the Humber Bridge (1964-81 – listed Grade I). Oleg Kerensky (1905-1984) oversaw the delivery of many of the company's major bridges and was highly respected among the engineering profession (Wex, p.2). Kerensky was instrumental as partner in charge and his expertise in bridge building and motorway planning also played an important part in the design of the Erskine Bridge. During the 1970s and 1980s he chaired the British Standard bridge committee, working towards the production of the British code of practice for the design and construction of steel, concrete and composite bridges.

Setting

Due to its exceptional height and length, the Erskine Bridge is a prominent landmark which has been positively described by a number of sources. The RIAS Guide: North Clyde Estuary states that it is 'elegant in distant landscape views' (p.16). The Buildings of Scotland: Lanarkshire and Renfrewshire notes that the structure is 'splendidly dramatic in its estuarial landscape' (p. 527). The open river valley landscape setting has not altered significantly since the bridge was constructed.

There are inter-visual relationships between the bridge and the two Old Kilpatrick conservation areas to the north and the Boden Boo woodland park to the south. The 'Old Kilpatrick – Linnvale' section of the Forth and Canal (Scheduled Monument 6778) and the North Clyde railway line pass underneath the structure on the West Dunbartonshire side, adding to the industrial heritage group value. The Antonine Wall World Heritage Site and its buffer area also lie approximately 300 metres to the north of the bridge on elevated ground.

Regional variations

There are no regional variations associated with this bridge.

Close Historical Associations

There are no known associations with a person or event of national importance at present (2018).

External Links

Historic Environment Scotland Listing

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