Articles
The Kincardine Bridge:
Celebrating 85 Years
A985
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The Kincardine Bridge is a road crossing of the River Forth, located 8 miles south east of Stirling. Completed in October 1936, it remains an important link in the trunk road network and a fitting monument to Scottish engineering.
The need for a new bridge was first discussed in the 1920s, particularly as demand for cross-river travel increased. Sir Alexander Gibb & Partners were appointed in 1930 to prepare a design for the crossing which, for a time, would become Scotland’s longest road bridge. Its completion led to significant reductions in congestion in Stirling and improved road communications throughout the heart of the country. Until 1988, the crossing was operated as a swing bridge.
Today, the Category A listed bridge carries in excess of 10,000 vehicles every day and connects the M876 motorway with the A985 trunk road.
Key Data
Location
A985, Falkirk
and Fife
Consulting Engineer
Sir Alexander Gibb
and Partners
Construction
December 1933
to October 1936
Project Cost
£327,000
(£24 million today)
Planning and Design
Discussions on the need for a road bridge across the River Forth began in the 1920s. Traffic crossing Stirling Bridge on the A9 was increasing at considerable pace, causing congestion on the city’s streets. Options for road traffic seeking to cross the river were limited, with only a handful of ferry services in operation at Queensferry, Kincardine and Alloa. A detour of around 50 miles was faced by east coast traffic when these were out of service.
In 1925, a report was submitted to the Ministry of Transport (responsible for roads in Scotland until April 1956), detailing the possibilities for a new road bridge at Alloa or Kincardine. Despite Kincardine offering greater advantages, uncertainty over ground conditions led to Alloa being chosen as the preferred option. Engineering consultant Mott, Hay & Anderson were appointed to prepare plans however progress was limited due to economic constraints..
In 1930, Fife County Council instructed Sir Alexander Gibb & Partners to produce a feasibility report on the construction of a bridge at Kincardine. Information from bore holes undertaken in 1890 as part of a proposed rail tunnel gave confidence that ground conditions were suitable for a new bridge. In June 1930, at a meeting attended by representatives of the Ministry of Transport, the Counties of Fife and Clackmannan and the Burghs of Dunfermline, Falkirk, Alloa and Stirling, it was agreed that a joint report on the each location should be prepared. The report, submitted in August, demonstrated that the Kincardine option offered the greatest benefits, and that it would be cheaper to construct. A Joint Board, tasked with the delivery of the new bridge, was formed shortly after.
Northern spans of the bridge under construction in 1936. Photo taken from the swing-span central support. © Newsquest (Herald & Times).
A parliamentary hearing was held in Edinburgh in March 1931 to consider the new bridge. Following discussions, the scheme provided for a bridge 2,696 feet long with a swing-span giving two openings of 150 feet for river traffic. Maximum headroom of 30 feet above high water was allowed for under the closed swing-span. Approach roads of 2,200 and 500 yards were proposed at each end, with a 700 yard long bypass of Kincardine also outlined. Vessels of up to 2,000 tons would be able to pass through the open bridge. The Ministry of Transport initially offered grant assistance of 85% towards the cost of the project, though this was later reduced to 75% due to the national economic situation.
The bridge was approved on 8th July 1931 and tenders were issued in December of that year. Of the twelve prices returned, the Cleveland Bridge and Engineering Company was lowest with a combined tender of £238,609. Construction was finally approved in September 1933 and works began on site that December.
The bridge is a multi-span structure and constructed of both steel and concrete. Its design varies from span to span and was originally summarised in a 1936 technical paper as follows:
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(From north to south) Three continuous spans of 62’6” over the L.N.E Railway on a curve of 520 feet radius. A curved approach was required for connection to the north approach road.
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Seven steel spans of 100 feet, constructed as a system of cantilevers with 50 feet girders in alternate spans. This economic and convenient method form of construction “lent itself admirably to the adoption of the arched shape of girder which is a characteristic feature of the design”.
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A steel swing-span of 364 feet of the Warren Truss type, symmetrically balanced on a centre pier at midstream (Pier 11). The structure is protected from shipping by a timber jetty 470 feet long and 50 feet wide.
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Seven further steel spans of 100 feet.
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Nine reinforced concrete spans of 50 feet with an arched underside similar to that adopted for steel spans.
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A 265 feet long piled reinforced concrete viaduct.
The structure has 19 reinforced concrete supports of varying dimensions and styles, many of which are founded on rock.
The SS Roken passes the bridge in February 1949. Two channels, each 150 feet wide were provided for vessels of up to 2,000 tonnes. © The Scotsman Publications Ltd.
The bridge deck is made up of two 5 feet wide footways and a 30 feet wide carriageway, edged with granite kerbs. Two concrete portals mark the extents of the swing-span and include sliding gates each weighing 4 tonnes.
The swing-span, the longest in Europe at the time, weighs 1,600 tonnes. Its mechanism was electrically powered by two 50 horse power DC motors with a backup diesel generator available in case of power failures. At the push of a button the turning machinery was quickly brought into action. The rollers located beneath the structure were machined to a very high accuracy and enabled to opening of the bridge to be completed in only a few minutes. To lock the bridge in place, hydraulically operated locking bolts were provided. The design included for a control room and engine room, ultimately positioned above and below the swing-span.
Construction
Construction of the bridge began in December 1933 and was completed less than three years later on 29th October 1936. At its peak, the site employed more than 200 men with no major accidents recorded during the contract.
Initial works involved the installation of piles for the bridge supports and the construction of temporary timber access bridges from each shore. These were provided with tracks to aid the movement of materials and plant, including cranes. Construction of the reinforced concrete piers at the north shore involved the use of caissons, founded on solid rock. Excavated material was loaded into wagons and removed from site via the timber bridges. A 150 feet wide opening in the river channel was maintained for shipping throughout the works. Works on some piers was complicated by water making its way into the cylinders and eventually a system utilising compressed air was utilised.
The permanent timber jetty was completed by the autumn of 1935. Constructed of creosote treated high quality Canadian Douglas Fir, its purpose was to protect the structure when in the open position.
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The bridge control room was finished to a high standard and designed to operate 24 hours a day. Its position high above the carriageway provided operators with unobstructed views of both the bridge and the River Forth.
More than 4,000 tonnes of steel and 150,000 rivets were used in the construction of the bridge. Steelwork was supplied to the site by rail by Sir William Arrol and Co of Glasgow and was designed to Ministry of Transport loading requirements. Some girders were so long they had to be delivered in smaller sections and bolted together. Erection of steelwork took place using cranes operating on the tracks of the temporary bridges.
The swing-span was completed in mid-1936 and was a fine example of both structural and mechanical engineering. It was erected in the open position to maintain shipping channels and was finished to a very high standard. A trial erection was undertaken at the fabrication yard prior to its transport to the site. Minimum headroom for vehicles travelling on the bridge is 18 feet, accessed via two concrete portals. These are adorned with the coats of arms of Stirling, Fife and Clackmannan and the name of the bridge is displayed in bronze lettering. Each portal is fitted with a gate, lowered to keep traffic off the swing-span. The gates, which have an ornamental finish, weigh almost 4 tonnes each.
The bridge control room was positioned 30 feet above the carriageway in the centre of the swing-span. As 24 hour operation was required, it was fitted with mess and welfare facilities for bridge staff. Operators were given an uninterrupted view of the bridge through the use of large windows on all sides.
Contract Summary
Contract
Main Contractor
Contract Value
Bridge Foundations & Superstructure
The Cleveland Bridge & Engineering Co.
£241,000
South Approach Road
A.A Stuart & Sons
North Approach Road
George Bald
Bypass Road
J. Baxter & Sons
£35,500
(combined value)
The bridge was provided with ornamental lamp standards complete with 20 inch Morocco-glass globes. Profiled parapet railings were installed and all steelwork was painted to a high finish.
Construction of the approach roads was completed well in advance of the bridge opening dates. In the south, a new single carriageway linking to the existing Grangemouth to Stirling route was constructed. Today, this forms part of the A985 and M876. In the north, a new section of road linking the bridge to the Dumfermline to Alloa route was constructed. A bypass of Kincardine town centre was also constructed, known today as Feregait.
The bridge was opened to traffic at noon on the 29th October 1936 by the Conveners of Fife, Stirlingshire and Clackmannanshire. It was immediately popular and within a week was being used by more than 1,200 vehicles per day.
At its peak, the bridge was opened more than fifty times per month, a process that could take up to twenty minutes to complete. By the 1970s and 80s this resulted in congestion as vehicles waited to cross and created more than a few irate drivers! By 1987, more than 20,000 vehicles were using the bridge every day.
In the period from 1936 to 1988, four men served as Bridge Master at Kincardine. The first, Mr James Boyd, would later receive his British Empire in the bridge control room. The third, Mr George Reid, worked on the bridge for more than forty years. Those based at Kincardine had responsibility for other swing-bridges in Scotland, including Inchinnan and Banavie.
Final Opening
By the 1980s, the bridge’s mechanical components were obsolete and in need of modernisation. A slump in river traffic, combined with the high cost of refurbishment led the Scottish Office to propose that the bridge be permanently closed shut. Despite protests from locals and former bridge staff, the proposal was approved in 1987 following a public enquiry.
On Sunday 31st January 1988 the bridge swung open for the last time. Hundreds gathered for the occasion, including keen transport photographer Donald Stirling who shared the images below.
Works to fix the bridge in position were completed by the end of 1989, with the control and engine rooms preserved as a museum.
In 1987 it was decided that the bridge would be permanently closed to river traffic. On 31st January 1988, the bridge swung open for the last time. Hundreds of onlookers gathered for the occasion. © Donald Stirling
You can view more of Donald's photos from the event here.
The Bridge Today
The Kincardine Bridge is now managed by Transport Scotland on behalf of the Scottish Ministers. More than 10,000 vehicles still use the bridge each day.
In 2008, it was joined by its upstream companion the Clackmannanshire Bridge, designed to improve the traffic situation throughout the region and bypass Kincardine town centre.
Historic Environment Scotland listed the bridge as a Category A structure in February 2005, recognising its unique architectural and technical features. The bridge is a key link in the Scottish trunk road system and a series of multi-million pound projects are planned to ensure it remains open to vehicular traffic for decades to come.
The bridge deck was refurbished and new street lighting installed in the late 2010s. A programme of steelwork painting and the replacement of the piled south approach viaduct will commence in 2022.
From the Archive
Films
A short documentary was produced in the late 1980s to chart the history of the bridge. It also discusses its permanent closure. A copy was recently uploaded to YouTube and can be viewed below.
Further Reading
This article was first published in October 2021. Updated March 2023.
Related Content
A special podcast celebrating the 85th anniversary of the bridge was released in October 2021. It can be heard below.