Dornoch Firth Bridge

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Dornoch Firth Bridge
Dornoch Firth Bridge (west side) - geograph.org.uk - 286814.jpg
Dornoch Firth Bridge in November 2006
Other name(s) Dornoch Bridge
Carries A9, two footways, two cycle tracks
Crosses Dornoch Firth
Locale Tain
Designer Christiani & Nielsen
Engineering design Sir Alexander Gibb & Partners, Tony Gee & Partners
Design Prestressed box girder on inclined leg portals
Material Concrete
Total length 892 metres (2929 feet)
Width 13.2 metres
Number of spans 21
Piers in water 20
Constructed by Christiani & Nielsen
Construction begin late 1989
Construction cost £13.5 million
Opened August 1991
Inaugurated 27 August 1991
Replaces 26 round-trip via Bonar Bridge
Coordinates 57°50′38″N 4°06′36″W / 57.844°N 4.11°W / 57.844; -4.11Coordinates: 57°50′38″N 4°06′36″W / 57.844°N 4.11°W / 57.844; -4.11
Dornoch Firth Bridge is located in Highland
Dornoch Firth Bridge
Red pog.svg Kylesku Bridge shown within highland
grid reference NH747852

The Dornoch Firth Bridge is a road bridge over the Dornoch Firth, carrying traffic between Tain and Dornoch.

History[edit]

It was built for the Scottish Office. There had been recent substantial improvements of the A9 between Inverness and Tain, including the cable-stayed Kessock Bridge at Inverness in 1982. The Dornoch Bridge was to be the final link in the chain. Tenders were open to bid from 1986. 40 companies showed an interest in the contract. Ove Arup and Crouch Hogg Waterman of Glasgow produced a set of initial design parameters for companies to build. The joint-venture chosen to build the bridge put in a quote for £9.5 million, and won the contract in early 1988.

Design[edit]

Each of the 21 spans is about 44 metres long.[1] The Project Manager was Nigel Beaney of Christiani & Nielsen. Pre-stressed concrete rather than steel was chosen as the material to improve the life of the bridge. The design had to be approved by the Royal Fine Art Commission for Scotland.

Construction[edit]

It was built by a joint venture of Christiani & Nielsen. It cost £13.5 million (£25 million current value). At the time it was one of the longest bridges in Europe built with the cast-and-push method, or incremental launch.

The bridge deck was built in a temporary factory 20 metres south of the southern end of the bridge. Each section of the bridge was pushed with 600 tonnes of hydraulic force over PTFE bearings on the top of the bridge supports. The launch nose section[2][3] had a light steel composition to reduce the cantilever moment as it was inched over an open span. Each deck section was constructed as around 21 metres in length - half a span. The concrete used welded mat reinforcement. The pres-stressing of each section had 38 Macalloy bar tendons of 40mm thickness. The sections would be cast on a Monday morning and pushed on a Friday, this later being on a Thursday. Each deck section weighed around 14,000 tonnes.

Plaque for the bridge's opening in 1991

Opening[edit]

It was opened by Queen Elizabeth The Queen Mother on Tuesday 27 August 1991. The bridge replaced, via a roundabout with the A836 to the south and a road junction with the A949 to the north, the 26-mile round trip over Bonar Bridge.

See also[edit]

References[edit]

Aerial view in August 2004

External links[edit]

Video clips[edit]