Kylesku Bridge

Kylesku Bridge Drochaid a' Chaolais Chumhaing
File:Le pont de Kylesku.jpg
Coordinates	grid reference NC233330
Carries	A894, one footway
Crosses	Loch a' Chàirn Bhàin (Caolas Cumhann)
Locale	Kylestrome
Characteristics
Design	Prestressed box girder
Material	Concrete
Total length	276 m (906 ft)
Longest span	79 m (259 ft)
No. of spans	5
Clearance below	24 m (79 ft)
History
Engineering design by	Ove Arup
Construction start	August 1982
Construction cost	£4 million
Opened	July 1984
Inaugurated	8 August 1984
Replaces	Kylesku and Kylestrome ferry
Location

The Kylesku Bridge (officially known since 2019 by its Gaelic name Drochaid a' Chaolais Chumhaing) is a distinctively curved concrete box girder bridge in northwest Scotland that crosses Caolas Cumhann (Gaelic for "narrow strait", pronounced "Kyles Cuan"); the channel that connects Loch Glencoul and Loch Glendhu with Loch a' Chàirn Bhàin in Sutherland. It is listed as category A, the highest grade.

History

In June 1978, the Highland Regional Council asked Ove Arup & Partners Scotland to prepare a feasibility study for a bridge, in their capacity as consulting civil engineers, and it was prepared by March 1979.

Construction for the approach roads, costing £4 million, began in summer 1981. Construction of the bridge began in August 1982, with Morrison Construction and Lehane, Mackenzie and Shand the chief contractors.

It was constructed by building out the supporting legs and then lifting into place the central span, which weighed 640 tonnes (630 long tons; 710 short tons).

The cost of the bridge was £4 million, although was earlier budgeted at £2.75 million. The bridge opened to traffic in July 1984, and was formally opened by the Queen on 8 August 1984.

In 2019, the bridge was classified by Historic Environment Scotland as a Category A structure, recognising it as "visually striking and technically innovative". It was also officially renamed to the Gaelic translation of its name, Drochaid a' Chaolais Chumhaing.

Geography

The bridge crosses water which is approximately 120 metres (390 ft) wide and up to 25 metres (82 ft) deep, leading to fast tidal currents. It replaced the ferry between Kylesku and Kylestrome, which was approximately 400 metres (1,300 ft) to the east.

Design

The bridge is 275 metres (902 ft) long with a 79-metre-long (259 ft) main span. The bridge deck is at a height of 24 metres (79 ft) above high water to provide navigation for ships.

The bridge deck is supported by V-shaped inclined piers, with eight inclined legs, in order to reduce the length of the main span. The lateral forces from each leg balance, so the total force on the foundations is vertically downwards. The spread of legs supports the bridge in winds which can exceed 100 mph (160 km/h; 45 m/s; 85 kn), and also loads resulting from the curvature of the bridge. There is no joint between the legs and the deck of the bridge, with the expansion joints and bearings being located at the abutments to facilitate straightforward maintenance. The legs are formed from reinforced concrete and the deck from prestressed concrete using cables tensioned at up to 52,200 kN.

The bridge is designed to be sympathetic to the surrounding country, and the approaches were chosen to minimise changes to the landscape.

External links

• Construction at night

Video clips

• Aerial view in 2012
• View in 2009
• Former ferry in 1966