Civil Engineering heritage: Scotland - Highlands and Islands

Date 2007

Event ID 963178

Category Descriptive Accounts

Type Publication Account

Permalink http://canmore.org.uk/event/963178

Ve Skerries Lighthouse, Papa Stour, Shetland

(Institute Civil Engineers Historic Engineering Works no. HEW 2452)

This 50 ft tall pre-stressed reinforced-concrete lighthouse was constructed in 1979 at a remote and exposed location, mainly as a navigational aid to tanker traffic in and out of Sullom Voe oil terminal.

Construction was achieved in the remarkably short time of four months by means of helicopters. This technique was used only after the practicability of helicopters for lifting and positioning 9.84 ft diameter pre-cast concrete manhole chamber rings weighing about a ton to be used as permanent

shuttering had been tested.

An unusual design feature was that the tower was prestressed vertically with a post-tensioning force of about 1600 tonnes nearly ten times the weight of the structure. This was achieved by means of Macalloy bars anchored from 10–16 ft into the rock beneath, tensioned from the top by hydraulically operated compressed air jacks. The tower was designed to withstand a wave force of 2 tons sq. ft for the bottom 25 ft tapering off to 12 ton sq. ft at the tower top.

A lighthouse at this site was considered as early as 1863 but not implemented. Using traditional methods it would have taken several years to build. This innovative project, directed by Northern Lighthouse Board civil engineer R. Mackay, was the first of several using the post-tensioning technique in Scotland.

R Paxton and J Shipway, 2007.

Reproduced from 'Civil Engineering heritage: Scotland - Highlands and Islands' with kind permission from Thomas Telford Publishers.