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Lugar Water Viaduct
Cumnock, Ayrshire, Scotland, UK
associated engineer
John Miller
date  1848 - 1850
era  Victorian  |  category  Railway Viaduct  |  reference  NS573206
ICE reference number  HEW 2433/05
An elegant ashlar masonry viaduct that carried the Glasgow & South Western Railway over the Lugar Water, in an area peppered with coal workings. The structure is also known as Templand, Bank or Woodroad Viaduct. It is still in service on the Kilmarnock to Dumfries section of the main line from Glasgow to Carlisle.
Lugar Water Viaduct was designed by engineer John Miller (1805-83) and is constructed of local white sandstone. It is located some 80km from the railway’s terminus at Glasgow, on strata of limestone and coal.
Coal had been mined locally in ‘stoop and room’ fashion — stoops, or pillars, of coal are left to support the roof of the excavated workings, or rooms. Some of the viaduct’s piers were founded on top of such workings, which raised concerns regarding their stability. Consequently, the cavities were cleared of debris and packed firmly with selected dry stone. Evidently, the work was done well as the piers have not settled over time.
The viaduct is 229m long and reaches a greatest height of 49.2m, from foundation level to the top of the parapet, though the average height is 28.8m. The structure is level, approached by gradients of 1 in 200 at the north end and 1 in 150 at the south end.
It has 14 semicircular ashlar arches, nine of 15.24m span in the centre and five of 9.1m span — three at the north end and two at the south. The design of the arches is such that the thrust pressure line is close to the centre of each arch ring. For the main arches, the rings are only 610mm thick (one twenty-fifth of the span), making a calculated horizontal pressure on the keystone across the arch of about 254 tonnes.
Following Thomas Telford’s (1757-1834) practice, the viaduct has hollow piers and spandrels, reducing the weight bearing on the foundations. Piers between the larger arches are 2.1m thick at the top with a central void 610mm wide, while piers between the smaller arches are 1.5m thick at the top with a 300mm void.
The smaller arches are separated from the main ones by abutments 5m thick. The abutments at either end of the whole structure, where it joins the embankments, are 7m thick.
Derrick cranes were used to build the piers and abutments to 7.6m above ground level. Above that height, a horse-drawn tramway for transporting stone was constructed on an elevated service road, with travelling cranes running on rails either side of the viaduct.
Particular attention was paid to the erection of the timber centring (formwork for the masonry arches), more than 30m high. The weight of a finished 15.24m span arch was computed at over 1,000 tonnes, exerting a pressure on the foundation of 68.4 tonnes per sq m.
The viaduct contains 14,150 cu m of masonry, weighing 34,040 tonnes. It cost about £30,000 to construct, with the centring costing some £4,500. Miller considered it to be his greatest work. It has been a Category A listed structure since April 1971.
In 2010 the Woodroad Regeneration Forum and Network Rail began working together to safeguard Lugar Water Viaduct for the long term, with future upgrading works planned. On 25th September 2010, Cathy Jamieson, MP and MSP, unveiled a plaque to commemorate the 160th anniversary of the viaduct's construction.
Contractor: James McNaughton
Research: ECPK
"The Lugar Valley Viaduct, on the line of the Glasgow and South-Western Railway, erected from the design of John Miller, Esq., C.E." by John Cameron, October 1851, in Transactions of the Royal Scottish Society of Arts, Vol.IV, pp.100-107, Adam and Charles Black, North Bridge, Edinburgh, 1856
reference sources   CEH SLB

Lugar Water Viaduct