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Moy, Aultnaslanach Viaduct

Railway Bridge (19-20th Century)

Site Name Moy, Aultnaslanach Viaduct

Classification Railway Bridge (19-20th Century)

Alternative Name(s) Aultnaslanach Moy Viaduct; Allt Na Slanaich Burn; Aultnaslanash; Dalriach Burn; Allt Creag Bheithen; Allt Creag Bheithin

Canmore ID 14134

Site Number NH73SE 16

NGR NH 76010 34937

Datum OSGB36 - NGR

Permalink http://canmore.org.uk/site/14134

Ordnance Survey licence number 100057073. All rights reserved.
Canmore Disclaimer. © Copyright and database right 2019.

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Digital Images

Administrative Areas

  • Council Highland
  • Parish Moy And Dalarossie
  • Former Region Highland
  • Former District Inverness
  • Former County Inverness-shire

Archaeology Notes

NH73SE 16 76010 34937

For corresponding road bridge (adjacent to NE), see NH73SE 12.

(Name cited as Aultnaslanash and location as NH 759 349). Opened 1897 by the Highland Rly. A 5-span wooden trestle bridge, the only one of its kind on a main-line railway in Scotland. Retained owing to the difficulty of securing foundations for a steel or masonry bridge.

J R Hume 1977.

This wooden trestle bridge carries the single-track Aviemore-Inverness railway across the Allt Creag Bheithen just N of the former station at Moy (NH73SE 19). This line was opened by the Highland Railway Company in 1897, and the bridge is now the only surviving structure of its type on a main-line railway in Scotland, possibly in Britain.

The bridge is 132ft 7ins (40.41m) in length by 28ft 6ins (8.69m) in width with raking shores spreading the width to 60ft (18.29m) overall. There are five spans, varying between 24ft 4in (7.42m) and 25ft 1in (7.65m) in length centre to centre, and the decking stands 27ft 9in (8.46m) above the normal water-line of the burn.

Compared with the elaborate structures of this kind erected by I K Brunel in England and those on North American railroads, this bridge is of modest trestle frame and multiple prop-and-beam construction, employing heavy pitch-pine baulks with iron-clad joints. The sectional corrugated-iron deck is carried on a series of six longitudinal girders, each made up of coupled baulks mounted on top of the other. There are six trestle bents, the two end ones being set within the embankments. Each of the four central frames is composed of six upright posts driven into the ground like piles and joined together by runners, beam-stiffeners and, at the head, a transverse beam. The main structural components are braced laterally by raking shores, and longitudinally by an elaborate system of raking struts associated with the main girders and a lower straining-beam.

G D Hay and G P Stell 1986.

This bridge carries the revised or 'direct' route of the Aviemore - Inverness portion of the Perth - Inverness (main) line of the former Highland Rly. across the Allt Creag Bheithen to the NW of Moy Station (NH73SE 19)and W of Loch Moy. It remains in regular use by passenger traffic.

Information from RCAHMS (RJCM), 8 May 1998.

This site has only been partially upgraded for SCRAN. For full details, please consult the Architecture Catalogues for Inverness District.

Information from RCAHMS (NMRS), March 1998.

(Formerly classified as Railway Viaduct). This bridge is depicted (but not noted) on the 1982 edition of the OS 1:10,000 map. It is adjacent to the former line of the A9 public road (now the B9154); the present line lies some distance to the SW.

Information from RCAHMS (RJCM), 28 March 2006.

Activities

Construction (1897)

Completed 1897. This is the last timber viaduct existing on a main line Scottish railway, a rare and substantial survivor of a once fairly common bridge type.

R Paxton and J Shipway, 2007.

Publication Account (1986)

This wooden trestle bridge carries the single-track Aviemore-Inverness railway line across the AlIt Creag Bheithen just N of the former station at Moy. This line was opened by the Highland Railway Company in 1897, and the bridge is now the only surviving structure of its type on a main-line railway in Scotland, possibly in Britain.

The bridge is 132ft 7 in (40.41m) in length by 28ft 6in (8.69m) in width with raking shores spreading the width to 60ft (18.29m) overall. There are five spans, varying between 24ft 4in (7.42m) and 25ft lin (7.65m) in length centre to centre, and the decking stands 27 ft 9 in (8·46 m) above the normal water-line of the burn.

Compared with the elaborate structures of this kind erected by I K Brunel in England, and those on North American railroads, this bridge is of modest trestle frame and multiple prop-and-beam construction, employing heavy pitch-pine baulks with iron-clad joints. The sectional corrugated-iron deck is carried on a series of six longitudinal girders, each made up of coupled baulks mounted one on top of the other. There are six trestle bents, the two end ones being set within the embankments. Each of the four central frames is composed of six upright posts driven into the ground like piles and joined together by runners, beam-stiffeners and, at the head, a transverse beam. The main structural components are braced laterally by raking shores, and longitudinally by an elaborate system of raking struts associated with the main girders and a lower straining-beam.

Information from ‘Monuments of Industry: An Illustrated Historical Record’ (1986).

Publication Account (2007)

Allt-na-Slanach Viaduct, Moy

(Institute Civil Engineers Historic Engineering Works no. HEW 0601/02)

This is a timber trestle viaduct erected to carry the single line from Inverness to Perth over the Allt-na-Slanach burn. It was completed in 1897 and provision was made for a double line of track. The designer was Murdoch Paterson and the contractor, John Ross & Son.

Timber was chosen to limit the weight of the structure on the marshy ground. The viaduct has five spans of 23 ft, the centre one spanning the burn. The structural form is simply-supported timber beams supported on four vertical posts across the width of the bridge. The spans of the beams

are reduced to about 11 ft by angled supporting struts to the posts at each end which are themselves braced by similar struts and longitudinal members at a lower level. This arrangement together with transverse raking struts at the sides provides essential stiffness.

In 2001 fungal decay was found in the timber and in the following year a £2.6 million programme of work was undertaken to protect the timber and strengthen the bridge. Specially designed concrete members were introduced to form a new structure on separate foundations such that no railway loading is now carried by the original structure, although it still supports the side gangways. It is the last timber viaduct existing on a main line Scottish railway, a rare and substantial survivor of a once fairly common bridge type.

R Paxton and J Shipway, 2007.

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

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