SCRCA Primary Reference: Review of drawing-sac-mr-bridge-66-na-rail-491-1158-66-no6

Submitted by mark.harvey / Thu, 20/02/2020 - 21:50
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The document takes the form of a single folded sheet contained in a bound book of drawings that itself forms part of a set of seven books. The set covers all of the bridges (including viaducts, tunnels and major culverts) within Contracts 1 to 4 (i.e. the entirety of the Settle and Carlisle Railway). This sheet (page) is a partly colour-washed scale drawing that depicts a complete side elevation of Bridge 66, Batty Moss Viaduct a.k.a. Ribblehead Viaduct (Location ID 247780).

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The larger version will repay close examination and the following are especially worthy of note:

  • The title on the drawing (top-left) is "M.R. Settle to Carlisle Railway No.1. Batty Moss Viaduct at 13 Miles".
  • The drawing is undated, but it almost certainly formed part of the contract documentation and / or the working documentation associated with the construction of the Settle and Carlisle Railway between 1869 and 1876.
  • The drawing does not include any mention of the engineer or architect, although this information may be available elsewhere in the book in which the original is bound.
  • A scale of "10 Feet to 1 Inch" is indicated by original text and it is clear that the original was drawn to scale.
  • Key dimensions (in feet and inches) are indicated by text and accompanying arrows. There is an accompanying (original) note, which reads: "N.B. All dimensions parallel to centre line are given as though the Viaduct was on a straight line and are the mean dimensions; to obtain the dimensions at ends of piers a correction must be made by adding or deducting ½ the difference shewn on General Plan.".
  • The ground surface depicted on the drawing undulates significantly and the largest 'height' (i.e. the largest distance between original ground surface level and formation level) depicted on the drawing is between piers 20 and 21. (In the real world, this is no longer the case as the ground below and adjacent to the viaduct has been significantly altered during several phases of viaduct maintenance and rennovation work.)
  • All of the abutments and piers have foundations that are well below the ground surface. The depths of the foundation bases below the ground surface varies significantly. (The foundations were set into bedrock, although this is not depicted on the drawing.)
  • The piers are numbered from left / southeast (1) to right / northwest (23).
  • The end abutments and arches are not numbered. There are two abutments (one at each end) and 24 arches.
  • The end abutments are a similar height to the piers and the drawing clearly shows that they were partially buried by the sloping ends of the adjoining embankments.
  • The thickness given for the king piers at the lower bonding course is 21'10", which is just over twice the thickness of 9'10" given for normal piers.
  • The thickness given for the king piers at the upper bonding course is 12'0", which is just under twice the thickness of 6'6" given for normal piers. (The degree of taper for the king piers is therefore slightly different to the degree of taper for the normal piers.)
  • The inside diameter of the arches (measured at the springing points) is given as 45'0" and the rise of the arches is given as 18'0".
  • A label above the parapet wall states "INCLINATION 1 IN 100".
  • There is a difference in the height of the 'formation level' between the south and north ends of the viaduct. This is approximately 13.4 feet (1046.52 minus 1059.92), although the figure is only an approximation because the measurement points on the drawing do not correspond precisely with the ends of the viaduct. However, the figure of 13.4 feet is a lot less inacurrate than the figure of 12 feet that is often quoted in secondary sources (and it is reasonably close to the value of 13.28 feet obtained by dividing the length of the viaduct by the ruling gradient).
  • The rate of progress with the construction work is indicated by a set of annotations, neatly handwritten in red ink. The relative order and rate of progress is especially interesting:
    • The earliest date recorded on the drawing is Sept 1870 (for the footings for piers 12 and 13). The latest date recorded on the drawing is May 31st 1873 (for the top of pier 13).
    • Dates are provided for the completion (up to springing height) of piers 13 to 23 and for the northwest abutment There are no dates recorded for the completion of the southeast abutment or for piers 1 to 12. Pier 12 (a king pier) had reached approximately two-thirds of its height by May 31st 1873.
    • The start-dates for the foundations of the end abutments and piers contradict the statement made frequently in secondary sources that construction work commenced at the north end of the viaduct. If the dates recorded on this document are correct, work actually started with a pair of piers that are now in the middle of the structure, namely piers 12 and 13 (and it was probably one of these piers that featured in the official ceremony on 12th October 1870, when William Ashwell formally 'laid the first stone'). The dates given for the foundations levels are as follows:
      • South abutment: May 1872.
      • Pier 1: Sept 1872.
      • Pier 2: Oct 1872.
      • Pier 3: Nov 1872.
      • Pier 4: Dec 1872.
      • Pier 5: Dec 1872.
      • Pier 6 (king): Nov 1872.
      • Pier 7: Oct 1872.
      • Pier 8: May 1872.
      • Pier 9: May 1872.
      • Pier 10: May 1872.
      • Pier 11: May 1872.
      • Pier 12 (king): Sept 1870.
      • Pier 13: Sept 1870.
      • Pier 14: Oct 1870.
      • Pier 15: Oct 1870.
      • Pier 16: Feb 1871.
      • Pier 17: Feb 1871.
      • Pier 18 (king): April 1871.
      • Pier 19: May 1871.
      • Pier 20: June 1871.
      • Pier 21: Undated.
      • Pier 22: April 1871.
      • Pier 23: April 1871.
      • North abutment: March 1871.
  • The footings for piers 1 and 6 are dual-level. One feasible (and likely) explanation for this is that there was a 'gryke' in the underlying limestone bedrock at each of these locations.
  • Ten tie bolts and pattress plates have been depicted as red circles. These were added during strengthening works, as indicated by the associated annotation on the drawing, which reads "Tie Bolts & Plates fixed & work completed Jan 1st 1941."

Acknowledgements

The books containing this scale drawing form part of a large set of records of "the privately owned railway companies (and their predecessors) taken over by the British Transport Commission under the Transport Act 1947". This digitised version of the drawing was uploaded to the SCRCA Project database under licence, courtesy of The National Archives. (Catalogue Reference RAIL 491/1158, "Settle to Carlisle, bridge, tunnel and culvert drawings: Bridges nos: 48 - 94, Horton in Ribblesdale to Dent - bridge 66, no6.") The license was purchased by - and is held by - Mark R. Harvey.

Review and text by Mark R. Harvey (© Mark R. Harvey, 2020).