Breary Bank Viaduct by Tony Wright
Construction of Breary Bank Viaduct,
For the Masham and Colsterdale Railway.
Introduction;The Masham and Colsterdale Railway runs in an established small suburban garden built on three tiers, an un-interesting small flat oval exists which is fine for small manual loco’s but to make the line more interesting and test steam drivers skills a adventurous extension is under way.
Photo 1
The viaduct is built on concrete piers these are cast in a steel split mould into which 6mm stainless steel studs inserted prior to casting. The concrete mix is 1 part cement, 2 parts sharp sand (the grittier to better), 1 part pea gravel and ½ part black cement dye. The mix is made fairly slack and poured into the mould and very well tamped down to ensure no air bubbles. After a day the mould is split and the pier is scrubbed with a stiff brush and water to remove the finings revealing the gravel, this produces a millstone grit look.
Photo 2
The hole for the pier is dug and lined with hard-core, the pier is then suspended on a RFS tray in the correct position and correct height. The hole is back filled with concrete and well tamped and a final check on position is made.
Photo 3
This is the support bracket for the spans and it sits over the pier studs, the vertical channels hold the spans horizontally in position and the studs laterally.
Photo 4
The spans are cut to length from channel so as to fit between the pier studs. The 10mm spacer’s studs are adjusted to ensure the channel fits over the support bracket channel uprights. Each span is individually made and must be clearly marked for position and orientation, this needs to be visible after painting.
Photo 5
This shows clearly how the spans are held by the support bracket. A nut and washer sit below the support bracket and a cut down penny washer sits on top of the span ends and held by a nut. Adjusting the nuts gives final level and super elevation on the curves.
Photo 6
Here spans one and two are completed with wing brackets and handrail stanchions, the other spans are in situ.
Photo 7
Completed span with handrails and timbers fitted (these are super glue in place prior to through drilling and bolting with 2mm stainless fasteners). The paint system is acid etch primer, black matt enamel and aged iron textured paint, this resembles the micaceous iron oxide paint used on ferrous bridges.
Photo 8
The completed viaduct, the track is Tenmille bull-head rail in plastic chairs. The line of the track was marked out after the spans were located in position this allowed for the curve necessary on the span ends. A template was then used to drill the holes for the chairs. The bridge number sign is from the Otley branch at Arthington Junction.
