Bilston Viaduct

Bilston Viaduct, northern end


12 February 2012

Loanhead, Midlothian

NT 28068 64926; 55.87209°N, 3.15113°W


Close to the site of the former Bilston Glen Colliery, the lattice-girder viaduct spans the valley of Bilston Burn to the south of Loanhead. It formed part of the Edinburgh, Loanhead and Roslin Railway, which opened in 1874. The original bridge built for the line was composed of six lattice-truss spans, but this was replaced in 1892 by the present structure composed of two 60 ft side spans and a 330 ft main span, 140 ft above the valley floor.

The line ran from Millerhill to Glencorse, and as well as serving various mines and the army barracks on the outskirts of Penicuik, the line also operated a passenger service. The railway became the Glencorse branch line of the North British Railway in 1877, the latter in turn becoming part of the London and North Eastern Railway in 1923.

The passenger service was terminated in 1933 and the line was closed for freight past Roslin in 1959 and in 1969 a further section was closed with the colliery becoming the end of the line. Following a £1.5m renovation by the Edinburgh Green Belt Trust, the viaduct was opened to pedestrians in 1999.

Bilston Viaduct (Royal Commission on the Ancient and Historical Monuments of Scotland)

Cast-iron roller and rocker bearing, replaced when the viaduct was renovated in 1999

Interpretive plaque on the bearing

A web of rail lines linked the mines of Midlothian to cities and factories. This viaduct carried the Glencorse branch line, which took coal and ironstone from mines in Penicuik, Roslin, Bilston, Loanhead and Gilmerton. It was also a busy passenger line, especially for excursions to Roslin.

The viaduct is the longest span in Scotland to use this lattice-work design. The separate pieces were made in Glasgow and put together here like a huge piece of flat-pack furniture, held together by thousands of rivets. Each rivet had to be heated to nearly white hot, then driven in and fastened.

There had been an earlier bridge across the glen, built when the line opened in 1874. This first viaduct failed because of ground movements caused by the mines. The rail company may also have lost faith in its design: the engineer had been Sir Thomas Bouch, who also built the infamous Tay Bridge.

Beneath this plaque is one of the massive iron bearings that carried the weight of the viaduct: some 1,500 tonnes. This is about the same weight as 120 double-decker buses! The bearings have to let the whole structure move as well as supporting it, because bridges stretch in the sun.

Metal expands in the heat, so on a hot summer day the viaduct is about 60mm (2½ inches) longer than in the middle of winter. At the bottom of this bearing you can see the rollers that allowed the bridge to move; the great bolt in the middle let the lattice of iron girders twist slightly as well.

After one hundred years the bearings had rusted solid and the bridge’s movement had begun to crack the stonework. New bearings had to be fitted, but the rest of the viaduct was in good condition. During the repair work of 1999, not one of the rivets had to be replaced.

 — Interpretive bronze plaque


Looking south across the replacement concrete bridge deck

Lattice-work parapet

Southern end of the viaduct


Viaduct 140 ft above the Bilston Burn valley


7 thoughts on “Bilston Viaduct

  1. I was going to say which one I liked the best, and then another one kept popping up as my favorite. 🙂 The composition in the first one is spot on. Love it. The X photo too, the shapes on the plaque are great, and of course, I love that water drop on the hand rail, as I’ve played with photographing that too.

    Great set of photos, Graham!

  2. Great shots. I’m surprised this is still standing, when I walked over it about 20 years ago it looked as if it was falling to bits…glad to see it’s had some TLC! Obviously it was sounder than it looked, reading your description. Anyway, all the shots are great, but my fave is the last one…tells a story for me.

    • Thanks Iain. Yes, it sounds like the main structure was sound and that the major issues were with the deck and the bearings. It now forms part of a rather pleasant network of paths around the area of the old colliery. By the way, there is now also a large housing estate (Copper Wood) stretching almost up to the viaduct that never use to be there when I lived there.

  3. If you look at each end of bridge on the stonework next to iron frame work you will find small holes at the top these were for brass measuring gauges about six inches long for measuring how much of the bridge moved during hot weather alas these were broken off in the early sixties. The spare bearings 2 were lying underneath on the loanhead side for many years. I was brought up in Traprain Terrace Loanhead

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