21 September 2014

Yorkshire Bridges: 6. Ribblehead Viaduct

TripAdvisor reckons this imposing railway viaduct is in the top 30 out of over 400 visitor attractions in North Yorkshire. That's some distinction for an elderly railway bridge situated far from significant towns and cities amidst the windswept moors.

Ribblehead Viaduct is the largest and probably the most famous structure on the Settle to Carlisle Railway. As with the rest of the line, it was built to the design of John Sydney Crossley.

The bridge comprises 24 brick arches, with stone spandrel walls, supported on 6-foot thick stone-faced piers. Every sixth pier is 18-foot thick, and acts as a "bookend" which would in theory allow part of the viaduct to stand up even if the arches on the other side were to collapse. This is a common feature on large viaducts of this type.

The photographs show bands of black and red brickwork. I believe the red brick has been re-cased as part of extensive repair works undertaken in the early 1990s. Some of these repairs are illustrated on the Settle and Carlisle Railway Trust website.

Several pattress plates can be seen which anchor tie bars across the arch barrels. These have been installed at some point to restrain outward movement of the spandrel walls. Photos from the repair works show longitudinal cracks in the arch barrels along the lines of the spandrels, associated with this movement.

New drainage downpipes can be seen on the piers, and the top level of these corresponds to the backing material that sits above the piers and between each of the arch barrels. This backing is essential to the stability of the arches.

Projecting stones are visible at height on each of the piers which will have originally been used to support the temporary timber centering upon which each arch was erected.

The bridge's main attraction is its setting amidst pretty bleak moorland.

Further information:

17 September 2014

Lancashire Bridges: 7. Greyhound Bridge

This is the last of the bridges on the River Lune that I visited earlier this year - continuing further downstream you would come to the Lune Millennium Bridge, but I have featured that previously.

The first bridge at the site of the Greyhound Bridge was a timber viaduct, built in 1849 to carry rail traffic to Morecambe. This was replaced in the 1860s with a more durable wrought iron structure, and then replaced again in 1911 with the riveted steel bridge that remains there today.

In the 1960s, the rail line was closed as part of the Beeching rail cuts, and in 1971-2 the bridge was converted to carry a highway and reopened. I can't readily think of other examples where this has happened. The diagram below shows how the bridge was altered:

The bridge's steel girders rest on cross-braced steel tubular caissons. The reinforced concrete highway deck was propped off the existing bridge crossframes with a series of steel stools, and cantilevers considerably beyond the original deck width. The works were designed by C. S. Allot and Son, later part of Allot and Lomax, and now absorbed (via Babtie) into the Jacobs empire.

Further information:

15 September 2014

Lancashire Bridges: 6. Skerton Bridge

Skerton Bridge was built in 1787 to a design by Thomas Harrison. It makes for an interesting comparison with the Lune Aqueduct, completed in 1796.

Harrison's bridge was a replacement for the first bridge over the River Lune at Lancaster, a wooden bridge which dated as far back as the 13th century. This bridge had been rebuilt and repaired on numerous occasions, and in the 18th century was part-demolished to prevent Scottish rebels from crossing the river.

Harrison's new bridge was built for £14,000, and consisted of five elliptical stone arches, later extended with a further span across a railway at its southern end. It was notable for its level highway. Although it predates Rennie's Lune Aqueduct by nearly a decade, it is by far the more elegant of the two bridges.

The bridge is Listed Grade II*, and I particulary enjoy the Listing description:
"5 gracefully shallow semi-elliptical arches with archbands, and above the semicircular cutwaters between them are aediculed niches with mutuled pediments and engaged Tuscan columns. The whole is crossed by a cornice with mutules, and a balustraded parapet in which plain panels alternate with groups of 6 balusters."

Further information:

11 September 2014

Lancashire Bridges: 5. Lune Aqueduct

Lune Aqueduct has been referred to as a "wonder" and a "masterpiece". Engineering Timelines calls it "architecturally the finest aqueduct in north west England". Completed in 1796, it carries the Lancaster Canal above the River Lune. It was designed by John Rennie and is now Listed Grade I.

It is certainly an impressive structure, with five massive semi-circular arches springing from huge stone piers. However, compared with Telford's beautiful Pontcysyllte Aqueduct, completed ten years later, it appears squat, even lumpen.

The bridge is monumental rather than elegant. The large semi-circular arches are one cause of this, as are the wide stone piers. It gives the impression it could stand forever, although of course it has required extensive repairs in the recent past.

Further information:

02 September 2014

Lancashire Bridges: 4. Denny Beck Bridge

This bridge is something of mystery: I've been able to find nothing of any significance about it either in my library or on the internet. I don't know when it was built, or why, or who designed or built it. If you have answers, please post in the comments!

It is a single-lane highway bridge, operated without traffic lights. It consists of two metal lattice girders at the edges of the deck, each with two planes of lattice web. The bottom chord of each truss, and any crossbeams, are encased within a concrete deck slab.

The superstructure is supported from a series of cross-braced metal trestle piers. These have inclined legs on the upstream side to protect them against impact from river-borne debris.

The metalwork is riveted, which dates the original bridge construction to 1960 or so at the very latest, and probably much earlier. A bridge of broadly similar construction at Heatherslaw Mill in Northumberland dates to the 1870s.

Update 4th September 2014:

The comments to this post offer further information on this bridge, and see also pages 206 and 207 of http://www.drakkar.co.uk/ch13.pdf.

Further information:

31 August 2014

Lancashire Bridges: 3. Penny Bridge, Caton

This bridge spans the River Lune midway between the two former railway bridges in my last post.

Built in 1883, it comprises three elliptical sandstone arches. The roadway is level, with straight balustraded stone parapets either side.

The road originally crossed the river here at a ford, until a privately funded bridge was built in 1805. Like the present bridge, this had three elliptical stone arches. A penny was charged as the toll for the use of the bridge. As of 1880, the bridge was badly deteriorating, and the County Council took over the bridge, building the new one for £8,500.

The bridge was designed by the Lancashire County surveyor, with local architects E.G. Paley and Hubert Austin, and is now Listed Grade II. The builders were Benton and Woodiwiss, a Derby-based firm, who were also extensively involved in railway construction.

This bridge just leaves me with questions: why is the roadway level, when a curved alignment would have looked much better? Why are the parapets solid over the piers and only balustraded over short lengths over the arches?

Further information:

28 August 2014

Lancashire Bridges: 2. Crook O' Lune Railway Bridges

I'm featuring a few bridges on the River Lune, working downstream towards the see. Most of these are readily accessible from a cycle trail, the Lune Millennium Cycleway, which runs along a disused railway line between Caton and Lancaster, indeed the first two bridges, at Crook O' Lune, carry the cycle trail itself.

The two bridges were built around 1880 and carried the Midland Railway (formerly the "Little" North Western Railway) across a long U-shaped bend in the river. The railway line was closed to passengers in 1966, and dismantled in the 1970s. Both bridges are Grade II Listed.

I have seen the bridge design credited to Edmund Sharpe, but there seems to be a discrepancy with dates. English Heritage list the bridges as being in the 1880s, but Sharpe's involvement with the railway line dates from when it was first constructed in the late 1840s. If anyone knows anything more, please post in the comments.

Both bridges are essentially identical, consisting of a number of wrought iron arch spans supported on sandstone masonry piers and abutments. The choice of material may explain the discrepancy in dates. The shape of the arches seems to indicate cast iron, but closer examination shows riveted construction. Perhaps cast iron spans were replaced in wrought iron?

Whatever the case may be, these are fine bridges.

The east bridge was extensively refurbished in 2013 at a cost of between £1m and £1.5m.

Update 4th September 2014:

Correspondent Bill Hosfield provides the following further information:
"The anomalies about the dates of these two bridges is no doubt due to the following facts. These twin bridges were originally built to carry what became known as the "Little North Western Railway" over the Lune, and this officially opened to traffic on the 17th of November, 1849. The connecting of Edmund Sharpe's name with these two bridges is due to the fact that this Lancaster architect was responsible not only for designing the railway but for being the contractor for constructing a section of the line, and finally taking over the running of the company.
"The second date ascribed to these bridges is due to the fact that when built this railway had only a single track but in 1888/9 a second track was added and so to accommodate this the bridges had to be reconstructed. This necessitated the widening the orginal stone piers and replacing what had been timber beams with the present metal arches. From a detailed study of the masonry work it is possible to see where the new work was bonded to the old, and also to see some of the sockets in the stonework that received the ends of the struts that supported the timber beams".
Further information: