Cumbria Bridges: 12. Devil's Bridge, Kirkby Lonsdale

This is one of several bridges I visited back in May, all around the border between Cumbria and Lancashire, and all of which span over the River Lune.

"It is by far the finest bridge in the north of England", wrote Edwyn Jervoise in 1931. Like the similarly ancient Twizel Bridge (in Northumberland), it is a ribbed arch, a type I always find visually attractive. It is a Scheduled Ancient Monument, and a very handsome structure.

The bridge dates to the 13th or 14th century, and as with many other structures around Europe, it was reputed to have been built by the Devil. An old woman made a deal with the Devil for him to build the bridge in return for the first soul to cross over. She then tricked him by throwing bread across the bridge so that her dog ran over it first. The story is recounted in more detail in George Bernard Wood's book, Bridges in Britain.

There are many variants on this tale for the many so-called Devil's Bridges, suggesting that the poor fellow struggled to learn any lessons from being repeatedly tricked.

Further information:

• Google maps / Bing maps
• Wikipedia
• Engineering Timelines
• Structurae
• English Heritage
• The Ancient Bridges of the North of England (Jervoise, 1931)
• British Bridges (Public Works, Roads and Transport Congress, 1933)
• Bridges in Britain (Wood, 1970)
• Civil Engineering Heritage: Northern England (Rennison, 1996)
• An Encyclopaedia of Britain's Bridges (McFetrich, 2010)

Cumbria Bridges: 11. Bridge House, Ambleside

This bridge is a curiosity more than anything else.

In Bridges in Britain, G Bernard Wood described the bridge as follows: "The tiny bridge-house is a waif of Time, stranded between road and car-park".

It was reportedly built over 300 years ago as an apple store for the nearby Ambleside Hall. It was apparently constructed over Stock Ghyll in order to avoid land taxes.

In 1926, it was purchased and passed to the care of National Trust, who still use it as an information centre and shop.

Further information:

• Google maps / Bing maps
• British Listed Buildings
• Bridges in Britain (Wood, 1970)
• An Encyclopaedia of Britain's Bridges (McFetrich, 2010)
  
  
  
   
  
  

Cumbria Bridges: 10. Trevor Woodburn Bridge

Now, here's a quite remarkable little bridge, which I think is totally unknown beyond its immediate vicinity but which easily deserves to be better publicised.

It lies on a foot and cycle trail connecting Elterwater to Skelwith Bridge, near Ambleside in Cumbria. It spans the River Brathay a short distance upriver from the waterfall, Skelwith Force. The creation of the trail was proposed in 1998 by local man Trevor Woodburn, and the bridge is named after him. It was completed at the end of 2006, and officially opened in July 2007.

The bridge was designed and fabricated by specialist architectural and sculptural metalwork firm Chris Brammall Ltd, who have also been responsible for some highly sculpted bridge parapets at Staveley and Sunderland. It cost £225,000, spanning 20m and weighing 16 tonnes.

The bridge deck consists of metal plate on steel members, while the parapets comprise a series of steel flat posts supporting an oak handrail. According to the designer's website, the geometry of the posts was "inspired by the tectonic pressure patterns in the surrounding rock faces".

The posts each have a slightly different geometry, with a slight indentation in profile developing towards midspan into a pronounced kink. The effect is to create an intriguing sculptural surface which presents an attractive profile from almost any perspective, yet dissolves entirely on a closer view.

The inner and outer surfaces of the parapet are formed from the same geometry yet visually are very different.

I think it's a gorgeous little bridge, and a genuine enhancement to visually and environmentally surroundings.

Further information:

• Google maps / Bing maps

Cumbria Bridges: 9. CKPR Bridge 75, Crozier Holme

Finally, here's the last of this set of disused railway bridges on the Cumbria, Keswick and Penrith railway lines.

Bridge 75 is an upright bowstring truss spanning 101 feet. For this bridge, I have a copy of a bridge record drawing, taken from John Rapley's book (see link at the end of the post). This shows the bridge before any strengthening was added in 1931-3. You can compare this against the photographs to see what was changed.

Of the various upright trusses on the line, this one has the most substantial overhead bracing. Otherwise, it is broadly similar to the others. It can be seen looking down to the river from the adjacent A66 highway bridge.

For anyone who would like to visit these bridges, there are details and directions in the Bowstrings over the Greta leaflet (linked below) and also on the Lake District Miles Without Stiles website. Free parking is available next to Keswick leisure centre, and there's a splendid pub in Threlkeld where weary, hungry or thirsty pontists can rest before returning along the route.

Further information:

• Google maps / Bing maps
• Bowstrings over the Greta (ICE)
• ICE PHEW database
• Forgotten Relics of an Enterprising Age
• Keswick to Penrith Railway Re-opening
• Thomas Bouch: The Builder of the Tay Bridge (Rapley, 2007)

Cumbria Bridges: 8. CKPR Bridge 74

I'm nearing the end of this set of bridges which formerly comprised part of Thomas Bouch's Cockermouth Keswick and Penrith Railway (CKPR) line.

This penultimate bridge is another upright bowstring truss. Unlike the previous examples, Bridges 69 and 71, this one has overhead bracing between the trusses, although so little as to be barely worth having.

The bridge lies a short distance to the east of a lovely, short little railway tunnel. It spans 122 feet and has a pronounced skew. As with most of the other bridges on the line, it was strengthened during its lifetime by the addition of new cross-girders, additional diagonal bracing struts to the top chord of the trusses, and additional vertical stiffening on the face of the arches. You can see clearly in the photographs how much heavier the strengthening members are compared to the original metalwork.

Although the railway line was closed in 1972, and converted to a foot/cycle trail quite recently, there are proposals to reopen the entire line as a railway (not just the Keswick to Threlkeld section forming the trail). These plans are being promoted by an independent group, not by any government body, and I have to say I think the likelihood of it ever happening is somewhere very close to nil.

They argue that the retention of the original railway bridges would make it easier to reinstate a railway line, but from what I saw when I visited, the present cycle and foot trail is extremely popular, and diverting it would be an expensive and possibly unpopular option.

Although the bridges may broadly have the strength to carry local passenger services, they are not in marvellous condition and would require close examination, repair and repainting to be of any use for a new railway line. There are difficult obstacles elsewhere on the route, where the original track formation has not been protected against encroachment, and it seems unlikely to me that there is a business case of sufficient strength to attract the necessary private investment.

Further information:

• Google maps / Bing maps
• Bowstrings over the Greta (ICE)
• ICE PHEW database
• Forgotten Relics of an Enterprising Age
• Keswick to Penrith Railway Re-opening
• Thomas Bouch: The Builder of the Tay Bridge (Rapley, 2007)

Cumbria Bridges: 7. CKPR Bridge 73, Rowsome

This is the last of the "upside-down" bridges as you head east along the Keswick to Threlkeld trail. This one is the shortest span at 80 feet.

Unlike the other two similar structures I've already covered, this bridge has retained small X-frame parapets, giving it quite a different appearance. It's still difficult to imagine the bridge as it must have been when it carried rail traffic however. I assume it had a timber deck with the rails supported on large longitudinal timbers, width the crossbeam outriggers supporting a maintenance footpath.

I was able to get a better view from directly underneath this bridge, showing the plate girder which was added when the bridge was strengthened in 1924-8. I wonder how the load was shared between the new girder and the original bowstring trusses, and suspect the girder did the lion's share of the work after it was introduced.

It's interesting to compare the two side views of the bridge in these photographs. The north face is considerably "greener" than the south, as you might expect. I wonder what the original engineers, Thomas Bouch and colleagues, would think of their structures being left in such a visibly dilapidated state. Perhaps they would just be pleased to see the bridge still in use, nearly 150 years after the railway line was originally built.

Further information

• Google maps / Bing maps
• Bowstrings over the Greta (ICE)
• ICE PHEW database
• Forgotten Relics of an Enterprising Age
• Keswick to Penrith Railway Re-opening
• Thomas Bouch: The Builder of the Tay Bridge (Rapley, 2007)

Cumbria Bridges: 6. CKPR Bridge 71, Brundholme

Bridge 71 is the longest span so far in this series, at 100 feet, and there are a number of details of construction which reflect the greater demands imposed on it by rail traffic.

While the bridge retains the basic layout of the upright bowstring truss found at Bridge 69, the top flange of the "bow" is beefed up here with the addition of a trough-section on the upper face.

The original stabilising struts on the outer face of the truss have additional struts at their midpoint, to reduce their own propensity to buckle.

When the bridge was strengthened in 1929-31, a number of additional crossbeams were added below the deck, and some of these were extended to carry yet more truss-stabilising struts. These have been added at the midpoint of the truss X-bracing, requiring vertical strengthening to the truss at these points, achieved by adding pairs of steel channel-sections at each location. In fact, these were added at the centre-point of every "X", with a hugely adverse impact to whatever aesthetic the bridge may once have had.

Closer examination of the underside of this bridge shows significant deterioration to the under-deck metalwork, as would be expected for this type of bridge, which would have had a timber deck even in its original configuration.

All in all, this is now one of the uglier bridges along the route, largely because of the chaotic jumble of strengthening measures which have been applied.

Further information:

• Google maps / Bing maps
• Bowstrings over the Greta (ICE)
• ICE PHEW database
• Forgotten Relics of an Enterprising Age
• Keswick to Penrith Railway Re-opening
• Thomas Bouch: The Builder of the Tay Bridge (Rapley, 2007)

Cumbria Bridges: 5. CKPR Bridge 69, White Moss

Continuing to head east, the next bridge after Bridge 67, is Bridge 69. I guess Bridge 68 may have been a culvert or a now-gone overline bridge.

This is the first of the "right-way-up" bowstring trusses that I visited on this route. It spans 80 feet, with a slight skew. In many ways it will appear as a mirror-image of the previous two "upside-down" structures, with similar X-bracing in the truss elevations.

One difference is that the "bow", the curved member, consists of two flat vertical plates on the other bridges, whereas here they are topped with a horizontal flange plate. As the bow is in compression on this bridge, the flange is needed to prevent the other plates from buckling sideways. The overall lateral buckling of the truss is prevented by the presence of strut bracing on lateral beams which extend sideways from the deck. There are four of these on each side of the bridge, a slightly different arrangement from some other bridges on the line, as we'll see.

Bowstrings over the Greta indicates that this bridge required little or no strengthening when the railway line was upgraded for heavier trains in the 1920s/30s.

What is particularly evident now that the bridge trusses are seen close up is that little if any refurbishment was carried out when the former railway bridge was re-decked as a trail bridge. There appears to be nothing more than superficial corrosion to the trusses, but I wonder who will find the money to pay for repainting and/or repair as and when the bridges deteriorate further in the future.

Further information:

• Google maps / Bing maps
• Bowstrings over the Greta (ICE)
• ICE PHEW database
• Forgotten Relics of an Enterprising Age
• Keswick to Penrith Railway Re-opening
• Thomas Bouch: The Builder of the Tay Bridge (Rapley, 2007)

Cumbria Bridges: 4. CKPR Bridge 67

Carrying on along the trail from Keswick to Threlkeld, the next bridge after Bridge 66 is ... Bridge 67.

This bridge is of the same basic form, an inverted bowstring truss, with the same X-bracing on the elevation. This one is a single span of 90 feet, with a slight skew. There is a short flat slab span on the approach at the east end of the bridge.

Like Bridge 66, it has been strengthened with the addition of a single plate girder between the trusses, which can be seen more clearly on these photographs. Cross-bracing connects the two trusses below the soffit of the central girder, while towards the ends of the span the trusses are connected directly to the girder with short stubs.

I'll come back to another bridge later on in this set which shows the details even more clearly.

Further information:

• Google maps / Bing maps
• Bowstrings over the Greta (ICE)
• ICE PHEW database
• Forgotten Relics of an Enterprising Age
• Keswick to Penrith Railway Re-opening
• Thomas Bouch: The Builder of the Tay Bridge (Rapley, 2007)

Cumbria Bridges: 3. CKPR Bridge 66

The Cockermouth, Keswick and Penrith railway line (CKPR) was designed by the famous (or infamous) Thomas Bouch, an engineer later to become notorious following the collapse of his Tay Railway Bridge. His bridges on the Keswick to Threlkeld section of line have had a happier fate, with eight splendid metal structures surviving to the present day, some decades after the railway line was closed to traffic.

I didn't have time to visit all eight bridges, but you can read more about them in Paul Dunkerley's Bowstrings over the Greta, which has a useful map, photographs, and further details. I've relied on it extensively in this and the forthcoming posts.

Bridge 66 is the only double-span bridge to survive, and comprises two spans of "inverted" bowstring truss construction, reportedly Bouch's preferred solution for this line, wherever clearance above the River Greta permitted its use. Nonetheless, he apparently only adopted this design for one other bridge, at Penicuik in Scotland.

The spans are of 57 feet and 89 feet, and the bridge originally carried only a single railway track. In recent years, like the others, the bridge has been adapted to carry a foot and cycle trail by replacement of the deck with a new timber walkway.

It is possible to pass over this bridge with no idea of what lies below, and indeed that's precisely what I did when I first cycled over it. However, it's well worth finding a way down to the river bank to see the bridge properly, as this bridge, along with three other inverted bowstrings on the line, is of a very rare type. My travelling companions called them the "upside-down" bridges, but this form is more economical than the conventional "upright" bowstring bridge, as the curved members are placed in tension and less material is therefore required to resist buckling.

The bridge has an interesting combination of robustness and elegance, and this isn't marred by the presence of a single plate girder in between the two trusses. This was added in 1931-32 to enhance its strength. It must have been a very difficult construction operation, although the photo here shows that a very neat slot was cut in the abutment to accommodate the girder bearing.

I wasn't able to get photographs that show this whole bridge clearly, but some of the other bridges on the route will hopefully show a few more details for the form.

Further information:

• Google maps / Bing maps
• Bowstrings over the Greta (ICE)
• ICE PHEW database
• Forgotten Relics of an Enterprising Age
• Keswick to Penrith Railway Re-opening
• Thomas Bouch: The Builder of the Tay Bridge (Rapley, 2007)

Cumbria Bridges: 2. Greta Bridge

I've recently had the chance to visit a few interesting bridges in Cumbria, in the north-west of England, and will spend the next few posts reporting on them. I've previously featured two other Cumbrian bridges, the bridge at Aira Force waterfall, and the remarkable Fisherman's Bridge.

The majority of the bridges I'll feature over the next few posts form a set, as they all either span over or carry a foot / cycle trail running between Keswick and Threlkeld, which was formerly part of the Cockermouth, Keswick and Penrith Railway. This railway line was completed in 1864, primarily to transport minerals although also serving as a passenger line until its closure in 1972.

Greta Bridge is part of this set but also the odd-one-out, as it spans over the former railway line but was built much later, opening in 1977 as part of the A66 highway bypass to Keswick. It was designed by Scott Wilson Kirkpatrick and Partners, and built by Tarmac Construction. Its chief claim to fame is that in 1999, it was voted Britain's "best concrete engineering structure of the century" by members of the Concrete Society. It was claimed to be one of the first bridges to have been designed using finite-element analysis. New Civil Engineer's report on the award stated: "The structure, designed purely by engineers with no architectural input, is renowned for its aesthetic qualities which ensure it blends well with the surrounding Lake District countryside."

Greta Bridge has four spans for a total length of 220m, and carries a dual two-lane carriageway. It is a concrete box girder of varying depth, superelevated to suit the highway curvature. The boxes are trapezoidal in cross-section. It's the lower, inclined part of the webs which give this bridge its unique character, as in combination with the curved soffits to the girders, they create a lovely series of "scalloped" surfaces defining the lower edge of each span. It's rare to see a concrete box girder bridge which is so visually successful.

It isn't only the box girders that provide the charm to this bridge. The concrete piers are rectangular in cross-section, but indented with a series of dished "flutes" on their long faces. These provide some texture to break up what would otherwise be a very large, flat concrete area, they emphasise the verticality of the piers, and the curved profile to the flutes complements the curved elevation of each girder span.

I personally think it's silly to claim that this was the best concrete bridge in Britain of the 20th century, but it's a very charming structure, and certainly an unusually high quality design for its type.

Further information:

• Google maps / Bing maps
• Structurae
• Greta Bridge voted best structure of the century by Concrete Society (NCE, 1999, subscription required)
• Heritage and History

Cumbria Bridges: 1. Fisherman's Bridge, Cumbria

I had been waiting for a chance to visit this bridge for several months, and was glad to finally see it even if the weather was rather dismal. It's easily a favourite amongst the many bridges I've featured here on this blog.

Fisherman's Bridge is remarkable in many ways. It's not a large structure, spanning only 15m, and a mere 0.9m wide, but it's still quite staggering that it was built for the tiny budget of only £18,000.

It sits on private land in the Duddon Valley, in the Lake District, providing access for an occasional angler across the River Duddon. It's almost impossible to spot from the public highway.

Structurally, it is almost absurdly simple, a simply-supported weathering steel box girder, triangular in elevation and in cross-section at mid-span. I think it's fair to say that it's design hasn't been limited by the standard 5kN per square metre load normally used in the UK.

The structural engineer was Rob Nilsson of Price & Myers, while the architect was Ralph Parker of H-o-n-e-y.

Similarly, the balustrades, intermittent steel rods carrying a tubular handrail, comply with none of the usual requirements, being both easy to fall through, and easy to wobble. That's a good thing, I think.

The rods alternate either side of the handrail to provide some stiffness, but also give a first impression that the bridge has been assembled in a haphazard, jumbled manner.

The steps at either end consist of slate slabs set in concrete, and attempt to raise the bridge clear of the river's flood level. However, the video below, made in November 2009, makes clear that it is not quite high enough!


Original on vimeo

That's pretty impressive, especially when you see how the bridge is attached to its supports, with simple, slender vertical plates.

There are some elements of the bridge which appear unfinished, chiefly the way the parapets are painted rather than in exposed weathering steel like the rest of the structure. It's like a piece of rusty old farm machinery which has been dragged to the bottom of the field and dragged across to span the river.

When I first saw a picture of the bridge, I was disappointed by the triangular rather than curved profile, but up close, quibbles dissolve. It's an entirely singular structure, although I am reminded a little of a similarly rusty, non-standard private footbridge in the US.

You can click on any photo for a larger version, and if you're perceptive, you may notice that the parapet rods are all of different lengths. This is visually attractive, but offers an added surprise - the bridge plays music. Striking the rods with a stick plays a specially composed tune, made especially effective because the box girder acts as a resonant cavity.

It's a crying shame that the bridge has received so little attention (although it was shortlisted for a RIBA 350 Award in 2010). I think it's one of the most interesting footbridges to be built in the UK in the last few years, a delightful little haiku in Cor-Ten.