Tunnels, Bridges, Lifts and Inclines

On December 5, 2010 · 10 Comments

I’d love to spend a few weeks on a narrowboat traveling through the canals and inland waterways of Great Britain. There are literally thousands of miles of publicly-accessible routes available with much of it interconnected into a single system, allowing one to experience the countryside at four miles per hour.

This article isn’t so much about the canal network itself. Other websites such as British Waterways, Scottish Canals and the Inland Waterways Association already provide all the information one might need. Rather, this is about some of the unusual engineering features found along these waterways.

While I’m sure I’d be completely content as I puttered through the British countryside, I’d certainly point a course towards the extremes and the oddities. Water doesn’t necessarily flow where man may want it to go. It has to be channeled, corralled and coaxed to form a suitable transportation network. Engineers and designers came up with some rather ingenious solutions from the late 18th Century through the middle of the 19th Century in those early years of the industrial revolution.

Tunnels

Does a hillside block the intended watercourse? No problem. Build a tunnel.



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I had a difficult time finding a visible canal tunnel entrance from the images available on Google Street View. In general, canals are dug from the surrounding landscape so they sink below eye level. They tend to have right-of-ways on either side that becomes naturally protected spaces for trees and other vegetation. It’s easy to spot a canal running through the countryside by searching for a tell-tale line of trees. Getting a clear shot of a canal as it enters a tunnel from Street View imagery however is a completely different story.

The one shown here is known at the Dudley Tunnel and it remains submerged for about 1.75 miles. This forms part of the Dudley Canal in the West Midlands and it was used originally to transport limestone. This entrance happens to be located right by the Dudley Canal Trust which offers underground boat trips into the tunnels and over to the limestone caverns.


Bridges (Aqueducts)

Imagine the importance of these inland waterways of the 19th Century especially in the days before the ubiquitous railroad. Certainly greater tonnage could be floated through the countryside than pulled by horse or ox across abysmally rutted roads and muddy paths. I suppose I shouldn’t be surprised to see canals that resemble modern road networks, as that’s the purpose they served during their prominence.

Obstacles in the way? Bridges are handy.



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Construction engineers could design bridges — or aqueducts — at the intersection of canals where elevations differed. I found this example not far from Dudley as I searched for canal tunnels. I couldn’t get a clear image of the tunnel (open the map and it can be found immediately to the south-southwest) but I did find this nice bridge. Here the Netherton Tunnel Branch Canal passes beneath the Old Birmingham Canal Navigations (BCN) Main Line at Tividale Aqueduct.

Exceptional aqueducts existed at valley crossings. Designers sometimes chose to cut a path directly above the valley rather than step a canal down to the valley floor and then step it back up with a system of locks. An aqueduct is more difficult from an engineering standpoint but transportation time savings would be considerable.



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Pontcysyllte Aqueduct in Wales is particularly dramatic, carrying the Llangollen Canal over a valley formed by the River Dee. This cast iron structure spans nearly a quarter of a mile while carrying boats 125 feet above the valley floor. Google Street View captured this well. I can see four boats crossing in succession. The though of carrying what is essentially a river across this gap is truly remarkable. Perhaps that is why this 1805 achievement is a UNESCO World Heritage Site:

Situated in north-eastern Wales, the 18 kilometre long Pontcysyllte Aqueduct and Canal is a feat of civil engineering of the Industrial Revolution, completed in the early years of the 19th century. Covering a difficult geographical setting, the building of the canal required substantial, bold civil engineering solutions, especially as it was built without using locks. The aqueduct is a pioneering masterpiece of engineering and monumental metal architecture, conceived by the celebrated civil engineer Thomas Telford. The use of both cast and wrought iron in the aqueduct enabled the construction of arches that were light and strong, producing an overall effect that is both monumental and elegant…


Lifts and Wheels

I have nothing against canal locks. I rather enjoy them as a matter of fact, both modern and antique. However they’re simply too common. Tunnels and Aqueducts are great too, however, let’s get to some even more unusual structures that can be experienced on the inland waterways of Britain.


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SOURCE: Flickr (deadmanjones), via Creative Commons, Attribution-Non Commercial License

Don’t have enough room for a lock? Build a lift.

I couldn’t find a decent angle on the maps websites so I’ve borrowed an image from Flickr. This shows the Anderton Boat Lift in Cheshire (see map). A boat enters the lift. Counterweights composed of water-filled caissons move vessels between the River Weaver (up) and the Trent & Mersey Canal (down). The elevation difference between the two waterways is about fifty feet.

Only one other working boat lift exists in Britain and it’s of recent vintage: the Falkirk Wheel in Scotland (see map).



SOURCE: YouTube (praatafrikaanz)

I’d love to visit someday but I’ll have to satisfy my curiosity with YouTube for now. It’s also a lot easier to let the video demonstrate how this thing works instead of trying to explain it. The Falkirk Wheel is a rotating lift rather than an elevator-style lift. It is used to connect the Forth and Clyde Canal with the Union Canal, replacing eleven traditional locks over a nearly eighty foot elevation difference.

The Falkirk Wheel arrived more than a century after the heyday of industrial revolution canal building. It opened in 2002. This recent vintage seems somewhat mystifying since many other options are available for cargo transport. It seems to exist primarily for tourism and recreation.


Inclined Planes

Are other options available? Why yes, there’s always the inclined plane.



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Great Britain no longer has any functioning inclined planes along its inland waterways as far as I could ascertain. However I found evidence of one that existed in the early 20th Century at the Foxton Locks. These were found in Leicestershire along the Grand Union Canal. The satellite image shows the ruins of the old inclined plane with functional locks on the left.

It’s an odd concept about halfway between a lift and a lock, with characteristics of both. Like a lock, it conforms to the contours of the landscape. Like a lift, it uses counterbalances to create a single continuous motion. Wikipedia has a nice photograph of an inclined plane in action on the Marne-Rhine Canal in northeastern France. It looks really strange.

The inclined plane at Foxton Locks reduced travel time from 75 minutes to 12 minutes but there wasn’t sufficient barge traffic to make it viable economically. Restoration, however, is underway with the increased interest in recreational canal boating. Britain may have an inclined plane once again.

Are any of the readers of the Twelve Mile Circle familiar with these or similar structures? Please share your findings in the comments.

On December 5, 2010 · 10 Comments

10 Responses to “Tunnels, Bridges, Lifts and Inclines”

  1. Alan Twelve says:

    My first thought reading this was of the Falkirk Wheel, but you got there ahead of me…

    So, have a tunnel instead. The Regents Canal in north London passes under Islington and the western end of the tunnel is clearly visible in Streetview from Caledonian Road.

    http://bit.ly/eOQnix



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    Unfortunately, the eastern end of the tunnel is pretty much obscured by trees, but is just about visible here:

    http://bit.ly/i8hPUY

    There’s a nice webpage about the Islington Tunnel (and London’s other two canal tunnels) here:

    http://www.londoncanals.co.uk/ltnl/ltnl01.html

    One little point of trivia. If anyone’s read the Iain Banks novel Walking On Glass, the final scene of the book, by the canal, is set at the western end of the Islington Tunnel.

  2. Alger says:

    In the US canal building craze of the 1830s there were all kinds of work-arounds for places that you couldn’t force water to run uphill. A well-known example is the Pennsylvania Canal portage rails, which were invented so that Pennsylvania could compete with the Erie Canal.

    The Allegheny Mountains forced all kinds of odd curves and detours onto the path, but at several places the grades became so severe that they needed to load the canal boats onto bogies and winch them up the mountain to be dropped back into the canal which continued on the other side.

    http://www.jaha.org/edu/flood/why/img/canal_gallery/pages/allegheny_portage_rr_plane_.html

    Today the state maintains a park at the site of one of these inclines, just outside of Lilly.



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  3. wangi says:

    The Falkirk Wheel replaces the original stair of 11 locks (inclined plane?) which linked the Union with the Forth and Clyde Canal. Another interesting feature on the Union is the tunnel at Hallglen: “As William Forbes refused to allow the canal to pass within sight of his property, Callendar House, this tunnel, the only canal tunnel in Scotland, had to be constructed under Prospect Hill. The tunnel, which is 690 yards in length and has a towpath running right through it” (although not the only tunnel now; as another was built at the same time as the Wheel, under the Antonine Wall no less)

    http://canmore.rcahms.gov.uk/en/site/46771/details/falkirk+union+canal+canal+tunnel/ (with photos)

  4. FS says:

    I visited the Falkirk Wheel a few years back-it’s quite a sight.

  5. Katy says:

    There’s also a place in the Netherlands where one can drive under a canal, though it’s more of a 20th century construction:



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    Another view: http://www.panoramio.com/photo/221986

  6. Thias says:

    Hey!
    The french inclined plane you mention is about 10 miles from my home!

    • Thias, have you visited the incline? Is it truly as odd as it looks?

      • Thias says:

        I did visit it, although I never really understood all the mediatic ‘buzz’ around it. It’s a little strange, but when I visited it – and used it, because you can board a boat and use the plan – my main reaction was: “meh”.

  7. Guy says:

    Hi, great blog! I discovered it through your comment on Strange Maps.

    There is an inclined plane in Ronquières, Belgium, see this Wikipedia article. And here is a list with another few.

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