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 Canal Masonry and brick bridges.
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| When canals were built they cut
across estates, farmlands and existing roads. The canal company
was required in the Acts of Parliament that authorised the canal
to ensure that no one was inconvenienced. Hence large numbers of
bridges were required, often doing no more than linking two
fields, as in the simple brick accommodation bridge on the
Llangollen Canal on the left. Much grander structures were
erected when country estates were crossed and the permission of
the landowners had to be courted, as with the high masonry
bridge on the Shropshire Union Canal on the right. |
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Canal Timber and cast iron bridges.
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| Wooden bridges were cheaper to build than masonry or brick
bridges. They were used for footbridges at locks and sometimes
for accommodation bridges like this ladder bridge on the Oxford
Canal, left. The walkway is a single timber beam which has
sagged considerably over the years. Cast iron bridges were used,
especially around Birmingham. These bridges were built to a
common elegant design. They were also used to take the towpath
over the old loops when the North Oxford canal was shortened.
(Photo right Tony Lewery) |
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Canal Turnover bridges and split footbridges.
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| Sometimes the towpath had to move from one side of the canal to
the other. Turnover bridges allowed the towing horse to cross
the canal without the tow line getting caught up in the bridge.
The smooth curves of these bridges often make them most
attractive structures, as the turnover bridge on the Shropshire
Union Canal on the left. Split bridges were used around locks to
enable the towing line to pass through the bridge when the
towpath did not go under the bridge, as on the right on the
Staffordshire & Worcestershire Canal. (Photos Tony Lewery) |
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Canal
Aqueducts
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| Aqueducts were not much liked by the early
canal builders because the weight of the water and the clay
needed to keep the canal trough watertight required a very
substantial structure to support it. Masonry aqueducts like the
one on the Lancaster Canal on the left bear witness to this
stature. Compare this with the Bearsley Aqueduct on the
Stratford Canal on the right which has a cast iron trough
supported on tall slim masonry pillars. The cast iron contains
the water and has sufficient rigidity without the great bulk of
the masonry aqueduct. (Photo left Tony Lewery) |
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Canal Swing and
canal lift bridges
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| Movable bridges were usually cheaper to build than fixed bridges
because they didn't require the same heavy foundations and
structure. Canals which were short of construction money often
used lift bridges, as on the Oxford Canal and on the Llangollen
Canal on the right. Lift bridges were counter-weighted and
usually operated manually or by using a windlass. Swing bridges
are common on a number of canals such as the Gloucester &
Sharpness Canal where river craft did not have to lower their
masts to pass and on the Leeds & Liverpool Canal where many have
now been converted to electrical operation. |
