Saturday, 8 October 2011
Most canal bridges are at right angles to the waterway, however, sometimes the bridge has to be built at an angle. Bridge 19 on the Grand Union just north of Napton junction is one such bridge. Here’s the aerial view.
This bridge, like most on the canals, has a brick arch. Skew arches, as they are called, are much more complex than simple bridges. In some skew bridges, the bricks in the arch are laid parallel to the canal. This results in the bricks at the end of the arch being stepped. Most skew bridges, however, are built like bridge 19 with the courses of bricks at right angles to the walls.
The result is that the bricks are laid at an angle to the springers - the point at which the arches spring from the walls, as shown in these photos. I think this means that each course of bricks is curved to follow the curvature of the arch. These skew bridges add another dimension to the beauty of the canals.
There’s more about skew arches on the wikipedia web site at http://en.wikipedia.org/wiki/Skew_arch