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