Talk:Box girder bridge

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Surely the box girder's ancestor (or one of them) is the tubular bridge. Stephenson's Britannic Bridge completed in 1850 is often called the world's first box girder bridge. Jooler 13:11, 8 May 2006 (UTC)[reply]

Ancestor perhaps, but these early tubular bridges are not box girder bridges and it's wrong to describe them as such. There are two significant differences:

A tubular bridge places the carriageway inside the tube. That much is unimportant, but it implies (importantly) that the "box" or "tube" is quite tall. This spaces the top and bottom webs further apart, making the overall girder stiffer.
The early tubular bridges used a cellular girder (cf. William Fairbairn) in their upper and lower webs. This also improves stiffness.

So early tubular bridges are actually quite complex. Box girders are a simplification of their manufacturing costs, and this over-simplification without a full understanding of their behaviour under load led to the failures. Andy Dingley (talk) 17:56, 4 August 2009 (UTC)[reply]

What about Torksey viaduct (built 1849)?

Wikipedia's Tubular bridge page, states that: 'This is now considered as the first box girder bridge.' 86.12.208.62 (talk) 00:49, 3 August 2024 (UTC)[reply]

Yes, Torksey is the first box girder bridge.It was built in the short interval between Stephenson's Conwy and Britannia tubular bridges. It also had delays during construction as its novel design wasn't accepted by the Railway Inspectorate (Board of Trade at that time). There's a complex story in that, worth adding to the article. Part of it is that Torksey was designed by John Fowler whom today we regard as one of the pantheon of great Victorian engineers. However at the time he was a youngster, trying to make his name, and only just accepted to the major engineering societies. Few inspectors would tell Stephenson that they didn't trust his bridge design, let alone the great Fairbairn, but Fowler was a young whippersnapper who didn't have such status. Then Stephenson suffered the Dee Bridge disaster. The investigator there was Lintorn Simmons, who was shortly afterwards the inspector on Fowler's new bridge design. So Simmons was in no mood to have any radical new bridge design foisted upon him, and he resisted as strongly as he could. Andy Dingley (talk) 02:20, 3 August 2024 (UTC)[reply]