[3] One-sixth scale models, 78 ft long, were built at Fairbairn's Millwall Iron Works and tested with increasing loads.

By this means, although at an experimental cost of thousands of pounds, the design of the cellular girder was refined until it could carry loads of 2.4 times the original capacity.

The "Great Tubular Bridge" over the River Wye, which at that point forms the boundary between Wales and England, is considered one of Brunel's major achievements, despite its appearance.

John Fowler's 1847 tubular girder design for Torksey used tubes that were only 10 foot high and placed the railway deck between them, rather than inside.

[5] Despite this, it was initially rejected after completion by the Board of Trade’s inspector, Captain Lintorn Simmons, and the design was also criticized by the Institution of Civil Engineers.