BAGBER BRIDGE near Sturminster Newton 1850 HEW 893 St764 157 (Not visited)
This modest-looking 31 foot cast iron beam bridge actually incorporates an interesting feature to alleviate the tensile stress on the girders. Wrought iron tie bars 1 ½ inches in diameter beneath the cast iron girders act to supplement their support as well as to counter the horizontal thrust of the segmental arched ribs of the girders which have a segmental arch rib ( six inches dep and 2 ½ inches thick) incorporated in their web. It is a form of pre-stressing and was also used in the Portland Dockyard No. 6 Boathouse. R.A. Otter points out that this was a very early form of “pre-stressing”. The designer was W. Dawes of the Coalbrookdale Co.