Low-Level Concrete Bridge Over the Mary River, Maryborough, Queensland.” by ALFREDBARTON BRADY, M
246 BRADY ON MARYBOROUGH CONCRETE BRIDGE. [Selected (Paper No. 3184.) ‘‘ Low-Level Concrete Bridge over the Mary River, Maryborough, Queensland.” By ALFREDBARTON BRADY, M. Inst. C.E. THE old high-level timber bridge, 1,456 feetin length, erected across theMary River, Naryborough, in 1874, having been partially destroyed bythe abnormal floods which occurred in February, 1893, thus cutting off the means of communication by road between Maryborough and Tinana and the important gold- field of Bympie, it was decided by the Queensland Government and the Maryborough Bridge Board to construct a low-level bridge of a permanent character on the downstream side of the old struc- ture, and to take down, and remove from the site, the standing portion of the old timber bridge, the traffic meanwhile being pro- vided for by a steam ferry. Alow-level bridge, it was considered, wouldserve allpur- poses and would be much safer during floods. It had been amply demonstrated during floods in various parts of the colony that floating logs, trees, and heavy masses of debris are not usually carrieddownstream in any considerable quantityuntil bridges built at low levels have become entirely submerged, and then all drift timber can float harmlessly over them. A low-level bridge would also necessarily be so much shorter between the banks-in thisinstance 843 feet shorter-and the cost of maintaining the roadway and the bridge generally would be correspondingly reduced. After some timespent in making surveys, taking soundings and borings, and preparing and considering various schemes, the Author’s design for a concrete bridge was finally approved by the Bridge Board and the Government; tenders were invited and a contract was let in September, 1894.
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