THE PROBLEM
Population growth, ageing infrastructure, and community expectations for road and rail links to be closed less frequently by flooding, mean that government agencies across Australia are continuing to build new links or upgrade existing links. When upgrading existing links there is usually an expectation to improve upon what came before. Even where the driver is population growth or ageing infrastructure, there is inevitably a desire for increased flood immunity, particularly in rural communities. Further, maintaining road and rail links during floods mitigates the economic damage of flooding by minimising the closure of important commercial links.
Providing new road and rail links across floodplains or raising existing links to improve flood immunity has the potential to adversely impact on properties by blocking and altering flowpaths and concentrating flows. Therefore, careful design by experienced flood engineers is required to find a solution that optimises the mix of bridges and culverts, and the grade level with external impacts.