Floodways are typically used in situations where it is impractical to provide a bridge or culvert solution. Despite public campaigns on the risk of crossing a flooded floodway, fatalities continue to occur. Research has indicated that the vast majority of designated floodways are not to the required design and hydraulic standards, have inappropriate signage, and depth gauges can provide misleading information. This often leads to drivers under-estimating the risk of crossing a flooded floodway. The main findings of the study are: * Many of the approximately 20 000 floodways found mainly on low-volume roads across Australia and New Zealand, have not been constructed with appropriate geometric/drainage elements and many lack the signage required by Australian Standards. * Lack of reliable records on floodway incidents in the standard crash databases makes it impossible to determine the complete characteristics of incidents and the scope of the safety problem. * The lack of measures such as warning signs, water depth gauges and associated guideposts to delineate a flooded roadway places drivers at a greater risk in deciding when to cross. The research also indicates the need to not only rely on current static warning signs but to make greater use of active warning systems for drivers to make appropriate crossing decisions. * Public advice currently provided not to cross flooded roadways is not seen as realistic, practical or appropriate, hence the need for better measures to promote greater safety. * Depth gauges provided at floodways are of limited value and may mislead drivers in crossing a flooded roadway. A more appropriate indicator is one that is based on combined effect of water depth and flow velocity on a ‘design’ vehicle type (i.e. car, 4WD, truck, etc.). * There are a number of new devices and technologies including automatic warning systems that could be applied to better inform motorists when not to cross a floodway. These devices can provide real-time information to alert drivers of floodway conditions by triggering flashing beacons, message signs and/or lowering of barriers when water depth and flow velocity reach pre-set values. They are, however, costly and are only suitable for critical sites and on high-volume roads. * Implementation of improved measures at floodways should consider a management strategy that assesses risk, appropriate treatments, and the resources needed to bring about improvements over time. * It is recommended that further studies be undertaken at a later date to review legal appraisal of advice for drivers on floodways and new technologies which may assist drivers in making an informed decision about crossing safely. (Author/publisher)
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