Causeways - Risk Mitigation through Renewal Upgrade and Emergency Response

Abstract

Research shows that the major cause of flood fatalities is people driving into flood waters. Causeways, by nature, present high flood hazard as most of the flow is over the road where vehicles travel. Moreton Bay Regional Council is taking action to minimise the risks at these locations with a range of measures targeted as fit for purpose for the location, traffic and identified hazard. In the Moreton Bay Region, causeways are generally located crossing significant waterways in rural and rural residential areas, where a bridge solution would be prohibitively expensive in consideration of the low traffic volumes (very high cost for limited benefit). Increasingly, as the population in these areas grow the expectation of improved flood free access is increasingly high. The Council Causeway Program provides for capital projects to undertake planning, design and delivery of renewals and upgrades. The objective of the individual projects is to improve the trafficability, safety and resilience of the causeway crossing while at the same time addressing environmental (predominantly fish passage) issues. In order to populate the Causeway Program, a regional prioritisation approach was developed with determining factors including alternative route availability, road hierarchy, frequency of closure, available condition data, future development implications and road upgrade projects. Other measures to promote safety during flood events have been implemented to support flood response including automated phone calls alerting road closure operations to inspect locations where the road status can be related to flood warning gauge levels; low cost flooded road sensors set up with automated alerting; flooded road warning systems and development of flood information tools to support flood response. This paper provides an overview of the approaches MBRC is taking to minimise the risks associated with causeways which by nature presents a high hazard at the road where vehicles travel. The paper discusses the regional prioritisation process for the upgrade and renewal program as well as measures implemented to support flood response operations in closing of roads.