Economic impact of bridge damage in a flood event

Bridges are vulnerable road infrastructure in flood events. Different level damage of bridge can be observed after flood events. As lifeline structures, bridge plays an important role in any road network. Bridge structures involve both great construction costs and great economic value to stakeholders. Despite costs for post-disaster clearance and repair of bridge structures, a decrease in the accessibility of bridges would have a significant impact on regional traffic, residents and businesses. Current knowledge still has gap on fully recognizing and understanding economic impacts of bridge damage. In addition, there was a lack of accurate, detailed and sufficient data as well as validated model that could be used to estimate all types of economic impacts. This research would base on a critical review of existing literature to solve two problems of understanding economic impacts of bridge damage:<br><br>What are the economic impacts of bridge damage in flood events? How to categorize these economic impacts systematically?<br><br>How can these economic losses be measured?<br><br>An in-depth understanding of the effects of bridge damage is required in order to develop estimation methods as well as sustainable management and adaptation strategies.<br><br>This research reviews and summarizes current knowledge on consequences that can be caused by bridge damage due to flood events. Each consequence is discussed and analysed. Likewise, this study systematically categorizes different types of potential economic impacts to bridge stakeholders and local councils into direct tangible/intangible and indirect tangible/intangible types.<br><br>In terms of measuring different types of economic impacts, it is still a great challenge due to the present knowledge gap. This research introduces and integrates existing models in different areas to measure economic impacts that are resulted from bridge damages. For the economic losses of bridge damage and recovery, this research discusses damage states, repair quantities, repair methods and repair costs, which provides guides for the stakeholders to predict repair costs and time limits of recovery projects. For the economic losses of bridge accessibility, this research concerns indirect tangible economic impacts, which include the detour of bridge users and the business interruption. In terms of detour costs of bridge users, models prefer to use regional road networks, average local vehicle operating costs, post-disaster traffic conditions and alternative path choice to estimate the costs of the extra traveling and the opportunity costs of the extra traveling time. With regards to business interruption, this research measures business interruption and the decrease of productive capacity due to bridge damage.<br><br>Although most economic losses can be estimated by monetary flow, some types of economic losses need to be measured or interpreted in terms of consumption of social resources after bridge damage. This research also makes efforts to understand these economic impacts, such as the value of a historical bridge, impacts on the labour market change and losing the trust of authority.<br><br>To illustrate the application of integrating models, Kapernicks Bridge, which is located in Queensland and continues to be damaged as a result of floods in the Lockyer Valley region, is introduced as a case study in this research. In this case study, economic impacts that are summarized are discussed and estimated by the integrated model. In this part, estimation focuses on the costs of extra travel and the opportunity costs of extra travel time. This case study makes two main contributions. First of all, models apply regional data and figure out current data and knowledge gaps leading to model validation. Second, this case study can also be used as a guide to help stakeholders estimate their economic losses due to bridge damage after flood events. Therefore, a focused strategy can be made to decrease losses in the most disaster-affected region.<br><br>This research has two main contributions to current knowledge. The first one is its definition of economic impacts of bridge damage in a flood event. The second one is its application of existing knowledge and models to measure the majority of these economic impacts. Future research can focus on understanding the relations between damage states, repair methods, and repair quantities. Also, future research can make a contribution to knowledge of measuring losing trust on authorities