Determination of the weighting factors of criteria influencing highway flooding using Multi Criteria Analysis based on an Analytic Hierarchy Process

Flooding is one of the major natural disasters affecting millions of people. Thailand is also frequently faced with this type of disaster. In particular, the 2011 mega flood in Central Thailand, which inundated highways, severely contributed to the failure of national economies and increased the risk to life. Lessons learned from such an extreme event encouraged flood monitoring and warning, two basic elements of sound mitigation. Weighting factors for each cause of highway flooding are considered as essential information for classifying the degree of highway flood hazard and to enable flood monitoring and flood warning in hazardous areas. We have investigated the causes of highway flooding and have found that the three major factors that influence highway flooding are the characteristics of the highway, the hydrology and the land topography. The importance of each cause of highway flooding in the whole country was assessed by weighting these three major factors using a Multi Criteria Analysis (MCA) based on the Analytic Hierarchy Process (AHP). The MCA, based on the AHP, was selected due to its ’ being a structured technique for organizing and analyzing complex decisions based on mathematics and psychology. According to the results of MCA, the highway, the hydrological and the topographic characteristics of the land were weighted as 35, 35 and 30 percent, respectively, regards to influencing or causing highway floods. These weighting factors are estimated values indicating the relative importance o