Constraint-based clustering model for determining contract packages of bridge maintenance inspection

When a number of bridges are to be maintained yearly, contract engineers need to package certain bridges based upon the specified conditions. Traditional contract packaging is performed subjectively and manually. The purpose of this paper is to develop an objective and automatic decision-making process for contract packaging. Contract Packaging Technique (CPT), which is derived from k-prototypes, can determine appropriate contract packages by considering the inherent conditions of the infrastructure to be maintained. It can simultaneously handle user-specified constraints and mixed data types such as bridge locations, bridge types, bridge construction materials and maintenance costs. Validation was performed in this study to illustrate that the CPT can effectively divide a huge bridge maintenance plan into several appropriate contract units.