Budget Optimization of Concrete Bridge Decks under Performance-Based Contract Settings

Abstract

Growing needs for maintenance, repair, and replacement (MRR) of existing transportation infrastructure signifies the importance of new and innovative contracting strategies. Among the emerging contracting methods in the area of transportation infrastructure management is long-term performance-based maintenance contracts, also known as performance-based contracting (PBC). To date, PBC has not been implemented in the area of bridge infrastructure maintenance management due to uncertainties in the bridge deterioration process and challenges in modeling performance. The main objective of this research is to develop short- and long-term optimal MRR plans for bridge decks under PBC settings. This objective necessitates the development of a performance model to define the current condition of bridges and predict their future deterioration rates. The performance model is essential to select appropriate MRR actions that enable planning these actions and estimating the needed budget. The research introduces an integrated condition as a key performance indicator of the bridge component (i.e., bridge deck). Further, an associated level of service (LOS) threshold is defined. The output of this research is a decision support model for selecting optimal rehabilitation strategies while maintaining a defined performance LOS and budget constraints. A modified genetic algorithm (GA) is developed to perform the optimization of resources under the defined LOS and is coded in MATLAB version R2014a software to perform the needed analysis. The decision support model is evaluated with a real case study for a bridge located in Quebec, Canada. Sensitivity analysis is performed to evaluate the impacts of the decision variables against the cost. For instance, the analysis proved that improving the LOS by 18% requires an increase of an MRR budget by about 51%. Research findings concluded that integrating the PBC approach into the decision-making process offers better results in long-term plans. The focus of this study has mainly been on bridge decks. Future work may target expanding to the other bridge components and additional related assets.