NCHRP Report 590 describes the development of methodologies for network- and project-level optimization of multiple, user-specified performance criteria for bridges. Bridge management software modules to implement the methodologies were also developed.  The report details the development of methodologies. The software modules, user’s manual, and demonstration database are provided on an accompanying CD-ROM. The material in this report will be of immediate interest to bridge managers and planners.

Currently available bridge management system (BMS) tools compute an optimal solution based on the objective of least long-term cost.  Bridge managers are finding that their constituents require bridge conditions to be substantially better than a least long-term cost solution would provide. Research was needed to develop a multiple-objective optimization model.

To address this need, two distinct BMS optimization models were developed: a network-level and a bridge-level. The network-level model provides a decision-making tool that optimizes bridge actions for multiple-performance criteria. These performance criteria could be cost, condition, risk, highway bridge replacement and rehabilitation (HBRR) program eligibility, bridge health index, or others. The bridge-level model evaluates the effect of bridge action alternatives on life-cycle cost and other performance criteria for the purpose of selecting projects that are consistent with the network goals.

Both models use the AASHTO BridgeWare database supplemented with additional data as needed. Commonly Recognized (CoRe) Elements data are used for condition assessments. The bridge-level model considers recommendations from the network-level model. In addition, the network model can consider projects selected within the bridge-level model.  These models also can operate independently.  Both models explicitly consider the inherent uncertainties of estimated costs and outcomes. The models are implemented in graphical design software that will help bridge managers visualize the life cycle of individual bridges and bridge inventories.

This research was performed by Purdue University, in West Lafayette, Indiana, and Paul D. Thompson, Consultant. The report fully documents the research leading to the recommended models.