models evaluate managerial recourse, and this provides an opportunity to fx problems if worse-case scenarios occur.
Another class of OR model, Markov decision process (MDP), attempts to link facility condition and optimal long-term maintenance strategy. MDP models are used for management of networks of facility systems and components (such as pavements and bridges). The application of MDP models in facility asset management is limited, in that, for example, facility condition may result from different deterioration processes and require different remedial actions. Deterioration processes and required remedial actions are difficult to define in a model.
Simulation Models. Simulation models are used to analyze the results of what-if scenarios and can be used in conjunction with OR models. Although much research is needed for simulation (deterministic and probabilistic) modeling with regard to facility maintenance and repair funding and consequence analysis (pertaining to outcomes), the U.S. Army Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL) has developed the deterministic Integrated Multiyear Prioritization and Analysis Tool (IMPACT) simulation model.6 The IMPACT model simulates the annual fiscal cycle of work planning and execution and displays building, system, and component condition indexes up to 10 years into the future. The model, in part, sets priorities for maintenance and repair work and their assumptions and assigns funding on the basis of such variables as policies, standards, and budgets.
Proprietary Models. The private sector has long been active in facility-asset management and has collected large amounts of facility data. Some companies have used the data to develop asset management models. Generally, the models purport to predict condition and budgets, and outcomes related to both. However, such models are proprietary, so little about how they work, or about their assumptions, robustness, and accuracy, is publically known or peer-reviewed.
6Information available at http://www.cecer.army.mil/td/tips/product/details.cfm?ID=738.