The problem of identifying the optimal maintenance work for a given road section has been tackled by two fundamentally different approaches: option evaluation approach and optimization approach. Option evaluation approach models such as RTIM, HERS and HDM-4 predict life cycle costs for maintenance options exogenously specified by the analyst and therefore can be used to identify the option with the least cost among those tested. Recently, the feasibility of using gradient methods with option evaluation systems has been demonstrated. Gradient search methods, however, are known to be handicapped by their likelihood to be trapped in local optima and it is not always possible to prove that total transport cost function is unimodal with respect to the variables defining maintenance strategies. Contrary to the option evaluation approach, the optimization approach does not entail exogenously specified alternatives. To facilitate the analysis, however, this approach requires substantial simplifications in terms of both the relationships and the constraints describing the system. This paper presents a unique methodology in which option evaluation systems and optimisation models are combined to complement these deficiencies. The methodology is demonstrated through a case study that shows how the two approaches are used in tandem to search for the optimal maintenance strategy. (a) For the covering entry of this conference, please see ITRD abstract no. 0612AR242E.
Abstract