| This research addresses the large-scale group fleet replacement problem with multiple vehicle types of multiple units, under budget and demand constraints. Past research in group fleet replacement is limited and has focused on one vehicle type, with multiples units and constraints. Many studies in fleet replacement have also dealt with single replacement, with single units, and with no constraints. The objective of this research is to find the methodology to solve the general large-scale group fleet replacement problem.; A multi-phase methodology based on the grouping concept is presented and is integrated with optimization techniques. The vehicles are grouped according to various technology parameters. A two-level hierarchical replacement process, focusing on inter-group, and intra-group analysis, is developed and the resulting models are solved using integer programming. Finally, a case study using the Oregon Department of Transportation records is examined.; The replacement model presented can incorporate complex variations in the large-scale group fleet replacement problem. It is flexible and can be used in wide variety of replacement problems. Used appropriately, the results from this methodology can result in reduced fleet replacement costs and operation costs. |
