ENHANCEMENTS TO THE NETWORK OPTIMIZATION SYSTEM

The network optimization system (NOS) used by the Kansas and Alaska departments of transportation addressed the question, What are the minimum budget requirements necessary to maintain prescribed performance standards? Each road category, with its unique performance models, was solved individually with its own preselected performance standards. The reverse question, What maximum performance standards can be maintained for a fixed budget?, had to be solved by an iterative approach. In a constrained funding environment, the more important reverse question required considerable time and computer resources. The resulting solution may not be optimal, because several combinations of performance standards can meet the fixed budget. The methodology of NOS was enhanced to perform as a linked model. Once an initial feasible solution is obtained for the network using the original version of the NOS, an initial percentage budget is specified for each category as a starting point. A linked model, long-term solution is obtained before running the linked-model, short-term model. Both solutions work by creating a master matrix that is revised for each iteration of the linked model until an optimal solution is found. The solution includes optimal performance standards for each road category at a specified total budget. Initial runs of the model result in improved pavement condition when optimized statewide at the budget level recommended by the optimization of individual road categories.