Long-Term Maintenance of Culvert Networks

Infrastructure systems in the United States are in need of urgent maintenance and rehabilitations. Preservation of culvert networks, a major component of U.S. infrastructure systems, at an acceptable level of serviceability subject to the stringent yearly maintenance and rehabilitation (M&R) budgets is a major challenge for culvert network owners and managers. Decision makers are required to develop an optimum financial plan to minimize the total cost of maintenance and rehabilitation for different expected improvements of the culvert network performance during a given planning horizon. This manuscript presents a discussion on budget planning for maintenance and rehabilitation scheduling and optimization of a culvert network. Any maintenance and rehabilitation expenditure should be justified such that net increase in the asset value should be more than the cost of rehabilitation, where the net worth of an asset should be based on performance rather than on book value. Government standards require owners to maintain or improve the overall condition state of their infrastructure systems with substantial annual investment. In this paper, three methods were proposed to compute the long-term annual investments for culvert networks. They are modified worst first method, network optimization approach, and estimation by the maximum deterioration rate. The performance of a 15-culvert system was simulated using the above methods. Based on the simulation results, the modified worst first method is computationally intensive but provides the optimum budget. The method using maximum deterioration rate provides the lower bound value and should be used as the absolute lowest value that should be allocated. The optimization method uses computer programming and provides an upper bound value for small networks. It is anticipated that for large culvert networks the network optimization approach can be used to provide reasonable long-term annual budgets. Out of the three methods, the modified worst first method provided a minimum long-term annual budget of $9,000 consistent with the government requirements.