A life-cycle cost model for noise barrier walls was developed based on survey data and field observations. The model includes all costs required to construct the noise barriers and uses sen:ice-life estimates based on field observations and surveys. The results indicate that earth berms represent the lowest cost alternative and metal barriers with absorptive panels are the most expensive. The life-cycle costs of wood, concrete, Carsonite, and Durisol fall within a relatively narrow range near $323/m(2) ($30/ft(2)), approximately twice the cost of earth berms. A sensitivity analysis of the model indicated that the two most important variables are initial construction cost and service life. The difficulty in obtaining data is the primary reason many state transportation departments do not use life-cycle cost analysis to select noise barrier materials. Because of the importance of the costs associated with the frequency of maintenance and replacement, and the difficulty in obtaining reliable data, life-cycle cost analysis may not be practical to use as the sole criterion for selecting noise barrier materials. However, it can serve as an additional tool to rank the cost effectiveness of alternative materials and designs.
