Economics of upgrading gravel roads to Otta seal surface

Maintenance of low volume roads especially gravel roads is costly, and millions of funding annually are spent for aggregate replacement alone. Otta seal, compared to other bituminous surface treatments (BSTs) for low volume roads that require high-quality materials and specialized expertise, can be constructed using cheaper local aggregates and accessible equipment. However, only three states have reported Otta seal constructions and performance in the US. In this study, an economic analysis was conducted to compare the cost of maintaining a gravel road to the cost of upgrading an existing gravel road to a double Otta seal surface. This analysis was conducted at three levels: deterministic life-cycle cost analysis (LCCA), a stochastic Monte Carlo simulation-based LCCA, and a traffic based economic analysis. A generic one-mile rural road in Midwest was considered as a case study location. Although, according to the analysis conducted in this paper, an upgrade to Otta seal investment might be justified by maintenance savings, resorting to only such justification cannot warrant investment in most cases. The upgrade from gravel road to Otta seal, or any other BSTs, might be justified in terms of enhancing safety for road users and also encouraging economic development beneficial to local areas.