Impact of Increasing Roadway Construction Standards on Life-Cycle Costs of Local Residential Streets

With increasing damage due to the combination of increasing traffic load applications, adverse climate, and increasing frequency of trench cutting and patching associated with utility work, residential streets are requiring more frequent, extensive, and costly maintenance and rehabilitation (M&R) to maintain adequate levels of serviceability during pavement design life. Increased cost of M&R and eventual reconstruction are an added burden on already limited city budgets. To rectify this situation, city managers and engineers are looking at enhancing current structural design standards for residential streets to increase their load-carrying capacity. With an increase in load-carrying capacity, it is hoped that frequency of M&R will be reduced and the design life of such pavements will be extended. However, adopting a higher design standard has significant cost implications. The question then becomes, Will the expected increase in initial cost be offset by the significant decrease in M&R costs and corresponding increase in pavement life that will delay eventual reconstruction? The Minnesota Department of Transportation (DOT), on behalf of the Local Road Research Board, initiated a study to evaluate the impact of enhancing residential street pavement design standards to accommodate greater axle loads on life-cycle costs. The primary focus was to compare the life-cycle costs of residential streets designed using Minnesota DOT's 5- to 7-ton and 9- to 10-ton design standards. The study concluded that life-cycle cost for the 5- to 7-ton and 9- to 10-ton design standards was not significantly different at the 95% significance level.