Improvement Recommendations for Unsealed Gravel Roads

Abstract

A method was developed to recommend improvements for unsealed earth and gravel roads that are not up to the standard expected for their functional class. As part of a pilot asset management program carried out by the Wyoming Technology Transfer Center, roads were rated for several distresses, including corrugations–washboards, rutting, potholes, loose aggregate, drainage, dust, and overall condition by using a visual survey method. These ratings were used to calculate a surfacing serviceability index (SSI) for each road section. This SSI was compared with the minimum acceptable SSI for the section's functional class. When the section's SSI was below this threshold value, improvement tasks were selected from a decision matrix, and the most expensive task was recommended to address the section's inadequate surface condition. This process allows an agency to present its elected officials with a list of roads in their network that need improvement, along with an estimate of the cost of these improvements. The method presented in this paper can be used by agencies with extensive unsealed road networks if they perform a visual survey rating various distresses and they develop a decision matrix based on these distresses to establish appropriate improvements to substandard roads.