There are over 1.6 million miles of unpaved roads (53% of all roads) in the United States. In some nations, the road network is predominantly unpaved and generally consists of gravel roads. This 5-hour interactive online course was developed with a major emphasis on the maintenance of gravel roads, including some basic design elements.
Gravel roads are generally the lowest service provided to the traveling public and are usually considered greatly inferior to paved roads. Yet, in many rural regions, the volume of traffic is so low that paving and maintaining a paved road is not economically feasible. In many cases, gravel roads exist to provide a means of getting agricultural products in and out of farm fields, timber out of forests, or as access to remote areas such as campgrounds and lakes. Many gravel roads serve rural residents as well. Many of these roads will remain unpaved due to very low traffic volume and/or lack of funds to adequately improve the subgrade and base before applying pavement layer(s). In some countries, economic constraints mean gravel roads are the only type that can be provided.
The purpose of this course is to provide clear and helpful information for doing a better job of maintaining gravel roads. It is recognized that very little technical help is available to small agencies that are responsible for managing these roads. Gravel maintenance has traditionally been 'more of an art than a science' and very few formal standards exist. This leads to many arguments between grader operators, managers, and motorists over questions such as: What is enough surface crown? What is too much? What causes corrugation? This course contains guidelines to help answer these and other questions about the maintenance of gravel roads.
This course, based upon a federally funded Department of Transportation study, is designed for the benefit of engineers, contractors and related professions who are responsible for designing and maintaining gravel roads. There are over 100 pictures illustrating concepts outlined in the text!
This course includes a multiple-choice quiz at the end of each section. You must have Flash Player Version 7 or higher to view some parts of this course. We also recommend you view this course in Internet Explorer.
At the conclusion of this course, you will understand:
- Proper gravel road cross-section design.
- Routine shaping principles employed by maintenance crews.
- Routine maintenance and rehabiliation techniques used on gravel roads.
- The impacts of a proper road shoulder on gravel roads.
- The uses and limitations of equipment used in the construction and maintenance of gravel roads.
- The causes and solutions for corrugation, whip-off, gravel migration, subgrade failure, parabolic crowns, secondary ditches, and a number of other areas of concern for gravel roads.
Course Level: Fundamental
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