USCS and the USDA Soil Classification System: Development of a Mapping Scheme

Abstract : The U.S. Department of Agriculture (USDA) soil classification system is relatively simple to apply while the Unified Soil Classification System (USCS) is more complex. As a result, the USDA system, or a similar method, is more commonly used. However, unless taking direct measurements, the USCS classification is needed to determine soil strength. There is no direct relationship between these soil classification systems, and moving from one scheme to another can be tedious and is inexact. Currently, individual researchers, engineers, and soil scientists have their own mapping to move from one system to another, which can lead to confusion when sharing work with others. A consensus method for mapping from one classification scheme to another would avoid this. By analyzing the mappings from six data sets containing thousands of samples, we form such a consensus.