Since the textural classification is based on the percentages of sand, silt, and clay size making up the soil. Such a classification is more suitable for describing coarse-grained soil.

Highway research board classification system is also known as public road administration (PRA) system.

To use the textural classification chart, for a given percentage of three constituents forming a soil, lines are drawn parallel to three sides of the equilateral triangle.

Terms such as gravel, sand, silt, and clay are used to indicate grain sizes. These terms are used only as a designation of particle size.

In the particle soil classification system, soils are arranged to the grain size.

Soil classification of composite soils exclusively based on the particle size distribution is known as textural classification.

Based on particle size, soil can be classified as

Triangular classification of U.S. public road administration is a commonly used system for textural classification.

Group index of soil usually varies by

The purpose of soil classification is to arrange various types of soils in to groups according to their engineering or agricultural properties.