SWCC of Unsaturated Tropical Weathered Residual Soils Appropriate for a Range of Index Properties Using Pressure Plate Apparatus. Tropical weathered residual soils are used as construction material for a different type of works in an unsaturated state. Several researchers have studied these soils to establish the theoretical framework for their conditions. The techniques of prediction of the behavior of unsaturated soils are constantly under review. In geotechnical engineering practice soil water characteristics curve (SWCC) is a constitutive relationship useful for interpreting the response of unsaturated soils more reasonably. Various in-situ and/or laboratory tests can be used to measure directly the discrete points of the SWCC. Such direct measurements are, however, costly and time-consuming due to high standards for equipment and procedural control and limits in testing apparatus. Therefore, in this study; index property and pressure plate tests were first conducted for the representative number of soil samples excavated (depth < 2.0 m) along the stretch of the road under construction around Bahir Dar called Gonbat. These are to develop the design SWCC representative for the tropical weathered residual soil in the region. Moreover, the fitting performance of existing SWCC fitting models to the measured suction versus water content data points was studied. Therefore, from the experimental and curve-fitting model comparison studies; it is concluded that: the index property test results and classification soils indicate that the entire soil in the region is either sand with gravel or/and gravel with sand soils dominated, and are evaluated very good for a sub-base (selected fill) material substitute. The pressure plate test results from the two specimens tested are closely reproducible, and it is concluded that the model developed by van Genuchten (1980) and Fredlund-Xing (1994) lead a comparably fit best for the measured drying front SWCC data points for both types of soils. The Fredlund-Xing (1994) model, however, allows for the best-fit of unimodal soil data from an extremely low suction to an upper limiting suction value of 1,000,000 kPa and are suggested to fit the limited discrete data points measured in laboratory and determine the required design parameters and further unsaturated soil property functions from the SWCC curve for these unsaturated soils. From the developed SWCC, the air entry value, residual suction initial and residual water content computed from both fitting models for sandy soils are relatively larger than for gravel soils. The air-entry and residual suction/value determined from Fredlund-Xing (1994) SWCC fitting model from the initial drying curve for both types of soils/sandy and gravel soils are larger than the values computed by van Genuchten (1980) SWCC fitting model.