ABSTRACT
This chapter discusses several key issues of track drainage and the effectiveness of various commercially available geosynthetics for enhancing track drainage. The primary purpose of track drainage is to remove water from the substructure as fast as possible and maintain the load-bearing stratum relatively dry. To design an adequate and satisfactory drainage system, it is imperative to first examine the subsurface conditions, and ground water and climatic conditions. Subsurface explorations must be carried out to characterise subgrade soils including type, layering, and drainage properties. Geosynthetics may be classified into two major groups: geotextiles and geomembranes. Geosynthetics generally minimise the track settlement by restricting lateral movement (through transferring lateral loads from ballast to geosynthetics by shear). The tests were carried out using the large-scale cylindrical triaxial equipment. The equipment was further modified to measure the excess pore water pressure at different locations inside the specimen.
