Bioengineering including native vegetation is an ancient method of improving the stability of slopes. In modern railway engineering, this technique is re-captured for increasing the soil stiffness and shear strength of subgrade beneath rail tracks. Currently this practice has become increasingly popular in Australia for stabilising railway corridors built over expansive clays and compressive soft soils. This paper looks at the stabilisation role by suction generated by both the natural vegetation and the artificial vacuum application using the numerical analysis. For demonstrating the role of native vegetation, a mathematical model for the rate of root water uptake was incorporated in the analysis. The soil moisture content distribution and the soil matric suction profile adjacent to the tree were numerically captured based on the general effective stress theory of unsaturated soil. For vacuum application, the equivalent plane strain theory was employed to simulate radial consolidation and artificially applied suction. The performance of both techniques on track constructed on soft formation was discussed and compared in terms of settlement and associated pore pressure.