Given the increasing demand for trains to carry heavier loads, current Australian ballasted rail networks require a significant amount of upgrading. Railroad ballast is an unbounded granular material that displaces laterally when subjected to repeated train loading. During track operations, ballast deteriorates due to progressive breakage and the infiltration of fine particles or mud-pumping from the underneath layers (e.g., capping, subgrade), which decreases the shear strength, impedes track drainage and increases the deformation of ballasted tracks. Rail track substructures can be reinforced by geosynthetics to reduce lateral displacements and optimise overall track performance. This paper presents the current state-of-the-art knowledge of rail track geomechanics based on research conducted at the University of Wollongong, including essential topics related to laboratory tests, computational modelling and field investigations undertaken to examine the improved performance of ballast by the use of geosynthetics. Full-scale monitoring of instrumented tracks supported by RailCorp and Australian Rail Track Corporation (ARTC) has been carried out to obtain data (i.e. measure the in-situ stresses and deformation of ballast embankments) that will reliably verify track performance as well as calibrate and validate introduced numerical simulations. This paper focuses on primary research and development of new design and construction concepts to enhance track performance using geosynthetics, whilst highlighting examples of innovations from theory to practice. These results provide promising approaches that can be incorporated into existing track design routines to cater for future high speed trains and heavier hauls.