With the advent of high speed trains, large cyclic stresses are exerted on ballasted rail tracks which in turn cause excessive settlements and lateral deformations of granular materials leading to frequent maintenance of track. The use of planar reinforcement is well established in rail environment to address such aspects. Recent studies have shown that geocell can provide much better lateral confinement to infill soil compared to planar reinforcement. However, a limited number of researches have been performed to examine the performance of reinforced sub-ballast under cyclic loading in railway environment. In this study, the large-scale prismoidal triaxial apparatus have been employed to investigate the performance of reinforced and unreinforced sub-ballast during cyclic loading. A series of drained tests were carried out to examine the behaviour of unreinforced and geocell reinforced sub-ballast subjected to cyclic loading exerted by train passes. The laboratory experiments were carried out in plane strain condition at very low confining pressure to simulate railway environment. Effects of varying apparent confining pressure (σ′3), frequency (f) and number of load cycles (N) were also studied.