The prestressed concrete railway sleepers (or railroad ties), which are installed in railway track systems as the crosstie beam support, are designed to carry and transfer the wheel loads from the rails to the ground. It is well known that railway tracks are subject to impact loading conditions, which are attributable to the train operations with either wheel or rail abnormalities such as flat wheels, dipped rails, etc. These loads are of very high magnitude but short duration. In many cases, it has been reported from the fields that concrete sleepers are lacking of support due to mud pumping or excessive but localised track settlement, so-called ‘voided sleepers’. This paper presents a numerical study to evaluate dynamic responses of the voided concrete sleepers to impact loading. A simplified finite element model of concrete sleepers was developed and validated against experimental data. The model has then been used to evaluate the effect of voids on the dynamic responses of concrete sleeper to a typical impact loading. The outcome of this study will help engineers to determine the life of assets and to investigate the failure mode of concrete sleepers and associated track components in actual ballasted tracks. It also gives better insight into the dynamic behaviour of voided concrete railway sleepers.