The　modern　high-speed　railway　usually　consists　of　track　structure,　subgrade　and　soil　layers.　The　existence　of　track　structure　and　subgrade　can　both　improve　the　critical　speed　of　railway　especially　when　the　railway　is　built　on　soft　soil　layers.　However,　the　role　that　the　track　structure　played　hasn’t　been　distinguished　from　subgrade.　Therefore,　further　research　is　needed　to　investigate　the　difference　of　the　critical　speeds　in　ballasted　and　ballastless　track.　In　this　paper,　two　different　types　of　track　structures,　ballasted　and　ballastless　track,　are　built　on　the　same　subgrade-soil　model　using　two-and-half-dimensional　(2.5　D)　finite　element　method　to　calculate　the　vibrations　induced　by　the　same　high-speed　trains.　The　rails,　rail　pads　and　ballast　layer　in　ballasted　track　and　rails,　rail　pads,　slab,　CA　layer,　concrete　base　in　ballastless　track　are　modelled　as　Euler–Bernoulli　beams　resting　on　the　subgrade.　The　subgrade　and　soil　layers　are　modelled　by　the　2.5D　finite　elements.　The　critical　speeds　in　ballasted　track　and　ballastless　track　are　compared　to　reveal　the　consequence　of　track　structure.　It　reveals　that　the　critical　speed　in　ballastless　track　is　equal　or　greater　than　that　in　ballasted　track.　When　the　subgrade　has　enough　stiffness,　the　critical　speeds　in　both　ballasted　track　and　ballastless　track　can　be　the　same.　It　can　be　concluded　that　the　subgrade　is　more　dominant　than　track　structure　in　deciding　the　critical　speed　of　railway.　©　2022,　The　Author(s),　under　exclusive　license　to　Springer　Nature　Switzerland　AG.