Fatigue　represents　a　critical　condition　for　infrastructure　subjected　to　repeated　cyclic　loads,　such　as　steel　railway　bridges.　The　literature　offers　several　methods　to　estimate　fatigue　life,　consisting　of　three　main　phases:　cycle　counting,　fatigue　damage　criterion,　and　damage　accumulation　criterion.　Applying　S-N　curves　might　not　be　conservative　in　the　case　of　railway　bridges　subjected　to　traffic　because　the　stress-time　history　is　complex　and　cannot　be　reduced　to　a　sinusoidal　history.　Additionally,　the　presence　of　a　multiaxial　stress　state　must　be　considered.　Therefore,　this　work　compares　eight　multiaxial　fatigue　damage　criteria　for　evaluating　fatigue　life　in　a　scenario　between　high　and　low-cycle　fatigue.　Specifically,　the　authors　considered　four　low-　cycle　fatigue　criteria,　namely　Smith-Watson-Topper　(SWT),　Kandil,　Brown　and　Miller　(KBM),　Glinka,　Fatemi　and　Socie　(FS),　and　four　high-cycle　fatigue　criteria,　Crossland,　Basquin　and　the　methods　recommended　by　Eurocode　3　and　British　Standard.　The　rainflow　counting　method　in　ASTM　E1049-85　(2011)　and　Miner＇s　rule　for　damage　accumulation　were　used.　The　Polcevera　railway　steel　bridge　was　selected　as　a　case　study.　A　3D　numerical　model　was　developed　for　this　purpose　using　Midas　Civil　software,　taking　into　account　the　material　non-linearity　of　the　bridge＇s　elements.　Once　the　area　with　the　highest　stress　concentration　was　identified,　a　detailed　analysis　was　conducted　to　estimate　the　stress　and　strain　time　histories　induced　by　train　traffic.　A　sensitivity　analysis　was　conducted　after　critically　comparing　the　eight　methods　for　predicting　fatigue　life　to　assess　the　impact　of　traffic　parameters,　train　velocity,　axle　load,　and　convoy　length　on　fatigue　life.　It　has　been　found　that　the　criteria　considering　axial　stress　tend　to　overestimate　the　number　of　fatigue　cycles　to　failure　compared　to　the　criteria,　including　the　effect　of　shear　stress　components.