Safe-life approaches and empirically based NDT procedures are still dominating in axle design and maintenance. However, new calculation methods and statistical approaches have gained an increased attention. In this article, axles of a standard freight wheelset (22.5 tonne axle load) and of two heavy haul wheelsets (25 and 31 tonne axle loads), all made from EA1N material, are used for illustration and comparison of design methods using a safe-life approach and a crack-propagation/defect-tolerance approach. The safe-life approach used in design standards has in general been found successful, especially for lowstrength materials like EAIN. For high-strength materials in high-speed applications some problems have been encountered. Uncertainties in loading, material parameters, corrosion, surface damage, etc., are complications in the design as well as for defining operational and maintenance practices. Crack propagation at the fillet between the axle body and the wheelseat has been studied. It is found that the calculated residual life is quite sensitive to initial crack depth, initial crack length, shrink-/press-fit interference, and axle load. There is also a significant difference in residual lives between the axles, although they have almost identical design stresses according to EN 13103. It should be noted that the present study only considers alternating bending (not rotating bending), which may have some influence. The three axles studied have shown excellent operational performance in real service, one type for more than 30 years. The crack propagation analysis does not indicate that the axles are over-dimensioned. Thus, the safe-life approach has worked well in the present cases. The overall conclusion is that crack-propagation studies can be successfully used for estimating the influence of different parameters and for supporting decisions regarding NDT at maintenance of axles. Although they are currently not well suited to fully replace safe-life calculation standards, they can contribute with additional support to such calculations