BS EN 13231-5:2018 pdf download

BS EN 13231-5:2018 pdf download

BS EN 13231-5:2018 pdf download.Railway applications – Track – Acceptance of works
4 Basics
4.1 Technical Introduction
The complexity ofvehicle – track interaction generates high stresses at the rail- wheel contact, the severity of which is governed by local track characteristics, vehicle type and other operational conditions. The repeated application of these stresses results in the development of fatigue cracks usually referred to as RCF manifested as head checks, gauge corner cracking, or squats. Although rail metallurgy offers a key mitigation measure against such fatigue degradation, there are no rail steels currently in use that could fully withstand the repeated application of such contact stresses. Furthermore the majority of rails in track today, despite their adequate but lower fatigue resistance, have an appreciable residual  life span, which makes it more economic to maintain them in an appropriate manner to extend their life rather than to change them. Management of rail profile and condition is therefore a prerequisite for safe and cost effective operation of railways. Predictable work – at least in a medium time horizon一organized in a strategic way needs to be defined to extract the maximum benefit from existing technologies and to guide the industry for future development. However, it is essential to ensure that the chosen approach provides enough flexibility to adapt to changing situations in both senses: increased requirements for maintenance due to higher loads and dynamic forces, reduced requirements for maintenance due to lower loads (improved vehicle characteristics) and better performing rails (reduced fatigue development). The life expectancy of a rail is influenced by its interactions with the other parts of the train – track system. The faster and more frequent train services, higher axle loads and new generations of vehicles with greater primary yaw stiffness have significantly increased the critical track forces that promote more rapid degradation of the rail (and wheel) leading to more frequent and costly maintenance interventions and even rail renewal. Significant research into rail metallurgy has resulted in the development of rail steels with much higher resistance to wear and RCF. Nevertheless rail maintenance by reprofiling is an essential requirement for efficient and safe functioning of railway track. The combination of rail grade selection and maintenance strategy considering local track and traffic characteristics ensures effective control of any kind of rail surface defects.