In terms of the track, the life cycle of a rail begins when it is installed there. Nowadays, a variety of optimized rail grades can significantly increase service life depending on the operating conditions. By selecting the right rail grade, the foundation for the maximum service life can be laid before installation. To install rails in the track, they must first be transported to the worksite, unloaded, and installed. The joining technology (e.g. flash-butt welding) is an especially important part of the installation. The rail joint should not fail prematurely; it must have the same service life (and properties) as the rails. Once they are installed in the track, the newly laid rails must be treated. This involves the decarburized layer (also known as the rolling skin – an effect of rail production) being removed mainly through grinding, eliminating various superficial injuries (from transport and installation) and, if necessary, adjusting the rail profile. This creates an ideal, flawless rail condition from the start.

Condition recording using complete data

The actual life cycle begins when the first train travels over the track. Depending on the loads, rail damage occurs after some time in the form of plastic deformation, wear, rolling contact fatigue (e.g. cracks), and thermal damage. Fatigue defects can also occur inside the rail. This damage shortens the service life of the rails and requires appropriate optimization. Before suitable measures can be taken, the condition of the rails must be recorded at regular intervals. This includes measuring the transverse and longitudinal profiles, detecting surface conditions (cracks, surface effects, rolling marks) using video analysis, determining the depth of surface damage (e.g. using magnetic flux leakage testing or eddy current), and recording potential internal defects using ultrasonic testing. In addition, track and vehicle data from other sources (e.g. track maintenance machines, general vehicle data, GIS data, etc.) should also be taken into account and linked. Intelligent analysis and user-friendly presentation of the data is particularly important here, as only then is it possible to derive appropriate measures to maximize the rail’s life (data management).

Measures for optimizing the rail life cycle

Figure 2 shows the possible measures for system optimization. Adapted rail and wheel profiles reduce the stresses in the wheel-rail contact, an optimal track position reduces the dynamic forces acting on rails, and friction management (lubrication for the sides, tread conditioning, and rail cleaning) decreases wear and cracking. The aim of all these measures is to delay rail damage. The only measure that not only delays existing damage, but also removes it, is rail treatment. Due to demographic change, railway operating companies often do not (or no longer) have sufficient resources to optimize the system themselves, which is why specialist service providers must be used.

Measure – plan – maintain – measure

Grinding or milling technology is used for actual rail treatment. Rail grinding is particularly suitable for preventive to medium corrective strategies, while the advantages of rail milling can be put to use in corrective or regenerative strategies. There are also technologies with oscillating grinding stones or sliding grinding stones, which are primarily used for preventive strategies in urban areas. Circumferential grinding with actively or passively driven grinding stones is also sometimes used as a preventive measure. After the rails have been treated, the measuring technology (machine-integrated or as a manual system) mentioned above is used for quality inspection. These measurements also serve as a starting point for planning future maintenance measures. Subsequently, the steps measure – plan – maintain – measure are carried out in a continuous sequence (optimization cycle). A system audit is also carried out regularly on the basis of these in-depth analyses in order to identify various changes at an early stage and adapt measures and strategies if necessary. When the wear limit (or damage limit) of the rails is reached, they are removed and recycled. This final step marks the end of their life cycle.

End-to-end solutions for rails

Together with our partner companies, Plasser & Theurer offers a range of products and services that cover almost the entire life cycle of the rail (Figure 3).

At the end of 2023, a joint initiative was launched to take a closer look at the topic of "the rail". The aim is to identify the current and future potential in this group (completed), promote cooperation within the group of companies (in progress), and also coordinate future activities.

Due to the extensive group portfolio and the considerable market potential, the future will see a greater focus on the end-to-end view of the rail life cycle. Once again, the aim is to increase train capacity and reduce maintenance costs.