The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations) and observed variations in hardness and microstructure. It is shown that the hardness of an “in-service” wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing). The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets.

A cab-based track monitoring system has been developed which makes use of the existing on-board GSM-R cab radio present in the majority of trains operating in the UK. With the addition of a low-cost sensor, type, location and severity of the track defects are reported using the system. The system improves safety and network performance by efficiently directing maintenance crews to the location of defects, minimising time spent on maintenance and inspection. Initially, vehicle dynamic simulation was used to test the feasibility of the system for defect monitoring and to develop compensation factors for vehicle type and operating speed. Novel on-board signal processing techniques are also presented through comparison of vibration response from sites with known defects and outputs from Network Rail’s (NR) New Measurement Train (NMT). Good agreement was reported for track faults in relation to vertical and lateral alignment and dip faults. Statistically, good agreement has been demonstrated, suggesting that the data acquired could be used to provide an indication of track quality thereby improving network performance, reducing rough ride and leading to improved passenger comfort. Improvements in the measured and statistical correlation are anticipated through the use, of multi-train / multi-journey and machine learning methods..

This paper investigates the wear rate and pattern for wheels turned with thin flanges using economic tyre turning. Economic tyre turning refers to the process of turning wheels to a profile that has the same tread shape but a thinner flange than the design case profile, allowing less material to be removed from the wheel diameter during re-profiling. Modern wheel lathes are typically capable of turning such profiles but the GB railway group standards do not currently permit their use. The paper demonstrates how the wheel profile damage model (WPDM) can be used, with a good degree of accuracy, to predict both the magnitude of wheel wear and the worn profile shape of the design and economic tyre turning re-profiled wheels for service mileages exceeding 100,000 miles. The WPDM simulations were run for two typical electric multiple units (one suburban and one intercity train fleet) and a two-axle freight wagon. Additionally, it discusses the calibration methodology used to adjust the wear coefficients contained within the Archard wear model to improve the accuracy of the WPDM simulation results for specific routes and vehicle types. Furthermore, this paper presents the findings of a trial of economic tyre turning on a fleet of intercity trains. The analysis is extended to predict the effect of using economic tyre turning on rail rolling contact fatigue for typical routes and operating conditions using a series of vehicle dynamic simulations. The analysis considers new 56E1 and 60E2 rails together with a selection of worn wheel. The research provides valuable evidence to support a future change to the standards which will allow train operators/maintainers to implement economic tyre turning policies.

The maintenance and renewal activities of wheelsets account for a large proportion of the whole-life costs for railway rolling stock. These activities are influenced by a large number of factors including depot constraints, wheel surface damage, fleet availability and vehicle design. If these factors are not managed efficiently it can have significant implications on a vehicle’s service provision, track damage, environmental and whole-life costs. Therefore, the development of an effective wheelset management tool will support the optimisation of maintenance and renewal regimes, thereby increasing wheelset life and reducing costs. Further development of the Vehicle Track Interaction Strategic Model has enhanced the rolling stock modelling capabilities of the tool through the development of the Wheelset Management Model (WMM). This model aims to assist in the strategic planning of wheelset maintenance and renewal activities and thereby allowing users to examine the benefits and cost impact of a range of different scenarios to optimise wheelset management strategies. This paper describes the capabilities of the WMM and illustrates how the model can be used to optimise a fleet’s maintenance strategy through the application of a realistic industry case study. The implications of different wheelset maintenance regimes on wheelset life and costs were examined. Finally, the paper presents how the tools can be used to investigate whole-system costs and demonstrate the impact of wheelset maintenance on track costs.