The capacity demands on the railways will increase in the future, as well as the demands for a robust and available system. The availability of the railway system is dependent on the condition of the infrastructure and the rolling stock. To inspect the rolling stock and to prevent damage to the track due to faulty wheels, infrastructure managers normally install wayside monitoring systems along the track. Such systems indicate, for example, wheels that fall outside the defined safety limits and have to be removed from service to prevent further damage to the track. Due to the nature of many wayside monitoring systems, which only monitor vehicles at definite points along the track, damage may be induced on the track prior to fault detection at the location of the system. Such damage can entail capacity-consuming speed reductions and manual track inspections before the track can be opened for traffic again. The number of wheel defects must therefore be kept to a minimum. In this paper wheel profile parameters measured by a wayside wheel profile measurement system, installed along the Swedish Iron Ore Line, are examined and related to warning and alarm indications from a wheel defect detector installed on the same line. The study shows that an increased wheel wear, detectable by changes in the wheel profile parameters could be used to reduce the risk of capacity-consuming wheel defect failure events and its reactive measures.

Society demand for more sustainable transports is increasing, starting a modal shift from road to railway. The resulting increase in railway traffic intensity is leading to more activities on the track, even during the night time. For many years continuous urbanization has been resulting in a higher density of residents in areas close to railway tracks. The combination of these factors is raising the issue of noise disturbances from railway transports, which is forcing infrastructure managers to take action to combat noise from railway traffic systematically. There are different types of noise emanating from railways and one of the most annoying is curve squeal noise. This paper deals with the curve squeal phenomenon, the places where it occurs, and different methods for reducing it. The curving behaviour of a vehicle plays an important role in the generation of curve squeals, and therefore the way in which different rail profiles affect the capability to steer in a sharp curve is dealt within this paper. The paper is based on two case studies with investigated curves in urban regions that suffer from squeal noise, and in which comparisons between measurements and simulations were performed. The outcome of these studies is a workflow for combating squeal noise, results concerning the effects of a top-of-rail friction modifier on noise mitigation, and a proposed rail profiles for improving the steering capability of vehicles.

The aim of this paper is to present a method for the quality assessment of data from a condition monitoring system for rolling stock wheels to ascertain if the data have the right quality to be used for further analyses. This quality assessment will also show if there are variations between different measurement units for the same system, and if there are relations between different wheel parameter measurements, speed and time. The assessment of data is accomplished using the quality dimension freedom of error. There are two different data sources, namely an automatic wheel profile measurement system and a manual wheel profile measurement device. The manual measurements of wheel profiles are used for verifying the accuracy of the automatic wheel profile measurements, which constitute the larger data set. The proposed method for evaluating the data quality is demonstrated using the data from a specific condition monitoring system. The results show some inconsistencies indicating that this system lacks quality in the dimension of freedom of error and that there is need for internal calibration or self-adjustment of the studied system for quality reasons.

Turnouts are critical units in a railway system; they perform the switching procedure that allows trains to change between routes. Monitoring the track geometry of a turnout is necessary for maintenance planning and design optimisation. Monitoring is usually done by track recording cars, however, to isolate the ageing and dynamic behaviour of the track it is also necessary to study the unstressed track geometry of the turnouts. Such measurements can be used to develop degradation models to optimise maintenance and design, thereby increasing availability and reducing life cycle cost. This paper introduces a new method to measure the vertical position of the track geometry over time during non-operational conditions (unstressed) to show track degradation. The new method includes a smart system that uses relative measurement reference points to create a better accuracy and lower costs compared with fixed reference points. It evaluates various types of measurement equipment and uses levelling equipment to measure the unstressed vertical geometry of 13 turnouts located on Swedish railway lines, with three follow-up measurements over a year and a half. The turnouts were categorised into four groups: based on their accumulated capacity in million gross tonnes (MGT) and whether they were on a straight or curved main track. Surprisingly, the first three measurements showed the geometry of turnouts on the straight main track to have a vertical elevation tendency towards the mid-section, whereas the turnouts on the curved main track had a general vertical downwards bend tendency towards the mid-section. The results also showed that a higher capacity in MGT has a greater influence on track geometry changes over time.

Friction management in the railway industry is a well-established technology with the aim of optimizing the friction between the wheel and rail. Determining the friction coefficient (μ) at the wheel-rail interface is therefore important especially for heavy haul lines with higher axle loads. This paper presents an initial study of the top-of-rail friction condition of a line with 30 ton axle load, the Iron Ore Line in the northern part of Sweden. The friction coefficient between the rail and the metal wheel of a portable tribometer was measured at different geographical locations and in different environmental conditions. The effects of precipitation are studied and compared with the effects of top-of-rail friction modifiers.The measurements of non-lubricated line sections showed values of μ≈0.6, compared to μ≈0.3 for areas with, for example, top-of- rail lubrication. In snowy conditions a decrease in friction could also be detected.Keywords: Friction management, Friction measurement, Friction modifier, Heavy haul railway line, Swedish Iron Ore Line.

Railway transport system is massive and complex, and as such it requires effective maintenance to achieve the business goal of safe, economic and sustainable transportation of passengers and goods. The growing demand for improved service quality and capacity target by railway infrastructure managers requires appropriate maintenance analysis to facilitate continuous improvement of infrastructure performance. This paper presents the application of risk matrix as a maintenance analysis method for the identification of track zones that are bottlenecks that limit operational capacity and quality. Furthermore, an adapted analysis method is proposed to create a hierarchical improvement list for addressing the problem of train mission interruption and reduced operational capacity. A case study of a line section of the Swedish network is presented. The result classifies the zones on the line section into different risk categories based on their contribution to loss of capacity and punctuality. In addition, an improvement list for the lower-level system is presented to facilitate maintenance decisions and continuous improvement at both operational and strategic levels.

The real friction coefficients between the rails and the wheels on a 360. t and 10,800. kW IORE locomotive were measured using the locomotive[U+05F3]s in-built traction force measurement system. The locomotive consisted of two pair-connected locomotives had a CoCo+CoCo bogie configuration, and hauled a fully loaded set of 68 ore wagons (120. t/wagon). The measurements were performed both on rails in a dry condition and on rails lubricated with a water-based top-of-rail (ToR) friction modifier on the Iron Ore Line between the cities of Kiruna and Narvik in Northern Sweden and Norway, respectively. Since full-scale measurements like these are costly, the friction coefficients were also measured at the same time and place using a conventional hand-operated tribometer, with and without the ToR friction modifier. The most important results are that the real friction coefficient is definitely not constant and is surprisingly low (0.10-0.25) when the ToR friction modifier is used, and that it is also significantly dependent on the amount of ToR friction modifier. A large amount will reduce the friction coefficient. Furthermore, it is concluded that the real friction coefficients are in general lower than the friction coefficients measured with the hand-operated tribometer. A final remark is thus that the use of a water-based ToR friction modifier can give excessively low friction, which can result in unacceptably long braking distances.

Optimum allocation and efficient utilisation of track possession time are becoming important topics in railway infrastructure management due to increasing capacity demands. This development and other requirements of modern infrastructure management necessitate the improvement of planning and scheduling of large-scale maintenance activities such as tamping. It is therefore necessary to develop short-, medium- and long-term plans for performing tamping on a network or track section within a definite time horizon. To this end, two key aspects of infrastructure maintenance planning are considered in this paper, deterioration modelling and scheduling optimisation. An exponential deterioration function is applied to model the geometry quality of a series of 200 m segments of a 130 km line section, and an empirical model for recovery after tamping intervention is developed. These two models are subsequently used to generate a methodology to optimise a schedule for tamping intervention by minimising the total cost of intervention including the cost of track possession while geometry quality is ascertained to be within a desirable limit. The modelling considers two types of tamping interventions, preventive and corrective, with different intervention limits and tamping machines. The result of this paper suggests a tamping plan which will lead to optimum allocation of track possession time while maintaining the track geometry quality within specified limits.

Purpose – The purpose of this paper is to investigate the failure-driven capacity consumption of wheels on the track, to determine whether there are some relations to vehicle wheel configurations that show a larger amount of failures, and to ascertain the influence of the temperature and the travelling direction of the train on the number of events. This information can be used to develop prognostic health management (PHM) so that more track capacity can be gained without modifications, re-building or re-investments. Design/methodology/approach – This paper presents a study of 1,509 warning and alarm events concerning train wheels. The data come from the infrastructure manager’s wheel defect detectors and wheel profile measurement system. These data have been analysed and processed to find patterns and connections to different vehicles, travelling directions and temperatures. Findings – Lower temperatures increase the probability of wheels having high vertical forces. Trains with different wheel configurations show different results. With high vertical forces, the probability of wheel failures at axle 6 and 7 is high for locomotives with two bogies and three axles in each bogie (2x3). All these findings can be used to develop the maintenance, monitoring and inspection principles for wheels. Practical implications – The inspection of wheels to detect failures needs to be more frequent on days and in seasons with lower temperatures. The wheel inspection should be performed more frequently at axle 6 and 7 for locomotives with a 2x3 wheel configuration. The inspection and monitoring of wheels need to be carried out more carefully for trains travelling south, to avoid a large amount of wheels with high force levels rolling in the southern direction. Originality/value – The analysis carried out in this paper identifies important factors that correlate with the high occurrence of wheel defects. It also proposes a conceptual e-maintenance model for the combination of wheel condition monitoring data from different system. The value of this study is the provision of information to support prognostic and health management system to support proactive maintenance.

Due to the more or less fixed inherent capacity of a railway system, capacity consuming events like failures within a railway network should be kept to a minimum. This could be achieved by the use of existing and new condition monitoring systems which can detect, report and predict failure events in an early stage. Demands for higher service quality, higher capacity, network availability and track quality together with less human intervention on tracks, drive the development of railway condition monitoring systems.Failure driven capacity consumption due to worn or defected rolling stock wheels have a big impact on the capacity and the infrastructure condition. Wheel defects such as out-of-round wheels, generates high forces, and could result in large capacity consumption especially for areas with cold climate conditions. Bad wheels cause even higher track wear that reduce the life length of the track. Wheels with fatigue defects could also influence the track safety issues. This paper presents how different wheel defects can be monitored; together with a review of the most common wayside condition monitoring systems on the Swedish railway network. The study also describes how the decision making process could take advantage of the condition monitoring data in order to increase the achieved network capacity.