The measurement and improvement of track quality are key issues in determining the time at which railway maintenance must be performed and its cost. Efficient track maintenance ensures optimum allocation of limited maintenance resources which has an enormous effect on maintenance efficiency. Applying an appropriate tamping strategy helps reduce maintenance costs, making operations more cost-effective and leading to increased safety and passenger comfort levels. This paper discusses optimisation of the track geometry inspection interval with a view to minimising the total ballast maintenance costs per unit traffic load. The proposed model considers inspection time, the maintenance-planning horizon time after inspection and takes into account the costs associated with inspection, tamping and risk of accidents due to poor track quality. It draws on track geometry data from the iron ore line (Malmbanan) in northern Sweden, used by both passenger and freight trains, to find the probability distribution of geometry faults.

In the past, railway maintenance actions were usually planned based on the knowledge and experience of the infrastructure owner. The main goal was to provide a high level of safety, and there was little concern about economic and operational optimisation issues. Today, however, a deregulated competitive environment and budget limitations are forcing railway infrastructures to move from safety limits to cost-effective maintenance limits to optimise operation and maintenance procedures. By so doing, one widens the discussion to include both operational safety and cost-effectiveness for the whole railway transport system. In this study, a cost model is proposed to specify the cost-effective maintenance limits for track geometry maintenance. The proposed model considers the degradation rates of different track sections and takes into account the costs associated with inspection, tamping, delay time penalties, and risk of accidents due to poor track quality. It draws on track geometry data from the Iron Ore Line (Malmbanan) in northern Sweden, used by both passenger and freight trains, to estimate the geometrical degradation rate of each section. The methodology is based on reliability and cost analysis and facilitates the maintenance decision-making process to identify cost-effective maintenance thresholds.

Switches and crossings (S&Cs) are one of the most critical components of railway track systems in terms of safety, operation and maintenance. Each year, a considerable part of the maintenance budget is spent on inspection, maintenance and renewal of S&Cs. However, applying a cost-effective maintenance strategy helps to achieve the best performance at the lowest possible cost. In Sweden, the geometry of S&Cs is inspected at pre-defined time intervals by the STRIX track measurement car. In this paper, time series for the measured longitudinal level of S&Cs on the Iron Ore Line (Malmbanan) in northern Sweden have been used. Two parameters have been defined in this study, namely the absolute residual area (ARa) and the maximum settlement (Smax), to analyse the geometrical degradation of switches and crossings due to dynamic forces generated from train traffic. The paper also evaluates the growth rate of the longitudinal level degradation as a function of million gross tonnes (MGT). The results facilitate correct decision making in the maintenance process through understanding the degradation rate and defining the optimal maintenance thresholds for the planning process. In the long run this will lead to a cost-effective maintenance strategy with optimized inspection and maintenance intervals.

Turnouts are critical components of track systems in terms of safety, operation and maintenance. Each year, a considerable part of the maintenance budget is spent on their inspection, maintenance and renewal. Applying a cost-effective maintenance strategy helps to achieve the best performance at the lowest possible cost. In Sweden, the geometry of turnouts is inspected at predefined time intervals using the STRIX / IMV 100 track measurement car. This study uses time series for the measured longitudinal level of turnouts on the Iron Ore Line (Malmbanan) in northern Sweden. Two different approaches are applied to analyse the geometrical degradation of turnouts due to dynamic forces generated by train traffic. In the first approach, the recorded measurements are adjusted at the crossing point and then the relative geometrical degradation of turnouts is evaluated by using two defined parameters, the absolute residual area and the maximum settlement, In the second approach, various geometry parameters are defined to estimate the degradation in each measurement separately. The growth rate of the longitudinal level degradation as a function of million gross tonnes / time is evaluated. The proposed methods are based on characterisation of the individual track measurements. The results facilitate correct decision-making in the maintenance process through understanding the degradation rate and defining the optimal maintenance thresholds for the planning process. In the long run, this can lead to a cost-effective maintenance strategy with optimised inspection and maintenance intervals.

The measurement and improvement of track quality are key issues in determining both the restoration time and cost of railway maintenance. Applying the optimal tamping strategy helps reduce maintenance costs, making operations more cost effective and leading to increased safety and passenger comfort. In this paper, track geometry data from the iron ore line (Malmbanan) in northern Sweden, which handles both passenger and freight trains, are used to evaluate track geometry maintenance in cold climate. The paper describes Trafikverket’s (Swedish Transport Administration) tamping strategy and evaluates its effectiveness in measuring, reporting, and improving track quality. Finally, it evaluates the performance of the maintenance contractor and discusses the importance of the functional requirements stated in the outsourcing contracts.

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.

Infrastructure owners monitor changes in the track geometry to safeguard operation and to plan maintenance activities. Usually, track geometry is monitored using specialized measurement vehicles assessing the track several times a year to establish information on the development of a specific locations along the track. In this paper, a prediction tool is proposed and described that combines information from the measurement vehicles with measurements of onboard monitoring systems on regular trains to estimate and predict the properties longitudinal level and twist. Further, static asset configuration and information on the infrastructure is used in the decision making to provide actionable insights. The tool provides an improved resolution in time for track geometry properties and predictions on how these properties develop in the future including information on the uncertainties.

It will be discussed how data from different sources with irregular sampling need to be preprocessed to be combined and harmonized. Moreover, in what way different principles from data science, machine learning and estimation theory can be combined with domain knowledge to enable a better analytics and decision making. To support engineers, it is shown how a decision support tool for maintenance can be tailored and used. Finally, the tool and approach are showcased and benchmarked on track systems in Europe, where both onboard monitoring data and data from measurement trains is available. The results indicate that such a tool provide improved actionable insights to practitioners.

Rail degradation is a significant problem for rail industries. Wear and fatigue comprises major component of rail degradation. It depends on operational conditions such as train speed, axle load, rail-wheel material type, size and profile, track construction, characteristics of bogie type, Million Gross Tonnes (MGT), curvature, traffic type, weather and environmental conditions. Development of prediction model related to those defects leading to rail breaks and/or rail replacements is vital for economic and safe operation of rail services. Estimation of parameter for failure models is necessary for accurate prediction of expected number of rail defects over a period of time based on Million Gross Tonnes (MGT) traffic, operating conditions and maintenance strategies. This paper focuses on collection and analysis of field data for various defects developed in rail track over a period of time for estimation of parameter for models predicting degradation of rails.

Lubrication at wheel flange and rails on sharp curves is considered as an effective solution for reducing wear loss of material from effective cross-section of rail and wheels. Rail administrations around the world have been increasing axle loads and traffic densities in rail networks. This has led to traffic initiated wear, fatigue initiated surface cracks and rail breaks. Limited research has been carried out on the overall impact of combining lubrication strategies and rail grinding. This paper presents a model for lubrication strategy and rail-grinding interval to reduce wear and rolling contact fatigue (RCF). Data from rail industry is collected and used for numerical illustration.

Rail players around the world have been increasing axle loads to improve the productivity of freight and heavy haul operations. This has increased the risk of surface cracks at curves because of rolling contact fatigue. Rail grinding has been considered an effective process for controlling these cracks and reducing risks of rail breaks. The complexity of deciding the optimal rail grinding intervals for improving the reliability and safety of rails is because of insufficient understanding of the various factors involved in the crack initiation and propagation process. This paper focuses on identifying the factors influencing rail degradation, developing models for rail failures and analyzing the costs of various grinding intervals for economic decision making. Various costs involved in rail maintenance, such as rail grinding, downtime, inspection, rail failures and derailment, and replacement of worn-out rails, are incorporated into the total cost model developed in this paper. Field data from the rail industry have been used for illustration.

Rail and wheel wear is a complex problem. Lubrication plays an important role in reducing wear and enhancing asset life. Curves and switches are the areas of major challenges. Tight curves when running dry shows wear rates higher to rapid wear, increased maintenance costs and non-availability of track due to maintenance or replacement. The economic analysis based on cut-off radius, lubricants and applicators takes a very long time using field data. Rail operators often face difficulties when selecting lubricants. Lubricant manufactures use different test standards when specifying lubricant properties. Four-ball test fails to give a meaningful indication of lubricant performance. The result is often a complex decision problem in ranking different lubricants under a particular axel load. An appropriate selection of lubricant for a particular rail application can give financial returns and extension of asset life. An experimental set up has been proposed in this paper. The experimental results are expected to be used for development of models on effective lubrication. This paper proposes experimental setups and methodology for analysis of lubrication effectiveness in heavy haul lines. Theories along with existing research to date relating to ranking of lubricants for rail applications and a criterion for the ranking is discussed. An analysis is carried out to compare lubricants used in Australian Heavy Haul lines based on manufacturer supplied specifications and experimental results.

Grinding is regularly conducted on railway tracks to prevent crack propagation and surface deterioration. However, grinding can introduce roughness on rail surfaces, potentially leading to stress and strain concentration that increase the likelihood of crack initiation. This paper proposes the utilization of surface roughness obtained by replicating the ground rail surface to assess its impact on train wheel-rail interactions. A novel approach which integrates the replicated roughness into an elastoplastic contact model, allows for a detailed assessment of its effects on contact pressure, and residual strain and stress distributions. The findings highlight the importance of considering surface roughness in predictive maintenance planning for railway infrastructure, as it can significantly influence the structural integrity and long-term performance of the track system.

Results from the European 5th Framework project “InfraStar” are presented. The InfraStar project is developing a two-material rail to increase the productivity and reliability of rail infrastructure. The two-material rail aims to be rolling contact fatigue (RCF) resistant and to reduce squeal noise.The InfraStar consortium has built a high level of wheel–rail expertise and understanding regarding RCF initiation and development, level and position of wheel–rail contact forces, and new interface materials and has gained experience in both laboratory and field test operating conditions. Within the project a validated theoretical train–track interaction model and a fatigue design model for two-material rails have been developed.This paper focuses on the field test results of the two-material rail, and how the predictions and expectations from the selection process match with the results observed in track. Results are very promising. The two-material rail prototypes, now over 1 year in track, show no RCF damage where the non-treated rail shows clear RCF damage. The development of the application process and other objectives of the InfraStar project are discussed.

Globally, railway is experiencing a major technology transformation (or paradigm shift), triggered by the enhanced utilisation of digital technology. This technological transformation affects not only the technical systems, i.e. railway infrastructure and rolling stock, but also regulations, organisations, processes,and individuals. Hence, hardware, software, but also liveware (i.e. humans) are affected. Today, the digitalisation of railway is characterised by digital services. There are also a range of challenges, e.g. data acquisition,transformation, modelling, processing, visualisation, safety, security, quality, and information assurance. To deal with these challenges, the railway industry needs to define strategies, which enable a smooth transformation of the existing configuration to a digitalised system. Digital railway requires a holistic change management approach based on system-of-systems thinking and a set of appropriate technologies and methodologies. The railway digitalisation strategy should be based on systematic risk management that address aspects of, e.g., information security, traffic safety and project risk. In addition, managing changes for a digitalised railway effectively and efficiently also requires a framework for aspects such as needs finding, requirement identification, and impact of changes for individual, teams and organisation. In this work a major case studywithin the ePilot, has been performed in context of the operation and maintenance processes of the Swedish railway. Therefore, this paper aims to propose a framework for implementing innovations and driving change in a digitalised railway.

The Swedish ore line, began in 1898 and was completed and operational by 1902. The line was later electrified and remains so to this day. A study on wheel-rail interaction, to optimize wheel and rail profiles on the Malmbanan and Ofoten lines states that there is a need to develop and apply limit values for the allowable length of single and multiple cracks on wheels. Herein, all stakeholders in the railway organization have to be involved. Provisioning of an integrated decision support system for track and vehicle contributes to increased efficiency and improved effectiveness of the maintenance process, which in turn enables achievement of business excellence. However, an integrated decision support process for maintenance is highly dependent on appropriate information logistics which enables information provisioning to various maintenance stakeholders. One emerging approach for development of eMaintenance solutions is utilization of cloud-based technologies. Cloud-based eMaintenance solutions promises smooth information logistics for maintenance decision support. Hence, the purpose of this paper is to propose an approach for condition-based maintenance decision-making relating to railway vehicle wheels, based on a cloud-based eMaintenance solution. The paper also demonstrates how the proposed approach can be implemented for estimation of Remaining Useful Life (RUL) of railway vehicle wheels.

The loss of lubricant from grease-lubricated bearing surfaces is determined by a number of different mechanisms such as side-flow out of the contacts, evaporation, drop formation, oxidation etc. Some of the drops formed behind a rolling element in a bearing will be onrolled by the next rolling element but some will be lost from the bearing. This loss of lubricant is dependent to a high degree on the speed of the air flow through the bearing and is one of the reasons for early failure of grease lubrication in bearings operating in strong, axial air streams. To evaluate the most important parameters in drop formation, the droplets being thrown out from the outlet of an elastohydrodynamic contact were analyzed using picture processing and statistical methods. An empirical model has been built to describe mathematically the principal factors involved in the volume flow thrown out into the air at the outlet side of the Hertzian contact area. For example, drops in a ball bearing will contribute to the inlet feed of oil for the next ball if it is not lost by sideways flow out from the bearing.

Many machine elements are lubricated with oil or grease. The flow of lubricant depends on different parameters such as surface roughness, surface energy, temperature, etc. A known problem with rolling bearings is that lubricants have to be refilled more frequently if a gas stream passes through the bearing. It is therefore important to know the behaviour of the lubricant in order to predict, e.g. bearing fatigue life due to a gas stream. By studying the droplets thrown out into the air after passing an elastohydrodynamic contact, the most important parameters for oil drop formation have been determined. The analysis is based on picture processing and statistical methods. The experiments show that an increase in temperature, viscosity or surface velocity will increase the total drop volume. Decreased contact pressure and pure rolling also increase the total drop volume. The volume flow, passing the Hertzian contact area, varied between 18 and 30% of the air born oil-drop flow and it is reasonable to assume that increased flow of air-borne droplets will decrease the film thickness due to insufficient replenishment.

The properties of a number of common lubricants have been measured, namely the viscosity, elastohydrodynamic lubrication (EHL) friction coefficient, density, thermal conductivity and heat capacity per unit volume. These properties have been measured within relatively broad pressure and temperature ranges. The lubricants tested were naphthenic and paraffinic mineral oils, blends of these, polyalphaolefins and a polyglycol. Physical--empirical expressions have been developed upon the basis of the measurement results and a number of lubricant constants, or lubricant parameters, have been determined for each lubricant. These expressions can be used in engineering computational tools for lubrication analysis. The use of such analyses is expected to increase into the new millennium and it is thus important to provide reliable and relevant input data

Lubricants are subjected to high pressures in many mechanical devices - notably gears, cams, piston rings and rolling element bearings. The contact pressure between the ball and the race in a ball bearing can be as high as 5 GPa. At such high pressures, it is necessary to be able to measure the rheological behaviour of the lubricant in order to obtain input data for computer simulations of rolling and sliding contacts. Lubricant manufacturers are often unable to provide information about the rheology of the lubricant at high pressures, temperatures, shear stresses and shear rates. In paper A, a new Couette rheometer was developed to measure the rheological properties of fluids at pressures up to 500 MPa. The shearrate range covers 0.5 to 20000 1/s and the instrument can operate up to 1O0°C at maximum pressure. The results from the apparatus show excellent agreement with measurements made with a failing ball viscometer on a Newtonian fluid. Criteria for non-laminar flow and viscous heating have been developed for the apparatus to verify that these effects do not significantly influence the measurements. In grease lubricated machine elements the supply of grease to the contact region is very important for long life and maintenance-free operation. For example, in a bearing application the grease is often applied within the housing but outside the bearing. For good lubrication the grease has to move from the storage space into the bearing in order to separate the moving surfaces. One important part of this grease movement is the transport from near the contact region into the rolling track. This transportation mechanism may depend on different phenomena such as: capillary forces, vibrations, drop formation, oil bleeding etc. The papers B-G in this thesis describe investigations of these various phenomena. Papers B-D deal with the drop formation of oils and greases in the outlet of an elastohydrodynamically lubricated contact and how different surface energies can affect the distribution of lubricant between the surfaces. Paper E describes the elongation of grease filaments formed when two surfaces are separating from each other, as a function of time. Measurements of the lift off (adhesion) force acting between the two solid surfaces as a function of time were also made. In paper F a ball and disc apparatus was used to study the replenishment of grease due to side slip. The inlet distance and the 'butterfly' shaped meniscus that surrounds the contact point was studied as a function of the side slip motion of the ball. The filament formation equations from paper E were extended to include the geometry of the butterfly and the inlet distance. Finally, in paper G, four deep groove ball bearings were tested in a SKF R2F test rig to evaluate how lift-off-speed and breakthrough-speed are affected by ball spin. The results are compared to film thickness calculations. The lubricants used were greases, oil bled from the greases and the base oil used for manufacturing the greases.

Malmbanan, the Swedish Iron Ore Line, runs through rough terrain including high mountains, peat, terraces situated on fjords, and numerous short bridges and culverts. The area is sub-arctic and mountainous, with a sharp gradient between the part with a maritime climate and that with a continental climate. Global warming and new climate conditions are increasing the risk of slab and snow avalanches. A cost-benefit-risk analysis, dealing with slab and snow avalanches, high spring temperatures with fast snow melting, high water levels and heavy rainfalls, was performed in 2001. A number of at-risk sections along the track were identified and some of the risks were later addressed with changes in the infrastructure and changes in train operation during bad weather conditions. During the past 10 years, the various actions taken have been continuously improved. An evaluation based on operational data shows a lower risk of trains running into hazard areas and better control of slab and snow avalanches. Other improvements are better control and monitoring of rock falls and a lowered risk for trains operating during bad weather conditions. The technical systems in use consist of instrumented arrays of poles placed along the track to indicate avalanches. Bridges have been built to permit avalanches to pass under the railway and artificial tunnels have been designed and constructed to allow avalanches to pass over the railway. Rock fall nets have been put into service and professional avalanche inspection teams have been used for risk evaluation during high-risk weather conditions

This chapter comprises a short introduction to and overview of the challenges that face engineers and researchers working in the field of heavy haul railway operations in a cold climate. If these problems are to be overcome, experts from different engineering disciplines need to work together in order to find solutions for the next generation of heavy haul operation, which will see heavier, longer and faster trains with new train control systems and operating philosophies. Malmbanan runs from the port in Narvik, across the Swedish/Norwegian border via the mines in Kiruna and Malmberget, to the port in Luleå on the coast of the Gulf of Bothnia. The 100 year old ore line runs through rough terrain including high mountains, peat, terraces situated on the fjords in Norway and numerous short bridges and culverts, and part runs above the Arctic Circle. Over the course of its life, the line and its ore traffic have been continuously upgraded. Today 750 m long trains with 30 tonne axle loads are in operation. If cost-efficient operation is to be maintained, engineers must continue to seek new and effective maintenance and operating systems for both infrastructure and rolling stock.

Soap lumps entering a grease-lubricated elastohydrodynamic lubrication (EHL) contact were traced as they passed through the contact by using optical interferometry in a standard Ball & Disc apparatus and a high-speed video camera with light enhancer. One specific soap lump could be traced when it was passing through the contact and sharp images of the passing lump could be captured. This paper presents a combined experimental and numerical approach to determine what is happening when such lumps pass through the contact. From the fringe pattern, obtained by optical interferometry, a film thickness map is created by using image processing. This is done for every time step (1 ms) as the lump is passing through the contact. These maps serve as input to a numerical computation of the pressure by assuming elastic deformation theory. Consequently, no assumptions about the rheological behaviour of the grease have to be made. Two greases were studied, based on the same synthetic poly-α-olefin but thickened with Li-12-OH and Li-complex respectively. It is seen that the soap thickened lumps can cause deep elastic indentations accompanied by large pressure fluctuations. The pressure level will in some cases be more than doubled due to lumps entering the contact region. The effects on noise level and operational life are also discussed.

An upgrading programme started in 1998 and due to be completed by 2010 is allowing the introduction of heavier axleloads on Sweden's heavy haul iron ore line, permitting gross train weights to be increased to more than 8 000 tonnes. But the transition requires careful management if degradation of the infrastructure is to be kept under control