Rail Maintenance Research Articles

Pin-on-disc study of the effects of railway friction modifiers on airborne wear particles from wheel–rail contacts

Knowledge of wheel–rail interaction is crucial to wheel and rail maintenance. In this interaction, some of the worn-off material is transformed into airborne particles. Although such wear is well understood, few studies treat the particles generated. We investigated friction modifiers' effects on airborne particle characteristics generated in wheel–rail contacts in laboratory conditions. Pin-on-disc machine testing with a round-head pin loaded by a dead weight load 40N simulated maximum contact pressure over 550MPa. Airborne particle characteristics were investigated in dry contacts and in ones lubricated with biodegradable rail grease and water- and oil-based friction modifiers. The number of particles declined with the grease; the number of ultrafine particles increased with the water-based friction modifier, mainly due to water vaporization.

Negative safety events as correlates of work-safety tension

We investigate the extent to which three types of self-reported negative safety events (i.e., being injured at work, working in an unsafe way, witnessing others working in an unsafe way) correlate with work-safety tension. Work-safety tension is bi-dimensional, defined here as the perceived conflict between production and following safety rules (“barriers to safety compliance”) and production and proactive ways of working more safely (“barriers to safety participation”). Directly experiencing or witnessing negative safety events may send signals to employees about the extent to which their organization prioritizes production over safety. We tested a model of negative safety events as predictors of both barriers to safety compliance and barriers to safety participation using survey data from 316 front-line supervisors (97% male, mean age=44years) working for a UK rail maintenance company. The number of injuries directly experienced had a positive relationship with perceived barriers to safety compliance, whereas the number of times respondents witnessed others work in an unsafe way had a positive relationship with perceived barriers to safety participation.

Use of scenarios and function analyses to understand the impact of situation awareness on safe and effective work on rail tracks

This paper illustrates the value of the notion of situation awareness in the context of rail maintenance and trackwork. Illustrative scenarios, based on reported incidents, are analysed to demonstrate the nature of situation awareness in trackwork. A functional analysis is then presented to understand how situation awareness is constructed and maintained in trackwork and the types of events or disrupting factors that might lead to human factors risks to safety and productivity. These analyses highlight the importance of a shared understanding of both location and time for the protection required in trackwork, resilience in the face of short term re-planning, expertise and local knowledge, and the importance of effective strategies for distributing awareness across people and artefacts.

Detection of White Layer on Rail by Using SQUID

White layers, which often cause a break of a rail, are generated on its top surface when train wheels spin on it. Therefore its early detection of damaged conditions of the rail that may lead to a break is a critical activity in the rail maintenance. In this study, we have developed an effective method to detect the white layer on the top surface of the rail by using a Superconducting Quantum Interference Device (SQUID).

레일표면손상이 접촉피로수명에 미치는 영향

Rails are subjected to damage from rolling contact fatigue, which leads to defects such as cracks. Rolling contact fatigue damages on the surface of rail such as head check, squats are one of growing problems. Another form of rail surface damage, known as “Ballast imprint” has become apparent. This form of damage is associated with ballast particles becoming trapped between the wheel and the surface of rail. These defects are still one of the key reasons for rail maintenance and replacement. In this study, we have investigated whether the ballast imprint is an initiator of head check type cracks and effect of defect size using Finite element analysis. The FE analysis were used to investigate stresses and strains in subsurface of defects according to variation of defect size. Based on loading cycles obtained from FE analysis, fatigue analysis for each point was carried out.

Understanding human factors in rail engineering: re-analysis of detailed, qualitative data on functions and risks

The paper reports on the review and re-analysis of information that has been collected in earlier field studies on the functions and associated risks in rail engineering and maintenance. Two methods of Cognitive Work Analysis have been adapted and used to identify and represent important components of the rail engineering system and the situations in which activities occur. Additional classification exercises have been used to determine issues of strategic importance to the organisation, related to the functions and human factors risks in performing these functions. The effectiveness of the methods in this industrial context has been evaluated. Conclusions are drawn on how this type of approach can be used to produce relevant findings on the following: What the organisation knows about roles, functions and descriptions of tasks that are relevant for engineering and maintenance work; (2) the HF risks for today's (and unless things change), tomorrow's railway; (3) how this knowledge can help in determining organisational priorities for future work.

Analysis and modeling of rail maintenance costs

Article history: Received July 10, 2011 Received in Revised form September, 12, 2011 Accepted 25 September 2011 Available online 30 September 2011 Railroad maintenance engineering plays an important role on availability of roads and reducing the cost of railroad incidents. Rail is of the most important parts of railroad industry, which needs regular maintenance since it covers a significant part of total maintenance cost. Any attempt on optimizing total cost of maintenance could substantially reduce the cost of railroad system and it can reduce total cost of the industry. The paper presents a new method to estimate the cost of rail failure using different cost components such as cost of inspection and cost of risk associated with possible accidents. The proposed model of this paper is used for a realworld case study of railroad transportation of Tehran region and the results have been analyzed. © 2012 Growing Science Ltd. All rights reserved.

Investigating presentation of rail-specific spatial information on handheld computer screens

Spatial information is one of the most commonly used items of information for rail maintenance workers and providing this information to track workers while mobile offers potential advantages in terms of efficiency and communication accuracy. However, displaying track diagrams and other rail-specific spatial information on the small screen of a handheld computer presents several human computer interaction challenges that need to be considered. Three experiments were conducted to investigate different aspects of presenting spatial information on handheld computers. These experiments were conducted with current job holders at their place of work. The first experiment aimed at investigating the differences between presenting rail-specific information on handheld computers compared with paper-based documents. Using a combination of qualitative and quantitative methods, the findings of this experiment demonstrate the potential for handheld computers to provide a more efficient and effective means of displaying rail spatial information. The second experiment aimed to discover the optimum amount of information that can be presented on the screen of a handheld computer device. The results of this experiment demonstrate that although different combinations of length of track and amount of information affect user's performance, the structure of spatial information displayed on the screen is also very important. The third experiment identified that although the type of information presented to the track workers did not have an effect on their performance, postexperiment interviews revealed the importance of the type of information for track workers depending on the type of task they perform. These findings have implications for the design of small screen representations of spatial information in future mobile devices.

Development of the Wheel—Rail Interface Management Model and Its Applications in Heavy Haul Operations

This article describes the wheel—rail interface management (WRIM) model being developed by Transportation Technology Center Inc. to evaluate wheel—rail interface conditions, plan wheel—rail maintenance, and develop strategies to improve railway system performance. The WRIM software integrates wheel—rail profile measurement data, vehicle performance data, track geometry data, and rail steel properties to predict rail wear and rolling contact fatigue (RCF) based on the shakedown theory, an energy-based RCF damage function, and existing wear rate computation algorithms.

Influence of Type of Grinding Stone on Rail Grinding Efficiency

Rail grinding using a grinding stone has long been a regular part of rail maintenance. This paper discusses the development and evaluation of a new type of high-performance grinding stone. Prototype stones were tested on a grinding test bench with rotation speed and pressing load as the bench test conditions. Grinding capacity of the new grinding stone was compared with that of the current grinding stone. Metallographic analyses of the rail specimens after grinding were also conducted. The findings showed that the proposed stone improved grinding capacity. The new stone also improved grinding performance due to its more moderate impact on rails from a metallographic point of view. These findings indicate that the prototype grinding stone should be field tested as a substitute for the current grinding stone.

AN APPROACH FOR RISK ASSESSMENT OF RAIL DEFECTS

Rail defects appear in a greater variety and frequency due to higher axle loads and increasing traffic density in passenger and freight trains. Many of these rail defects, if left undetected, can develop into rail breaks, which may lead to train derailments. Reduction in the number of such catastrophic events requires huge investments on inspection and maintenance activities. Therefore proper maintenance planning and risk assessment is required to reduce the rail maintenance cost without compromising safety. In this paper, an approach has been developed for risk assessment of rail defects to support the decision-making process during scheduling of rail inspection and grinding frequency, based on the type of defect and its risk of occurring and developing into a rail break. The approach will help in increasing the safety of passengers and rolling stock as well as reducing the overall rail maintenance cost, as it helps in making effective decisions related to inspection frequency (i.e. resource allocation according to the need). The approach is presented with the aid of a case study from the Swedish National Rail Administration (Banverket). Both, quantitative and qualitative analysis technique has been used in this paper to assess the risk of occurrence of a rail defect and its development into a rail break.

Formulation and Solution Approaches to the Rail Maintenance Production Gang Scheduling Problem

The rail industry spends billions of dollars each year on maintenance and renewal of its track infrastructure. The scheduling of these maintenance projects is extremely complex, with numerous hard and soft cost trade-offs and job scheduling constraints. Scheduling requires consideration of efficient maintenance production gang routing around the rail network while paying close attention to any train delay such maintenance projects might cause. Despite this importance and complexity, the subject has been largely ignored in the literature. We evaluate two formulations (time-space network mixed integer program and job scheduling) and three modeling formulation and solution methodologies (integer programming, constraint programming, and genetic algorithms) for scheduling rail gangs to annual renewal projects and discuss their relative merits in terms of parsimony of model formulation, solution time, and solution quality. The purpose of this paper is to identify the most fruitful avenues for further research on this novel application.

Research of rail traction shafts and axles fractures towards impact of service conditions and fatigue damage accumulation

Traction shafts and axles of railway vehicles are designed to be safe and reliable in normal service conditions. Accidental and unpredictable conditions including bad exploitation (rail tracks, maintenance and extreme long service life) make the probability of shaft and axle fracture realistic. This article contains the experience and analysis of the traction shafts and axles fractures and fracture processes. Research also shows service conditions with results presented in the form of service stress spectrums. Besides normal service conditions, the results also include unpredictable phenomenon such as natural torsion vibrations of the shaft and wheels caused by stick–slip processes at the moment of the set in motion of a full-loaded train or at the moment of braking. These vibrations create an extremely high level of torque which is the main cause of cracks initialization. The next part of the article contains the results of the traction shafts and axles endurance research. The results of testing are transformed using the results of calculation by the FE method and by statistical estimation of the failure probability distribution. The main part refers to the interaction (impact) of service stress probability and failure (endurance) probability, which leads to the traction shaft (axle) reliability definition. Using the established model, locomotive traction shaft reliability is calculated and analyzed. The final part of the article contains suggestions for the traction shafts (axles) failure prevention.

NLP helps Metronet Rail maintenance employees to stay on track

PurposeDescribes how neuro‐linguistic programming (NLP) techniques helped employees of a Tube maintenance company during a period of major organizational upheaval.Design/methodology/approachExplains the background to NLP training among the learning and development team at Metronet Rail, and the use the team members made of the techniques.FindingsDetails, in particular, how good communication, listening and empathy skills proved invaluable as the significant organizational changes unfolded.Practical implicationsReveals that NLP techniques also helped the learning and development team to develop individualized options to assist other people caught up in the change.Social implicationsHighlights how NLP techniques can help people to develop as individuals, as well as employees, to the benefit of society as a whole, as well as individual employers.Originality/valueReveals how NLP training can help to get the best out of people during organizational change.

Review of Services Science and possible application in rail maintenance

This is the final article in the Services Science and Innovation series and the intention is to do two main tasks. In Part 1 we highlight some of the key messages that are captured in the expanding discussion of the management of services which constitute the majority of most developed countries’ GDPs. In Part 2 we then test and apply some of those lessons to a practical and challenging situation in the rail maintenance sector. This draws on a collaborative two year research project and the continuing involvement of one of the authors as a participant observer in the sector. It is one of the main thrusts of this paper that the debate is often too polarised, offering rather artificially extreme views from a pure product or pure services standpoint.

Estimation of Crack Growth Life in Rail with a Squat Defect

Rolling contact fatigue initiated defects such as surface corrugation, head check, squat, are one of growing problems in high speed railway line. A squat is generally developed below the rail surface and grows parallel to surface until it turns down into rail. Estimation of critical crack size and crack growth rate is an essential to prevent rail from failure and develop cost effective railway maintenance strategy. In this study, we predict crack growth rate of a rail with a squat defect. For this purpose, a rail model with a squat defect is developed. Timoshenko’s beam theory is applied to calculate the global bending stress at the crack tip and Hertzian contact model is applied to calculate the local contact stresses at the surface of rail by simulating rolling over a railway wheel on a rail. Stress intensity factors are calculated from the total stress at the crack tip. Fatigue crack growth curve of 60kg rail steel is applied to calculated crack growth rate. Software to predict crack growth life through whole life cycle is developed. We expect that we can make a more cost effective rail maintenance strategy by considering the crack growth analysis for a defective rail.

Relationships between psychological safety climate facets and safety behavior in the rail industry: A dominance analysis

The goals of this study were twofold: (1) to confirm a relationship between employee perceptions of psychological safety climate and safety behavior for a sample of workers in the rail industry and (2) to explore the relative strengths of relationships between specific facets of safety climate and safety behavior. Non-management rail maintenance workers employed by a large North American railroad completed a survey ( n = 421) regarding workplace safety perceptions and behaviors. Three facets of safety climate (management safety, coworker safety, and work-safety tension) were assessed as relating to individual workers’ reported safety behavior. All three facets were significantly associated with safety behavior. Dominance analysis was used to assess the relative importance of each facet as related to the outcome, and work-safety tension evidenced the strongest relationship with safety behavior.

Application of fracture mechanics methods to rail design and maintenance

Railway organizations are facing continuous increase in train frequency, running speed and axle load with ever limited financial resources. This is why methods broadening knowledge of external loads and internal rail stresses are of higher importance to address rail design or maintenance process. The following paper explains how the development and application of such methods has been conducted by a european partnership (called NOVUM) between railway organizations (SNCF, DB AG, RATP) and rail producer (CORUS) sharing their specific own competences, experience and material resources. Research institutes and universities (BAM, GKSS, INRETS, INSA, LMS) have been in charge of building sound numerical simulations or experimental tests and tools. Theoretical aspects of the method are described in independent paper “A global approach for modelling fatigue and fracture of rails” [1]. A first task group of the program is dedicated to the determination of external forces coming from wheel/rail and from rail/support interactions. The second and third task groups are about material properties and internal stresses inside rail section. Laboratory and track validations are undertaken in the fourth task group. Two characteristic cases are then chosen to check the developed models.

Holistic procedure for rail maintenance in Sweden

The paper discusses a procedure for systematic and holistic (considering most of the factors influencing the rail degradation process) analysis and prediction of rail failures so that rail maintenance can be performed effectively. The current rail maintenance and reporting procedure followed by Banverket (Swedish National Rail Administration) for the Swedish Iron Ore Line is also described. The necessary data required to perform analysis and prediction of failures are discussed along with the improvement areas in Banverket's database management system. This paper will help the infrastructure managers to better understand the existing rail maintenance procedure, and the improvements which can be incorporated in the existing procedure to make it more effective.

Damage tolerance investigations on rails

The paper summarises damage tolerance investigations on railway rails which the authors have carried out in the context of the German–French joint project NOVUM (novel methods for quantitative prediction of rail performance at increased service loads) [Girardi L, Heyder R, Dider L, Boulanger D. IDR2-NOVUM promises lower rail maintenance costs. Railway Gazette Int 2005;(July):439–41 [1]]. The investigations include the determination of the crack driving force as a function of the various loading components a rail is subjected to and the simulation of residual lifetime. Features such as the local load input at the rail–wheel interface, dynamic effects and statistical aspects of crack resistance are explicitly taken into account.