Track Renewal Research Articles

Track Bed Total Route Evaluation for Track Renewals & Asset Management “A Network Rail Perspective”

Track Bed Total Route Evaluation for Track Renewals & Asset Management “A Network Rail Perspective”

Integrating Machine Learning in Geotechnical Engineering: A Novel Approach for Railway Track Layer Design Based on Cone Penetration Test Data

The cone penetration test (CPT) has emerged as a cost-effective and time-efficient method for assessing soil conditions relevant to railway track infrastructure. The geotechnical data obtained from the CPT serve as crucial input for asset managers in designing optimal sublayers and form layers for track renewal works. To properly assess the condition of soil layers, various soil behavior type charts and machine learning models based on CPT data have been published to help engineers classify soils into groups with similar properties. By understanding the properties of the soils, an optimal substructure can be designed to minimize extensive maintenance and reduce the risk of derailment. However, when analyzing multiple CPTs, the diversity and non-uniformity of subsoil characteristics pose challenges in designing a new optimal trackbed. This study presents an automated approach for recommending thicknesses of sublayers and form layers in railway tracks based on CPT data, employing machine learning algorithms. The proposed approach was tested using CPT data from the Belgian railway network and showed very good agreement with results from traditional soil investigation interpretations and layer design. A Random Forest classifier, fine-tuned through Bayesian optimization with a cross-validation technique and trained on 80% of the datasets, achieved an overall accuracy of 83% on the remaining 20%. Based on these results, we can conclude that the proposed model is highly effective at accurately designing sub-ballast layers using CPT data.

Modelling degradation rates of track geometry local defects: Lisbon-Porto line case study

The proper scheduling of track maintenance and renewal operations is dependent on the accuracy of predictive maintenance outputs which, in turn, rely on the appropriate modelling of the track geometry degradation process. This paper explores the incidence and representativeness of the alerts generated due to local defects of track geometry and the modelling of their degradation rates between consecutive tamping operations. A software tool was developed and used to process track inspection data collected over 12 years of operation of the main Portuguese line (Lisbon-Porto) on a total of 727 km of single-track lines where speeds vary between 30 and 220 km/h. Linear regressions are found to be suitable to model the degradation rates of local defects of longitudinal levelling, alignment and twist in the vast majority of cases, although 20–30% of the time degradation patterns prove to be non-linear even in the short term. The local defects of alignment degrade more rapidly and trigger 80% of the unplanned maintenance needs. Modelling the evolution of local defects, and not only the standard deviation on sections 200 m long, allows us to anticipate unplanned maintenance and tackle unavailability costs.

Efficient Reuse of Railway Track Waste Materials

Some of the most important materials that need recycling are generated by the construction industry. This waste has a multitude of disposal problems. In the specific case of railways, the treatment of materials taken from track maintenance and renewal operations is even more challenging. Every year, tons of track materials are replaced on rail tracks all over the world. These kilometres of rails, sleepers, and tons of ballast can be reused for other purposes. However, sometimes the environmental cost generated by their secondary use is worse than the problems involved in their disposal. This work describes a revised methodology to improve the recycling process of these waste track materials and considers the carbon footprint generated during the process along with important advantages and benefits for the economy and the environment. The reuse of these worn track materials is important to extend their life cycle and reduce environmental and economic costs in the long term. This research aims to analyse dismantled track material and evaluate possible second uses, taking into account the carbon footprint generated. Special attention has been placed on environmentally friendly uses such as fencing protected areas or green routes, among others.

Justification of the structure and determination of the mathematical model parameters for a mechanical system with tribospectral optimization

The questions of determining the structure and parameters of the working bodies mechanical system model for the track renewal train with tribospectral optimization are considered. It is proposed that the tribospectral characteristics should be considered as an optimization parameter recognition source. The main attention is paid to the identification of the main regularities in the realized tribospectrum of the useful vibration signal. Based on the results of processing the vibration acceleration spectra, possible signs of optimization assessment are proposed.

Embodied greenhouse gas assessment of railway infrastructure: the case of Austria

This study assesses life-cycle greenhouse gas (GHG) emissions associated with the entire railway infrastructure network of Austria, a first detailed study for a country, modelled through a top-down approach. Railway track is analysed for the first time in detail for a variety of specific boundary conditions using a bottom-up approach focusing on track renewal and maintenance. The methodology of standard elements allows for quantification of expected maintenance demands over the life cycle as well as determination of service life (SL). For this, the network is clustered into the main condition-affecting parameters, and documented maintenance and renewal measures are analysed and interpreted accordingly to estimate future behaviour. This Austrian approach used for assessing life-cycle costs serves as input for evaluating environmental impacts, a novel model. Data were gathered via environmental product declarations, governmental publications and company-specific environmental reports to correspond to the standard supply chains of the Austrian Federal Railways' (ÖBB) life-cycle (manufacturing, construction, maintenance and reuse/recycling) infrastructure practices, and reflect actual transport distances, transport modes, the Austrian electricity mix and emissions. The railway infrastructure causes 235 000 tonnes of CO2eq emissions per year (0.3% of Austria's total) based on the current infrastructure network, asset distribution and renewal rates. Within railway infrastructure, the track (including rails, fasteners, sleepers and ballast) is the main contributor to GHG emissions with 55% of the total. The GHG emissions associated with concrete tunnels are 16 times larger per kilometre per year than the railway track, but supply only 22% of the total emissions. The railway infrastructure contributes an additional 141% of GHG emissions over emissions from passenger traffic, which is much higher than previously anticipated. In-depth analysis of railway track shows that concrete sleepers with under-sleeper pads come with lower environmental impacts than conventional concrete sleepers. Higher traffic loads as well as narrow curves cause a significant increase in environmental impacts. For rails in a straight section with an SL of 50 years and two grinding measures, the costs regarding GHG emissions amount to €6500 per kilometre (including the production, construction and use phases) when calculating with a cost of €20 per tonne CO2eq on the market. Currently, this equals around 5% of the economic costs, but is expected to significantly increase as costs for environmental impacts are set to increase until 2050. Mitigation potential can be found in special rail steel production, reuse of materials, use of alternative fuels and efficient maintenance strategies.

Підвищення рівня безпеки залізничних пасажирських та вантажних перевезень

In 2020, the Ukrainian Government conducted an audit of the Ukrainian economy for nearly 30 years of independence and decided on the vectors of economic development aimed at European and Euro-Atlantic integration. The audit of the Ukrainian railways showed that most of the railway assets are critically worn. The audit and the vectors became a starting point for the development of the National Economic Strategy of Ukraine up to 2030, which was approved on March 3, 2021. One of the priorities of this strategy is the development of the transport sector by a succession of steps, including railway track and vehicle renewal, the introduction of high-speed passenger transport, and increasing railway traffic safety and environment safety on the Urrainian railways. The aim of this paper is to work out recommendations on increasing the safety of passenger and freight traffic in Ukraine. The paper generalizes the experience gained over the years of Ukrainian independence in the fundamental and applied transport-oriented reseach conducted at the Department of Sttistical Dynamics and Multidimensional Mechanical Systems, Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine. This experience may be useful in the implementation of the above steps on the way to the sustainable development of the Ukrainian railway transport. In the paper, emphasis is on new investigations into the passive propection of the cars of a motor car train in emergency collisions whose scenarios are specified by Ukrainian State Standard DSTU EN 15227. Based on a mathematical model of a collision of identical motor car trains, a mathematical model was developed to simulate a collision of a motor car train with a large vehicle at a crossing with account for a specified force characteristic of interaction of the leading car equipped with a passive safety system with a deformable obstacle. The model developed was used in analyzing dynamic loads on the cars of a motor car train with a passive safety system in its collision at 110 km/h with a 15 t large vehicle at a railway crossing. With consideration for the results of previous investigations into the dynamics of emergency collisions of a motor car train with an identical train and a fright car, recommendations were worked out on the passive protection of a home-made leading car in accordance with the requirements of normative documents. The proposed mathematical models and designs of energy-absorbing devices, the research results, and the practical recommendations worked out may be used in designing new motor car train vehicles for the Ukrainian railways in accordance with the DSTU EN 15227 requirements for passive protection in emergency collisions.

ЖОЛ ЖӨНДЕЙТІН ВПО-3-3000 МАШИНАЛАРЫНЫҢ КӨТЕРГІШТЕГІСТЕУ ҚҰРЫЛҒЫСЫ КОНСТРУКЦИЯЛАРЫНЫҢ БЕРІКТІЛІК СИПАТТАМАЛАРЫН БЕЛГІЛЕУ

The This article deals with the replacement of the magnetic grippers on the VPO-3-3000 machines with roller grippers. The novelty lies in the establishment of dependences characterizing stress and strain in the elements of the lifting and straightening devices and in the rails during the operation. Reliability of the program for calculating the structural parameters of the lifting and straightening device for the VPO-3-3000 track renewal machine is shown. The developed design of the lifting and straightening device makes it possible to select the rational parameters of the technology and the operating mode of the device. It This design is recommended to for use it when developing working bodies for the straightening machines. The article presents the calculation of the lifting and straightening device structural elements' strength during its operation, in the Ansys WB software package.

Establishing the Strength Characteristics of the Lifting-Leveling Device Structures of the VPO-3-3000 Machines for the Track Straightening

This article deals with replacement of the magnetic grippers on the VPO-3-3000 machines with roller grippers. The novelty lies in establishment of dependences characterizing stress and strain in elements of the lifting and straightening devices and in rails during the operation. Reliability of the program for calculating the structural parameters of the lifting and straightening device for the VPO-3-3000 track renewal machine is shown. The developed design of the lifting and straightening device makes it possible to select the rational parameters of technology and the operating mode of the device. This design is recommended for use when developing working bodies for the straightening machines. The article presents calculation of the lifting and straightening device structural elements' strength during operation, in the Ansys WB software package.

Measurement Data-Driven Life-Cycle Management of Railway Track

Track engineers face increasing cost pressure and budget restrictions in their work today. This leads to growing difficulty in legitimizing crucial maintenance and renewal measures. As a result, infrastructure managers must ensure they invest all available financial resources as sustainably and efficiently as possible. These boundary conditions require an objective tool enabling both a component-specific condition evaluation and preventive maintenance with renewal planning. The present research introduces such a tool for railway tracks based on innovative track data analyses. This tool includes time-series analyses for predicting future quality behavior. Consequently, the technical necessity of maintenance actions can be derived for every specific track section. In addition, these technical evaluations are combined with economic and operational considerations to plan reasonable maintenance lengths for different track components in the next few years. In a further step, business evaluations by means of annuity monitoring are executed to determine whether ongoing track maintenance or complete track renewal is the most economical solution. This methodology also allows calculating the economic damage caused by neglecting the ideal point in time for reinvestment. On the basis of this economic damage, it is possible to rank projects by priority in the case of insufficient budgets and to ensure that all available resources are invested in the most reasonable manner possible. Furthermore, such analyses clearly show that when a specific degradation level of railway track is reached track renewal is more economic in relation to life-cycle costs than ongoing maintenance.

Potential for improving the environmental performance of railway sleepers with an outer shell made of recycled materials

An innovative sleeper with a pre-stressed reinforced concrete inner structure wrapped by an outer shell manufactured with end-of-life tires powder and recycled plastics has been recently designed by the Greenrail company. The external protection is aimed at increasing its lifetime and reducing the maintenance requirements of the railway lines. This study evaluates the environmental performances of this sleeper, under different operational conditions, in comparison with traditional pre-stressed reinforced concrete sleepers, using the Life Cycle Assessment methodology.The assessment includes 16 environmental, energy, and human health impact categories. It is performed considering the following functional unit: 1 railway sleeper, including the fastenings of the rail to the sleeper and the portion of the track bed underneath it, over one year of operation. The evaluated system includes the sleeper production, its installation, the railway maintenance, the sleeper removal at its end-of-life and the final recovery. Moreover, the ballast is included in the analysis considering its mining and transportation to the railway line, the partial replacement during maintenance operations, the removal during a track renewal, and the end-of-life management.For the worst operational conditions of the Greenrail sleeper, the potential impacts between the two sleeper typologies differ by <10% for most of the examined categories, meaning that no significant environmental differences are observed. In the average conditions, impact reductions for the Greenrail sleepers result bigger than 10% for 7 out of 16 categories. Finally, for the best conditions, benefits are in the range 20% - 30% for 11 impact categories.

The marginal cost of track renewals in the Swedish railway network: Using data to compare methods

We analyze the differences between corner solution and survival models in estimating the marginal cost of track renewals. Both approaches describe the renewal process in intuitively similar ways but have several methodological distinctions. Using Swedish data for the 1999–2016 period, results suggest the median marginal costs per gross ton-km from corner solution and survival models are SEK 0.0066 and SEK 0.0031, respectively. Since several European countries use information about marginal costs as a basis for track user charges, the choice of estimation method is obviously important. Our conclusion is that the corner solution model is more appropriate in this case, as this method considers the impact traffic has both on the probability of renewal and on the size of the renewal cost. The survival approach does not consider the latter as part of the estimations, which is problematic when we have systematic cost variations due to traffic and infrastructure characteristics.

Expert System – A Case of Indian Railway’s Track Maintenance and Renewal Operations

This paper develops an Expert System (ES) that augment decision-making for the ‘railway-track maintenance and renewal’ operation at Indian Railways. After consultations with experts in three selected areas (rails, sleepers and ballast) to understand the railway track operations a set of rules were formulated. Using the open-source CLIPS tool and based upon the set of rules, a user-friendly single interface system is designed for decision-making. This ES thus developed. through the interface, aids the end-user in the decision-making.

Design, procurement and coordination of the Ordsall Chord rail project, Manchester, UK

The Ordsall Chord in Manchester, UK is a new railway viaduct and associated track alteration, renewal and re-signalling scheme to provide a direct connection between the city’s Piccadilly and Victoria stations. Completed and opened to traffic in December 2017, it was designed and delivered to achieve the aspirations for a landmark structure within a constrained and complex setting. This paper highlights the benefits of the alliance procurement arrangement, which enabled genuine collaboration between the parties and early engagement of specialist sub-contractors. The benefits of installing adequate monitoring instrumentation are also discussed.

RESEARCH OF RAILWAY TRACK PARAMETERS IN THE PLAN BASED ON THE DIFFERENT METHODS OF SURVEY

Purpose. The main purpose of this paper is to analyze the existing methods for surveying curves in a plan, to study the influence of the errors in measuring plan parameters on the permitted speeds of motion, to develop re-commendations for reducing road disturbances by bringing the parameters of curves to the standards that operate in Ukraine in the directions of accelerated and high-speed train traffic. The problem of restructuring the curves was not so acute until there was a need to increase the speed of motion and technical condition monitoring of the track plan. Unreliable determination of the curves parameters leads to unjustified restrictions in the speed of motion or to large volumes of straightening operations. Methodology. The methodology used in the paper provides for a comprehensive and detailed study of different ways of railway curves survey, aimed at developing and obtaining the optimal solutions for the railway track plan. To date, there are different methods of survey the actual geometry of the railway track. To carry out research in various sections of complexity and for a long time of the railway track operation, the most convenient, first of all, considering the regularity of arrivals, there is a tape of the track-measuring car. However, this method is used to assess the state of the railway track, and not to determine the exact geometric position. Thus, when trying to determine the actual outline of the track unevenness using a track-measuring tape, a number of difficulties arise. When forming a mathematical model of the existing plan, the assumption is used: it is considered that three adjacent points on the curve are located along the circumference. The work of track renewal trains is based on this principle. As a result of track renewal operations with the aim of reducing the volume of flattening, the curve does not correspond to the initial passport data. Findings. The results of the work come out of the analysis of different approaches and methods of surveying the plan of the line, the parameters influence of the curves on establishing the permissible speed of motion. The recommendations received in the work will help to increase the efficiency of design decisions and the quality of railway track reconstruction as a whole. Originality. Scientific approaches to assessing the state of curves, studying the influence of their parameters on the permissible speed of trains, have been further developed. The system of criteria for assessing the state of curves that affect the accumulation of track disturbances in the plan is supplemented. Practical value. The results obtained will be useful for carrying out measures to improve speed, improve the smoothness of train traffic and the level of travel comfort on curved track sections, especially in the areas of accelerated and high-speed train traffic.

Optimizacija održavanja i remonta željezničkih kolosijeka primjenom genetičkih algoritama

Optimizacija održavanja i remonta željezničkih kolosijeka primjenom genetičkih algoritama

Life-cycle assessment and repair of the railway transition zones of an existing bridge using geocomposite materials

The railway infrastructure is a very important component of the world’s total transportation network. Investment in its construction and maintenance is therefore significant on a global scale. Up to now, some results of the life-cycle assessment (LCA) of open railway line, as well as railway bridges and tunnels, have been published, but detailed analyses of transition zones have not so far been performed. In railway networks, transitional zones are a critical area where the transition from open rail to solid bridge construction can cause significant settlements. The goal of these analyses was to compare two different types of track renewal methods for railway transition zones. In the first method, traditional cement stabilisation is used, whereas the second solution makes use of a geocomposite anchored by steel anchors. The paper presents some results from an environmental study for railway transition zones based on the demonstration case. The results of the performed LCA showed that, in the case of track renewal for transition zones by means of a geocomposite and anchors, the environmental impact is lower than in the case when cement stabilisation works are performed. Less extensive excavation works and thus lower quantities of used material are additional benefits.

Marginal railway track renewal costs: A survival data approach

In this paper, renewal costs for railway tracks are investigated using survival analysis. The purpose is to derive the effect from increased traffic volumes on rail renewal cycle lengths and to calculate associated marginal costs. A flow sample of censored data containing almost 1300 observations on the Swedish main railway network is used. We specify Weibull regression models, and estimate deterioration elasticities for total tonnage as well as for passenger and freight tonnages separately. Marginal costs are calculated as a change in present values of renewal costs from premature renewal following increased traffic volumes. The marginal cost for total tonnage is estimated to approximately SEK 0.002 per gross ton kilometre.

Strategic Model to Optimize Railway-Track Renewal Operations at a Network Level

AbstractThis paper presents an optimization model for scheduling railway ballast, rail, and sleeper renewal operations at a network level. The objective of the model is to minimize the expected railway track life-cycle cost (LCC) and track unavailability costs derived from user impacts caused by traffic disruption during track renewal operations. To minimize costs, the model assesses the opportunistic renewal of railway track components and takes advantage of planning from a network perspective to study the possibility of reusing track components on different lines. The practical utility of the model is illustrated with a case study involving the Portuguese railway network. The results indicate that user costs have an important influence on decision making in the track renewal process and that the network perspective of renewal planning can reduce the direct costs of these operations.

Remediation of Mud Pumping on a Ballasted Railway Track

Maintenance of ballasted railway tracks is a major cost for railway infrastructure owners. In many developed countries, much of the railway infrastructure is mature and was built for service requirements long since superseded. The increased demands on historic infrastructure can lead to the development or exacerbation of localised trackbed problems that require disproportionate levels of maintenance. Identifying these and applying cost effective remediation has the potential to reduce maintenance spend in the long term. However, it is not always clear what the most cost effective remediation will be. One type of localised maintenance issue is the development of wet beds or wet spots, which can occur where saturated clayey subgrade soils are overloaded and result in the development of mud pumping as trains pass. This leads to the migration of fines into the ballast bed and a deterioration in local track performance. Over time the track overlying the wet bed settles disproportionately more, sleepers become progressively more voided, and train ride quality deteriorates. Maintenance of the wet bed may involve locally digging out and replacing the ballast; however, unless the underlying cause is addressed the problem is likely to recur, requiring repeated localised maintenance interventions. This is costly, reactive and ultimately an ineffective approach to managing the problem. This paper presents a study of a wet bed in the UK, both prior to and after a full track renewal. Transient track deflections during train passage were monitored using sleeper mounted geophones and high speed filming techniques. Loaded track geometry data were obtained from a track recording vehicle. It is shown that local maintenance interventions were generally ineffective, but that a renewal of the top 200mm of the trackbed including placement of a geotextile filter and geogrid appears to have been successful in remediating the problem, at least in the short term.