Complex optimisation problems, which are concerned with optimising a given aspect of a complex system, such as time or energy, are difficult to solve. Often a range of solutions exist, and the difficulty lies in determining which solutions to implement in which part of the system. Within this work, a novel method is developed that allows the solver to overcome the key challenges for these types of problems, which are: defining the system parts (subsystems); minimising model complexity; quantifying solution effectiveness; and identifying relationships between solutions and subsystems. The method is demonstrated through application to the problem of railway traction energy saving. Subsystems are defined using quantified network and service characteristics. For each subsystem, the trends between six key solutions and the key performance indicators are analysed using multivariate data analysis and visualisation techniques. The relationships between subsystems are then explored at system level. The analysis determines the suitable solutions for each type of railway, providing information for operators about which solutions to target. Based on the results, the implementation of permanent magnet motor technology is considered, illustrating that the method is a suitable tool for informing further studies.

The aim of the research was to improve the fundamental understanding of mechanical behaviour of ballast and study the effect of tamping on ballast. The experiments were carried out on scaled railway ballast to eliminate the difficulties associated with testing large particle granular materials. Consideration was given to the gradation, mineralogy and shape during scaling. Particle characterisation work was carried out on scaled and full size ballast using imaging techniques to examine the validity of the use of scaled ballast. Detailed analysis of results is used to quantitatively measure the changes in shape with particle size. The results show measurable differences in particle shape between different particle size intervals. As the differences are small in magnitude, they do not invalidate the use of scaled ballast. Monotonic, cyclic experiments were carried out as part of a laboratory testing programme. Scaled ballast shows generally similar stress strain behaviour to larger granular materials. The friction angle of 40o to 50o for the confining pressure range of 15 kPa to 200 kPa falls within the range of friction angle obtained for full size ballast in the literature. The effect of changing confining pressure during train loading was examined. The results show that the settlement increases and the stiffness reduces when the confining pressure cycles. The effect of principal stress reversal during tamping was examined by an extension stage after the cyclic loading. It is shown that massive settlement occurs after the extension stage during initial cycles and settlement returns back to the pre-extension stage soon under loading. The results evidence the disruption of ballast structure and loss of stiffness due to tamping. Specimens were resin stabilised within the triaxial cell after specific stress paths had been followed. The changes in structure during a specific stress path can be studied by CT examination.

For high-speed trains, aerodynamic noise becomes significant when their speeds exceed 300 km/h and can become predominant at higher speeds. Since the environmental requirements for railway operations will become tighter in the future, it is necessary to understand the aerodynamic noise generation and radiation mechanism from high-speed trains by studying the flow-induced noise characteristics to reduce such environmental impacts. The aim of this thesis is to investigate the flow behaviour and the corresponding aeroacoustic mechanisms from high-speed trains, especially around the bogie regions. Since the prediction of the flow-induced noise in an industrial context is difficult to achieve, this study focuses on scale models with increasing complexity. The aerodynamic and aeroacoustic behaviour of the flow past an isolated wheelset, two tandem wheelsets, a simplified bogie and the bogie inside the cavity with and without the fairing as well as considering the influence of the ground are investigated at a scale 1:10. A two-stage hybrid method is used consisting of computational fluid dynamics and acoustic analogy. The near-field unsteady flow is obtained by solving the Navier-Stokes equations numerically through the delayed detached-eddy simulation and the source data are applied to predict the far-field noise signals using the Ffowcs Williams-Hawkings acoustic analogy. All simulations were run with fully structured meshes generated according to the guidelines based on a grid independence study on a circular cylinder case. Far-field noise radiated from the scale models was measured in an open-jet anechoic wind tunnel. Good agreement is achieved between numerical simulations and experimental measurements for the dominant frequency of tonal noise and the shape of the spectra. Numerical results show that turbulent flow past the isolated wheelset is dominated by three-dimensional vortices. Vortex shedding around the axle is the main reason for the tonal noise generation with the dominant peak related to the vortex shedding frequency. The noise directivity shows a typical dipole pattern. Moreover, for both the tandem-wheelset and the simplified bogie cases, the unsteady flow developed around them is characterized by the turbulent eddies with various scales and orientations including the coherently alternating shedding vortices generated from the upstream axles. The vortices formed from the upstream geometries are convected downstream and impinge on the downstream bodies, generating a turbulent wake behind the objects. Vortex shedding and flow separation as well as interaction around the bodies are the key factors for the aerodynamic noise generation. The radiated tonal noise corresponds to the dominant frequencies of the oscillating lift and drag forces from the geometries. The directivity exhibits a distinct dipole shape for the noise radiated from the upstream wheelset whereas the noise directivity pattern from the downstream wheelset is multi-directional. Compared to the wheelsets, the noise contribution from the bogie frame is relatively small. Furthermore, when the bogie is located inside the bogie cavity, the shear layer developed from the cavity leading edge has a strong interaction with the flow separated from the upstream bogie and cavity walls. Thus a highly irregular and unsteady flow is generated inside the bogie cavity due to the considerably strong flow impingement and interaction occurring there. Unlike the isolated bogie case, noise spectra from the bogie inside the cavity are broadband and a lateral dipole pattern of noise radiation is generated. The noise prediction based on the permeable surface source is formulated and programmed using the convective Ffowcs Williams-Hawkings method. Results show that the bogie fairing is effective in reducing the noise levels in most of the frequency range by mounting a fairing in the bogie area; and for the bogie inside the bogie cavity with the ground underneath, the far-field noise level is increased due to more flow interactions around the geometries and the ground reflection effect.

Ballast is a primary component of the railway track and it has several functions including the ability to resist vertical, lateral and longitudinal forces applied to the sleepers from the train wheels. In response to the stresses induced during a train passage, ballast typically experiences plastic settlement which can reach unacceptable magnitudes. Thus, ballast is the focus of the majority of maintenance and renewal activities. In response to the growing need for resilient track materials (including ballast) to cope with increasing train speed, load and frequency, means of optimizing its performance and minimizing maintenance requirements are required. Ballast improvement techniques, such as the use of geogrids, have attracted a great deal of attention in terms of research, but huge potential for reducing costs through ballast improvement still exist. It has been shown from previous research that the use of randomly oriented fibres in sands can significantly improve their strength. This technique might be used to improve ballast strength and reduce track geometry deterioration. In addition, fibre reinforcements in ballast can potentially provide a new method of reinforcing ballast whilst maintaining the capability of withstanding typical tamping operations which are incompatible with geogrids. However, there is a lack of rigorous scientific understanding of the effects of fibre reinforcements on relatively large aggregates such as railway ballast. This research examines the effect of random fibre inclusions on the packing structure of granular materials (coarse sand and scaled ballast) and describes the physical implications associated with the observed changes. The mechanical properties of fibre reinforced granular materials across different particle sizes and a hypothesis of fibre/particle reinforcement suitable for relatively large particles are presented. An image-based deformation measurement technique has also been used to investigate the effects of fibre reinforcements on the local deformation of triaxial specimens to corroborate the observed mechanical behaviour of the reinforced specimens. Finally, the mechanical behaviour of a fibre reinforced ballast layer below a cyclically loaded railway sleeper was investigated using a full scale laboratory tests.

This is a PhD Thesis by portfolio and is the output of research, development and the practical application of processes for railway track asset management in the UK between 2004 and 2013 and the subsequent development of innovative solutions. There are two major sections to the portfolio; firstly the background, literature review and development phases; and secondly two specific projects. The projects consisted of major works on the UK West Coast Main Line and targeted schemes involving Eurostar and Humberside. The author is a chartered civil engineer and has spent the whole of his career (32 years) in railway civil engineering mainly in design, maintenance and management and culminating in undergraduate and postgraduate teaching. Railway Infrastructure Life Extension is a specialist area that has not been studied before in this depth and was initially related to specific problem solving. However, it is now clearly accepted that UK railway privatisation was a success and after passenger journeys increased by 80% in the period 1996 to 2012, there was substantial strain upon the infrastructure. This portfolio is informed by and considers the current and future challenges faced by railways from a safety, performance and efficiency angle. The study is supported as strategically important work being entirely appropriate and relevant to the industry by the two sponsors, Dr Ilias Oraifige, Senior Academic and Reader at the University of Derby and Ken Mee, Managing Director of Quality and Safety Services Ltd. The term “life extension” was uniquely created and applied to railway infrastructure by the author and his teams during the early phases of this project and became the industry standard phrase for the work involved. The historical background and literature review of the research is included to enable the reader to understand the context of the work undertaken previously where the author acted as the major driver behind the work under industrial conditions commencing in 1997. The author has had a direct involvement in the practical application of the techniques and processes through various senior positions in the UK Rail Industry. The work resulted in testing of equipment in live locations including quantifiable risk assessments and actual benefits to safety, economics and performance. The author held a number of key roles relevant to the study. From 1995 – 2000 he was Regional Director of Balfour Beatty Rail Maintenance and set up the Central Maintenance Group at Sandiacre, Nottinghamshire. This was a team of engineers, supervisors and staff employed to carry out heavy maintenance principally on the Erewash Valley line. From 2000 – 2003 he was Engineering Adviser to the Rail Regulator where he was appointed as the government representative on the Hatfield Recovery Board and sat on various working committees including the Wheel Rail Interface System Authority (WRISA). This was a significant contribution to the recovery of the UK rail system to normal working following the Hatfield Accident. A key contribution during this time was the understanding of the impact of track quality upon asset deterioration. From 2004 – 2007, the author, in his role as General Manager of Carillion Rail Ancillary Projects, was commissioned to set up an organisation to develop and provide innovative and original solutions for life extension and refurbishment of railway track systems in the UK. The principle objective was to build upon previous work done during the final years of the UK contracted-out railway infrastructure maintenance term contracts. The innovations chosen for development were related to delivering economic access to facilitate heavy maintenance and the development of new techniques to extend track life. A number of projects and case studies and their specific solutions are identified and reviewed. Of particular strategic importance is the use of the “Railvac” Swedish ballast removal machine developed in the UK between 2004 and 2012. The culmination of the work is the incorporation of the principles and ideas into the UK National Policy under the ongoing strategy approved by the Office of Rail Regulation for 2014-2019. The author has published a number of papers in support of the thesis which have been presented at conferences in London and Spain.

The European Train Control System (ETCS) as part of the ERTMS (European Rail Traffic Management System) is a train control and automation system, which has been introduced into the UK rail network. The major change with the introduction of the ERTMS has been the shift of the movement authority from signals outside on the tracks to inside the cab, and the introduction of speed profiles that the drivers must adhere to. The introduction of this new system triggered the need to understand its impact on the train driving task and train driver behaviour. In particular, the effect the ERTMS has on drivers’ cognitive strategies and demands. The overall aim of the thesis was to understand the effects of new train control and automation technology on train drivers’ behaviours. The research was conducted, using a mixed methods approach, in the rail environment with train drivers and rail experts. Literature reviews of existing train driving models, train driving research and associated issues of increasing control and automation on human behaviour; were used to provide the theoretical context for the thesis. The literature review highlighted that there was a potential shift in cognitive strategies and demands with the introduction of train automation and control technology. Due to the limited amount of research in train driving on the whole, but also train driving with automation and control technology, the majority of the literature hypothesised the possible impact of the introduction of automation and control technology. An exploratory study of some of the different forms of train driving in the UK, was used to generate insight about train driving with different forms of train technologies and provided the theoretical foundations for the following studies. The emerging cognitive themes also addressed the gap in knowledge about train driving with different forms of technologies. The emerging cognitive themes from this study included route knowledge and memory, monitoring, allocation of attention, anticipation, prioritisation and decision making. A semi-structured interview study with ERTMS drivers, addressed some of the questions raised in the previous study using ERTMS drivers’ subjective experiences. Since the exploratory study, the results demonstrated an adaptation and shift towards acceptance of the system and it also identified some of the driving strategies that had emerged. This chapter investigated drivers’ subjective experience, highlighting high-level strategy changes. A real world exploratory eye-tracking study with both conventional and ERTMS drivers on their normal timetabled routes, provided a wealth of data. The first level of the quantitative eye-tracking analysis, aimed to address the industry question of ‘heads up’ vs. ‘heads up, heads down driving’. It demonstrated a shift of typical visual attentional strategy from monitoring outside on the tracks to speed information inside the cab. Analysis of verbal protocol data collected in the eye-tracking study also provided some rich qualitative data about train driver strategies and demands. Further analyses of the eye-tracking data, identified events where there is a difference in visual behaviour between ERTMS driving and conventional driving, but also between each type of driving and its own baseline data. An expert elicitation workshop with ERTMS human factors experts, was used to generate requirements for a future train driving model. The main findings highlighted that several models are needed to help address some of the issues raised, as they could provide different uses, acting as ‘building blocks’ to the overall picture. Qualitative models can be used to provide the framework and language as a communication tool, whilst more quantitative models can be used to compute error and workload. Models need to be informed by cognitive theory but also focus on the train driving tasks and information used by train drivers. Finally, the studies presented in this thesis were used to develop an integrated human factors model of the influence of train automation and control technology on train driving and guidance was generated for future train driving models for both conventional and ERTMS train driving. The current research has contributed critical knowledge to both the academic literature but also informed human factors practitioners in the rail industry. The thesis has contributed novel understanding about train driving with a control and automation technology, which have already been utilised by the rail industry.

In today’s modern world, society are accustomed to disposable products, temporary services and frequent replacements. The art of maintaining and renewing assets has been somewhat lost. However, in the pursuit of financial performance, comes the need to effectively manage assets. Management of a large portfolio of infrastructure assets is a complex and demanding task for infrastructure owners. Not only is the coordination of a large organisation difficult to align, but every decision is scrutinised by regulatory bodies. For infrastructure portfolio managers, decision support tools are becoming increasingly more useful. This is particularly relevant to railway structures as a result of their diversity and age. A thorough literature review (Chapter 2) is carried out to understand what decision support tools, known as Bridge Management Systems (BMSs), are currently available for railway bridge portfolio managers. The modelling approaches which have been used as the foundation of the BMSs are analysed (Chapter 3). Of these, the most appropriate modelling technique is selected for development of a new approach for a decision support tool. The tool comprises of a number of different modules, each with its own characteristics, data sources and features (Chapter 4). The model is presented, as well as detailed descriptions of each of the modules and how they work. During the literature review stage, a number of studies mentioned that there are external factors that affect deterioration. However, very few studies were able to pinpoint what these factors were, how much they affected deterioration and what the operational, financial and management impacts were. To that effect, a number of different factors were analysed (Chapter 5) to ascertain if they have an effect on bridge deterioration. The key factors were identified and their deterioration profiles incorporated into a probabilistic Petri-Net (PN) model, calibrated with historical data. From these, comparative model outputs pinpointing which factors affect bridge deterioration the most can be computed. Finally, simulations were carried out on the PN model to evaluate which of the factors would have the most financial effect for a transport agency. This allows bridge managers to categorize bridges in different deterioration groups allowing the definition of different optimal inspection and maintenance strategies for each group. This research has also identified that complex models often have a heavy computational burden. A study was carried out to accelerate simulations of PN models with General-Purpose Graphics Processing Units (GPGPUs)(Chapter 7). GPGPUs are composed of many smaller, parallel compute units which has made them ideally suited to highly parallelized computing tasks. The efficiency of different approaches to parallelization of the problem is evaluated. The developed framework is then used on the railway bridge PN model. The results obtained show that this method allows the combination of complex PN modelling with rapid computation in a desktop computer. A final piece of research was undertaken to perform optimisation with the railway bridge PN model (Chapter 8). This study utilised the foundation railway bridge PN model, the Local Environmental Factors (LEFs), the variability factors and the GPGPU acceleration. A Hybrid Multi-Objective Genetic Algorithm (MOGA) approach is accelerated with GPGPUs to find the optimal inspection regime to minimise both the WLCC of railway bridges and the risk of being in a poor condition. The proposed Hybrid Genetic Algorithm (GA) approach is able to accelerate the process by over 30 times compared to the traditional GA approach. The results obtained demonstrate a potential 9% reduction in overall WLCC for UK railway bridges at the same condition as the current industry policy performance. A novel Performance-Based Inspection Planning (PBIP) protocol is introduced to demonstrate where inspections should be focused to monitor bridges in areas susceptible to more severe deterioration whilst easing inspection efforts on those in milder areas of deterioration, improving operational efficiency.

It is important to monitor the wheel-rail friction coefficient in railway vehicles to improve their traction and braking performance as well as to reduce the number of incidents caused by low friction. Model based fault detection and identification (FDI) methods, especially state observers have been commonly used in previous research to monitor the wheel-rail friction. However, the previous methods cannot provide an accurate value of the friction coefficient and few of them have been validated using experiments. A Kalman filter based estimator is proposed in this research project. The developed estimator uses signals from the traction motor and provides a new and more efficient approach to monitoring the condition of the wheel-rail contact condition. A 1/5 scaled test rig has been built to evaluate the developed method. This rig comprises 2 axle-hung induction motors driving both the wheelsets of the bogie through 2 pairs of spur gears. 2 DC generators are used to provide traction load to the rollers through timing pulleys. The motors are independently controlled by 2 inverters. Motor parameters such as voltage, current and speed are measured by the inverters. The speed of the wheel and roller and the output of the DC generator are measured by incremental encoders and Hall-effect current clamps. A LabVIEW code has been designed to process all the collected data and send control commands to the inverters. The communication between the PC and the inverters are realized using the Profibus (Process Field Bus) and the OPC (Object Linking and Embedding (OLE) for Process Control) protocol. 3 different estimators were first developed using computer simulations. Kalman filter and its two nonlinear developments: extended Kalman filter (EKF) and unscented Kalman filter (UKF) have been used in these 3 methods. The results show that the UKF based estimator can provide the best performance in this case. The requirement for measuring the roller speed and the traction load are also studied using the UKF. The results show that it is essential to measure the roller speed but the absence of the traction load measurement does not have significant impact on the estimation accuracy. A re-adhesion control algorithm, which reduces excessive creepage between the wheel and rail, is developed based on the UKF estimator. Accurate monitoring of the friction coefficient helps the traction motor work at its optimum point. As the largest creep force is generated, the braking and accelerating time and distance can be reduced to their minimum values. This controller can also avoid excessive creepage and hence potentially reduce the wear of the wheel and rail. The UKF based estimator development has been evaluated by experiments conducted on the roller rig. Three different friction conditions were tested: base condition without contamination, water contamination and oil contamination. The traction load was varied to cover a large range of creepage. The importance of measuring the roller speed and the traction load was also studied. The UKF based estimator was shown to provide reliable estimation in most of the tested conditions. The experiments also confirm that it is not necessary to measure the traction load and give good agreement with the simulation results. With both the simulation and experiment work, the UKF based estimator has shown its capability of monitoring the wheel-rail friction coefficient.

Regulation requires railway energy absorbers to dissipate the collision energy and to prevent overriding. There is no industrial consensus about which energy absorbing mechanism is the most suitable for the crash conditions present in a collision between railway vehicles. There is scope for improving the existing designs or creating new concepts. The combination of two energy absorption mechanisms, expansion and splitting of cylindrical tubes, was identified as an improved energy absorption mechanism. Quasi-static and dynamic testing of scaled splitting, expansion and expansion splitting (hybrid) tubes was carried out to assess their force, stroke, energy absorption and oblique loading efficiency. In addition, the standard requires a calibrated numerical model of the energy absorber to predict its behaviour. The fracture strain of the tube and the coefficient of friction between the tube and the die are needed to build accurate numerical models. The fracture strain was measured using a Digital Image Correlation technique and a new methodology was developed to overcome its limitations. The inclusion of the fracture strain correctly predicted the deformation of the splitting specimens. The friction coefficient was adjusted until the energy absorption matched that observed during testing. Quasi-static testing showed that the force efficiency was 80%, 100% and 90%, for the splitting, expansion and hybrid tubes respectively. The stroke efficiency was measured as 77%, 44% and 70%, respectively. The energy absorption efficiency of the hybrid tubes was assessed as 11% and 40% higher than that of the splitting and expansion tubes respectively. The testing also showed that the hybrid tubes were more insensitive than the expansion and splitting tubes to the application of oblique loading. More testing may be necessary to confirm this assertion. The results suggest that the hybrid energy absorbing mechanism could become a commercial energy absorber with improved performance over the existing solutions. The validation of the hybrid numerical models showed an accurate prediction of the test results. A full-scale hybrid demonstrator has been tested and a patent of the hybrid concept applied for.

This thesis examines the effect of vehicle dynamics on lateral deterioration of the track alignment. As rail traffic runs along a route, the forces imposed upon the track cause the ballast to settle, and hence the track geometry deteriorates. At a specified value of deterioration the track geometry needs to be restored by tamping or other methods. As the deterioration is mainly in the vertical direction, this aspect has been more widely studied and models have been developed to predict vertical track geometry deterioration. On the other hand, lateral track deterioration is not as well understood, and this thesis aims to fill the gap in this knowledge. However, the understanding of the lateral deterioration mechanisms becomes more important as speed and capacity increase. This thesis describes statistical studies of track lateral deterioration, as well as the development and validation of a vehicle-track lateral dynamic interaction model. This work is undertaken to contribute to the fundamental understanding of the mechanisms of track lateral deterioration, therefore making the effective control and reduction of the lateral deterioration achievable. The statistical analysis provides a better understanding of three aspects of track lateral irregularities, namely: the relationship between vertical and lateral irregularities, the relationship between track curvature and track lateral irregularity and the change in track lateral deterioration over time. The vertical and lateral track irregularity magnitudes are clearly correlated. The track quality in the vertical direction is generally worse than in the lateral direction, however the number of track sections with lateral quality significantly worse than the vertical is non-negligible. The lateral irregularities tend to be larger on curves. It is notable that less than ten percent of the track studied has a constant lateral deterioration due to frequent maintenance activities and bidirectional lateral dynamic forces. Unlike vertical settlement, lateral deterioration develops exponentially in both magnitude and wavelength, and the major influences are found from the irregularities with wavelength longer than 10 m. The change in track lateral irregularity with different curve radii and the lateral deterioration rate are described in separate exponential power functions due to the limitation of the available track data. The parameters for these empirical equations do not remain constant due to the change in track conditions. Current track lateral models mainly focus on lateral failures such as buckling and lateral sliding. The development of lateral track irregularities tends to be studied using representative values of net lateral forces and net L/V (Lateral/Vertical) load ratios. Unlike other track lateral deterioration models, the model developed in this thesis focuses on the development of lateral irregularities based on the dynamic interactions between the vehicles and the track system. This model makes it possible to carry out more integrations and analysis of the track lateral deterioration in a realistic dynamic simulation, using vehicle models, contact conditions, track initial irregularities, and traffic mix more close to the reality. The vehicle-track lateral dynamic interaction model was validated against track geometry data measured on the West Coast Mainline (WCML) in England. It has been found that the model gives a reasonably accurate prediction of the development of lateral track irregularities. However, it also tends to predict a short wavelength deterioration that is not seen in the actual track deterioration. Improvements to the model are suggested by either adding more factors or simplifying the model depending on specific target application. Enhancing the model by including more details, such as longitudinal forces, temperature effect, more layered track systems, uneven track bed conditions and more representative wheel-rail contact conditions etc., may help understand the reason of the additional short wavelength. A sensitivity analysis was performed in order to identify the critical factors that influence lateral track deterioration. The track damage caused by specific vehicles can be controlled by understanding different vehicle dynamics behaviour on a particular track section or route. Vehicles with simple suspension design and heavy axle loads tend to cause more lateral track damage. Within a certain speed range, there will be a critical speed that generates the largest lateral deterioration. Vehicles with different dynamic behaviours can generate a potential offset of the lateral deterioration, so it is possible to design the traffic mix to cancel out the peak deterioration. However, it may not be very practical to redesign the traffic mix due to different traffic requirements. Subsequently, actions can be taken to effectively reduce track lateral deterioration, such as optimise the suspension design, vehicle weight, the selection of an optimal operation speed, and enhance the traffic mix design. As the most important interface between vehicle and track, the wheel-rail contact condition has an extremely large influence on lateral deterioration. Wheel and rail profiles with different wear conditions can cause altered vehicle-track lateral dynamic interaction. It is found that increasingly worn wheel/rail profiles within an acceptable tolerance can effectively reduce the lateral deterioration. Lateral deterioration can also be reduced by increasing all the track stiffness values, damping values and the mass of rails and sleepers, or alternatively, by decreasing the sleeper spacing. The sleeper-ballast interface is found to play the most important role in lateral deterioration. The interfaces between the sleeper and ballast shoulder, crib and base determines the non-linear characteristic such as hysteresis and sliding features. Improving the strength of the sleeper-ballast interface can improve the elastic limits and hysteresis characteristics, hence reducing the lateral deterioration. The findings of the investigation indicate that the model provides in-depth knowledge of the mechanisms influencing lateral deterioration and provides effective solutions with consideration of vehicles, wheel-rail contact and the track system. Further work would include track data with sufficient information in order to develop a more comprehensive empirical model that describes the lateral deterioration, inclusion of more potentially influential factors such as: temperature, ground condition, traffic etc. The model can be improved by taking into account additional factors such as the influence of longitudinal forces from the wheels to the rails, different weather and temperatures, subgrade and ground conditions, etc. The reason for the high frequency noise in the deterioration prediction is not understood yet and it should be discussed in terms of more accurate vehicle simulation results and more comprehensive rail and wheel worn profiles measured on the target track and vehicles. Furthermore, the sleeper-ballast lateral characteristics are not well understood and the previous research in this area is quite limited. To improve on the present work it would be useful to carry out laboratory tests in order to capture more accurately track lateral stiffness and damping values as well as the comprehensive non-linear characteristic of track lateral residual resistance behaviour.