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The osmotic technique in geotechnical testing of unsaturated soils is a promising technique to control soil-water potential. This technique is an alternative to the axis-translation technique. In t...

At first glance the operational performance of ballast appears trivial in its simplicity. However, various mechanisms affect the performance of the ballast both on a macroscopic scale and discrete (mesoscale) particle level. The importance of experimental studies to establish the influence of the granular fabric has been highlighted repeatedly by other researchers. This paper describes a method by which quantitative metrics and statistics can describe the probabilistic response of railway ballast. The measurements were obtained with the installation of a set of customised wireless inertial measurement unit (IMU), referred to as Kli-Pi, in the granular layers of a heavy-haul railway line located in South Africa. The results indicate a complex interaction of displacement and rotation, in all three spatial dimensions. The high-frequency measurements provided approximations of the particle's kinetic and potential energy (mechanical work) in addition to the indirect quantification of changes to the granular fabric. Finally, the descriptive statistics of the mechanical work provided an indirect measure of the confinement and coordination number of the particle, together with supporting evidence of the underlying probabilistic, instead of the expected deterministic response. These results strongly agree with the findings of existing literature that has, to date, been confined to theoretical study.

Centimetre accurate geolocation service is beneficial to a wide range of applications, ranging from sports engineering, civil infrastructure, autonomous vehicles, surveying to digitisation of historically significant structures. Previously, these features were confined to prohibitively expensive commercial hardware, requiring technical knowledge and experience to operate. Continued technological advancements have seen the miniaturisation of electronics and antennas, coupled with an increase in the number and performance of global navigation satellite systems (GNSS) by various nations and organisations, providing global signal coverage. This paper demonstrates a low-cost, mobile, real-time kinematic (RTK) geolocation service for engineering and research applications, fabricated from components readily available from commercial suppliers. This solution, consisting of a mobile RTK base station and RTK rover, provides centimetre-accuracy performance up to a distance of 15 km away from the base station. Correction data is transmitted over the internet using free and open software solutions. The small footprint of both the RTK base station and RTK rover, provides versatile applications even in remote locations. The performance of the geolocation service is validated using field experiments, comparing measurements against state-of-the-art photogrammetry, light detection and ranging (LiDAR) and digital level measurement technologies. The authors encourage the adoption of the RTK geolocation solution based on the calibrated results.

Volumetric water content (VWC) and matric suction vary temporally in the foundation layers of pavements and railways due to various influencing environmental factors. The resilient and permanent deformation behaviors of railway foundation materials are strongly linked to the suction within the soil, reinforcing the need for the measurement thereof. This paper reports on the installation of VWC sensors, tensiometers and fixed-matrix soil-water suction sensors in different configurations within the foundation layers of a new 26 tonne/axle railway line near Ermelo in South Africa. Local weather data was recorded using a weather station at the site. The VWC sensors and the fixed-matrix soil-water suction sensors also monitored soil layer temperature. The measurement techniques used are critically compared with regard to their ability to respond to weather events. Practical aspects pertaining to the installation procedures and maintenance required for the different techniques are also reported. It was found that tensiometers require careful consideration to ensure pore-water continuity when installed in the field. Nonetheless, tensiometers were the most reliable and accurate form of measurement in this study. The use of VWC sensors to infer suction in silica flour is a novel idea. However, this method showed limited success in this study. Fixed-matrix soil–water suction sensors provided the best long-term stability and ease of installation. However, the accuracy of these sensors requires further investigation.

Laboratory tests on ballast give insight into the behaviour and performance of the ballast layer under passenger and heavy-haul traffic. It is important, however, to ensure that the simulation of train loads on the ballast layer in the laboratory represents in-situ loading conditions. Furthermore, the provision of ballast lateral confinement during laboratory tests should model the confinement along the track. With adequate, representative loading patterns and boundary conditions executed during laboratory tests on ballast, the overall response and performance of the ballast layer can be estimated and predicted more accurately. This gives an indication of an ideal response of the ballast layer in the field, as well as its impact on track structure deterioration. The objective of this study was to develop suitable cyclic loading and boundary conditions for ballast box tests in the laboratory to represent similar conditions in the field. By conducting box tests, the ballast deformation results revealed the suitable loading pattern that produced a similar rate of ballast strain accumulation as the Field Loading (FL) pattern. Furthermore, boundary condition results showed that decreasing the Level of Lateral Confinement (LoLC) increased the permanent deformation of the ballast layer and the breakage of ballast. The laboratory loading pattern developed in this research, as well as comparable laboratory and field boundary conditions, could provide accurate predictions of the long-term behaviour of ballast and support the planning for subsequent ballast maintenance interventions based on realistic and accurate laboratory test results.

Railway wheel squeal is an unresolved noise pandemic facing the railway industry. Wheel squeal results from frictional self-excited vibration occurring in the wheel-rail contact. Solving the problem of squeal requires researchers to work towards a squeal model that can predict squeal wholly and in every situation. This will allow for squeal to be resolved during the design stages. The current research presents a frequency domain model for the excitation of squeal due to longitudinal creepage with rising, constant and falling friction. In this model the time varying part of the longitudinal creep force is modelled as a feedback loop and tested for stability with the Nyquist criterion. Crucial to the instability is modelling the dynamics of a wheel taking into consideration the moving load nature of the rotating wheel. If wheel rotation is accounted for in the model, modes in a doublet can become unstable through mode-coupling in the presence of large longitudinal creepage. The results of the model provide good agreement with that of squeal occurring on-track. Positive flow of energy for the modelled case of squeal results from the dynamic friction and normal forces being in phase with one another as well as the friction force causing normal displacement at the wheel-rail contact that is in phase with the normal displacement that caused the normal force in the first place. This closed phase loop causes positive interference of the normal vibration in the wheel-rail contact and allows the vibration amplitude to grow. Extending the model to include lateral creepage shows that the vibration of the wheel-rail contact can be unstable due to unsteady longitudinal creepage for more directions of the resulting creep force compared to unsteady lateral creepage in a case with constant friction.

Changing climatic conditions worldwide are causing changes in moisture conditions of railway formations and slopes, thereby either strengthening or weakening them. Current railway formation design methods do not take into account the changing moisture conditions over the predicted life of a railway formation. These changes in soil strength are due to the influence of soil suctions. The basic principles of unsaturated soil mechanics are well established in the field of geotechnics, and this study joins an international body of work that seeks to apply unsaturated soil theory to the field of railway and pavement formation materials. This study comprised box testing of subgrade and subballast formation materials at different moisture contents to demonstrate the behaviour of these two materials relative to each other. The formation models were instrumented with tensiometers to monitor the effect of cyclic loading and loading frequency on material behaviour and soil suction under typical heavy haul loading (26 tonne/axle). The study also investigated the evolution of suctions present in railway formation materials as well as practical aspects relating to suction measurement under cyclic loading conditions. Suctions were successfully measured in both the subgrade and subballast materials subjected to cyclic loading, demonstrating the different suction magnitudes generated by the materials under typical railway formation conditions. The well-drained subballast material was found to generate low magnitudes of suction over a large range of degrees of saturation (1 kPa – 15 kPa), while the less well-drained subgrade material was found to generate a greater range of suctions (1 kPa – 95 kPa) with a smaller variation in the degree of saturation. The deformability of the subgrade material depended to a greater on the moisture state and soil suctions compared to the subballast material and showed a large variation in deformability as a function of its moisture state. At its wettest, the subgrade material experienced deformation exceeding the allowable failure limit, while the subgrade material deformed less than the subballast material at its driest. The subballast deformation was significantly affected by the loading frequency and less by its moisture state due to the low suctions present. The findings of this study have practical implications for both in-situ and laboratory testing of railway formation materials and emphasized the importance of the moisture state of the formation during the railway service life.

The measurement of track substructure deflections is an important parameter for the determination of structural capacity, identification of track problem areas and evaluation of overall track condition. This paper describes a mechanistic-empirical method by which elastic moduli of railway formation layers can be determined from substructure deflections under transient train loading. The method was founded on surface deflection theory from falling weight deflectometer (FWD) analysis. Finite element (mechanistic) analysis and field data (empirical) from railway substructure deflections obtained from multi-depth deflectometers (MDDs) were used to assess the validity of the mechanistic-empirical method by comparing measured and modelled railway substructure responses. The results indicate that substructure deflections and stresses are affected by the complex superposition of different bogie loading configurations on a particular superstructure. The load distribution in the railway substructure does not follow a 45° influence line as commonly assumed in surface deflection theory. On the contrary, railway equilibrium influence lines are significantly influenced by the structural capacity of the formation layers and in-situ subgrade. The predictions offered by this method strongly agree with the long-term formation peak strains measured by MDDs and this method was determined suitable for evaluation of formation structural capacity due to good agreement between measured and estimated elastic moduli of formation layers.

Traffic analysis is dependent on reliable and accurate datasets that quantify the vehicle composition, speed and traffic density over a long period of time. The utilisation of big data is required if equitable and efficient transportation networks are to be realised for smart, interconnected cities of the future. The rapid and widespread adoption of digital twins, IoT (Internet of Things), artificial intelligence and mini edge computing technologies serve as the catalyst to rapidly develop and deploy smart systems for real-time data acquisition of traffic in and around urban and metropolitan areas. This paper presents a proof of concept of a mini edge computing platform for real-time edge processing, which serves as a digital twin of a multi-lane freeway located in Pretoria, South Africa. Video data acquired from an Unmanned Aerial Vehicle (UAV) is processed using a neural network architecture designed for real-time object detection tracking of vehicles. The implementation successfully counted vehicles (cars and trucks) together with an estimation of the speed of each detected vehicle. These results compare favourably to the ground truth data with vehicle counting accuracies of 5% realised. Detection of sparse motorcycles and pedestrians were less than optimal. This proof of concept can be easily scaled and deployed over a wide geographic area. Integration of these cyber-physical assets can be incorporated into existing video monitoring systems or fused with optical sensors as a single data acquisition system.

A high-resolution dataset of digitally scanned railway ballast (HRSBallast) is presented, consisting of 108 individual, digitised samples. The ballast samples were sourced from both a railway test track section located on a heavy haul coal export line in South Africa and a local quarry. The sampled ballast from the field installation represent angular, semi-angular and rounded geometric features depending on the sampled location. The fresh ballast sourced from the quarry was iteratively tested using a hydraulic actuator in a small-scale box test which forms part of a separate research project. The ballast samples were scanned before and after every test to ascertain the changes in geometry, in addition to the loss of material due to attrition. The field and laboratory samples were digitised using a high-resolution, commercial (Visual Simultaneous Localization and Mapping) VSLAM-based scanner with a 40-micrometre accuracy. Samples which were fractured by the hydraulic actuator are also included in the dataset. HRSBallast serves as a reference dataset for granular media (GM) simulations utilizing DEM (discrete element method), degradation or wear modelling, digital assets for the creation of synthetic datasets for deep learning applications, embedded railway instrumentation and video games requiring high-resolution geometry.

The problematic nature of the relationship indicative/imperative in Pauline ethics: certain aspects of the discussion since 1924 Bultmann (1924) has pointed to the crucial importance of the relationship between the indicative in order to understand Pauline ethics. Viewpoints regarding this relationship have been debated extensively in studies related to Pauline ethics. A survey of the current debate has led to the conclusion that the relationship between the indicative and the imperative - which is basic to Pauline ethics - is closely connected to themes central to his theology: his message of justification, faith, and the gospel as the power of God, his eschatology, Christology and pneumatology.

Transportation foundations around the world exist predominantly in an unsaturated state. Support for the adoption of unsaturated soil mechanics in routine geotechnical engineering is ever-increasing. However, the measurement and characterization of soil suction is a potentially significant barrier thereto. To this end, the efficacy of various measurement techniques was investigated, with the aim to characterize the temporal variation in soil suction and temperature within the formation layers of a heavy haul railway formation. Tensiometers, fixed-matrix soil-water matric potential sensors and capacitance-type volumetric water content sensors were installed within the formation layers of a railway track and monitored for a period of 18 months. The average suction measured over the observational period was 25.6, 12.7, 3.5 and 4.2 kPa for the special subballast, subballast and two subgrade layers respectively. Suctions reached a minimum of ≈ 0 kPa at the end of the rainfall season across all layers and reached a maximum, ranging between 10 and 60 kPa across all layers at the end of the dry season. Soil temperatures for the observational period varied between 10 and 22 °C and displayed seasonality in-phase with the monitored air temperatures. The special subballast layer (uppermost layer) showed the greatest variation in both suction and temperature and is the layer which experienced the greatest stress changes as a result of seasonal variations in rainfall and air temperature.

A Perfectly Accurate, Synthetic dataset featuring a virtual railway EnVironment for Multi-View Stereopsis (RailEnV-PASMVS) is presented, consisting of 40 scenes and 79,800 renderings together with ground truth depth maps, extrinsic and intrinsic camera parameters, pseudo-geolocation metadata and binary segmentation masks of all the track components. Every scene is rendered from a set of 3 cameras, each positioned relative to the track for optimal 3D reconstruction of the rail profile. The set of cameras is translated across the 100 m length of tangent (straight) track to yield a total of 1995 camera views. Photorealistic lighting of each of the 40 scenes is achieved with the implementation of high-definition, high dynamic range (HDR) environmental textures. Additional variation is introduced in the form of camera focal lengths, camera location and rotation parameters and shader modifications for materials. Representative track geometry provides random and unique vertical alignment data for the rail profile for every scene. This primary, synthetic dataset is augmented by a smaller photograph collection consisting of 320 annotated photographs for improved semantic segmentation performance. The combination of diffuse and specular properties increases the ambiguity and complexity of the data distribution. RailEnV-PASMVS represents an application specific dataset for railway engineering, against the backdrop of existing datasets available in the field of computer vision, providing the precision required for novel research applications in the field of transportation engineering. The novelty of the RailEnV-PASMVS dataset is demonstrated with two use cases, resolving shortcomings of the existing PASMVS dataset., Graphical abstract Image, graphical abstract

The research described in this paper is based on an experiment which involved running a test train through a curve at various speeds, changing the cant of the curve by tamping and repeating the train runs. The cant was changed due to high wheel wear rates. The curve already had a cant deficiency, and this cant deficiency was subsequently increased by reducing the curve's cant. Assessing the before and after tamping test data validated the existence of the expected relationships between the vertical and lateral rail forces, the speed and the cant. The change in cant had a minimal effect on the magnitude of the vertical forces, although a transfer of loading between the high and low legs did occur. The theory indicates that the 14% reduction in cant in this curve, given all of the other curve characteristics, should have resulted in an increase in the lateral forces. There was, however, a roughly 50% reduction in the maximum lateral forces, after the cant had been reduced, which can be explained from a train dynamics point of view. In addition, there was an increase in safety, due to a reduced derailment ratio at this curve's normal operating speed of 85 km/h. It is not unreasonable to presume that a 50% reduction in the maximum lateral forces could lead to a halving of the wear rate of the rail and wheels in this curve, with similar results to be expected in other curves on the rail network.

The need for decision support systems to guide maintenance and renewal decisions for infrastructure is growing due to tighter budget requirements and the concurrent need to satisfy reliability, availability and safety requirements. The rail of the railway track is one of the most important components of the entire track structure and can significantly influence maintenance costs throughout the life cycle of the track. Estimation of life cycle cost is a popular decision support system. A calculated life cycle cost has inherent uncertainty associated with the reliability of the input data used in such a model. A stochastic life cycle cost model was developed for the rail of the railway track incorporating imperfect inspections. The model was implemented using Monte Carlo simulation in order to allow quantification of the associated uncertainty within the life cycle cost calculated. For a given set of conditions, an optimal renewal tonnage exists at which the rail should be renewed in order to minimise the mean life cycle cost. The optimal renewal tonnage and minimum attainable mean life cycle cost are dependent on the length of inspection interval, weld type used for maintenance as well as the cost of maintenance and inspection activities. It was found that the distribution of life cycle cost for a fixed renewal tonnage followed a log-normal probability distribution. The standard deviation of this distribution can be used as a metric to quantify uncertainty. Uncertainty increases with an increase in the length of inspection interval for a fixed rail renewal tonnage. With all other conditions fixed, it was found that the uncertainty in life cycle cost increases with an increase in the rail renewal tonnage. The relative contribution of uncertainty of the planned and unplanned maintenance costs towards the uncertainty in total life cycle cost was found to be dependent on the length of inspection interval.

As train speeds and heavy haul axle loads constantly increase due to market demands, so do the stresses and strains experienced by track structures. This is especially true for track transitions that generate high dynamic forces on both the track and vehicles because of poor vertical track geometry and/or differing track stiffness values on either side of the track transition. Reducing differential settlement between the two track structures at a track transition is one method of improving the life of the track, and increasing maintenance intervals. In this study, rigid polyurethane foam was used to reinforce ballast. Tests were conducted using a dynamic hydraulic load frame and a single sleeper in a large ballast box subjected to heavy haul axle loads. Unreinforced, reinforced and 50% reinforced ballast layers of 300 mm depth were tested to approximately 5 000 000 load cycles. The results showed that rigid polyurethane foam-reinforced ballast exhibited in the order of 60% less settlement for a fully reinforced layer, and 42% less settlement for a half reinforced layer. The use of rigid polyurethane foam (RPF) to reinforce ballast has a number of benefits that could result in better track geometry and longer maintenance cycles, in turn resulting in lower life cycle costs.

The heavy haul coal line of the South African railway network is facing a problem where ballast particles are becoming rounded, negatively affecting performance and thus leading to shorter planned maintenance cycles. This has been attributed to the lack of a more scientific way of evaluating the ballast shape properties. The objective of this paper is to investigate the effect of ballast particle roundness on shear strength properties of five ballast materials used on the Transnet Freight Rail heavy haul coal line. A river pebble sample was included in the study as the reference material for extremely rounded ballast. All six materials were scanned in a 3-D laser scanning system to develop models of the ballast and the river pebble particles. Based on the laser scanner results, a new empirical model has been developed to determine the surface area of ballast materials. The surface area values were further used to develop a chart to assess different particle shapes with varying degrees of roundness. Triaxial tests were conducted to determine the effect of the roundness on the shear strength properties of the materials. A Mohr-Coulomb failure model was successfully developed from the results to represent individual materials tested. The overall results show that the angle of internal friction increases with roundness of the sample greater than 0.8. More rounded particles have values between 0.6 and 0.7, whereas less rounded particles have values between 0.8 and 1.3. The outcomes of this study would assist with quality assessments in the field and whether or not a degraded ballast track layer has to be replaced.

The benefits of increased axle loading in the railway industry are well-appreciated to such an extent that increased axle loading has become a themed topic of interest across all disciplines of railway engineering. However, it remains important to understand the engineering behavior and performance of each track component under increased axle loading. This study was particularly interested in the behavior of railway foundation materials under increased axle loading, starting from a base load of 20 tonnes per axle for general freight to increased loads of 26, 30, 32.5 and 40 tonnes per axle for heavy haul. The methodology followed involved formulation of a theoretical model for analyses, characterization of the cyclic railway loading via finite element modelling, experimental laboratory work using a cyclic triaxial apparatus followed by detailed analyses, interpretation and discussion of the test results. Based on the test results from the monotonic and cyclic loading, it was found that the critical state line was related to the various phase transitions in soil behavior and the resilient strain was found to be inversely related to the permanent strain. Stress states slightly above the critical state line resulted in a double-phase transition in soil behavior from dilation to contraction and then work softening with cyclic mobility. Stress states on the critical state line resulted in a single-phase transition in soil behavior from dilation to contraction with a combination of cyclic mobility and shakedown. Stress states below the critical state line resulted in a no-phase transition in soil behavior accompanied by dilation with shakedown. In relation to the effect of increased axle loading on saturated heavily overconsolidated railway materials, it was therefore concluded that resilience can be characterized by a no-phase transition predominated by linear permanent deformations and shakedown behavior while failure is characterized by a double-phase transition predominated by exponential permanent deformations and cyclic mobility behavior.

A Perfectly Accurate, Synthetic dataset for Multi-View Stereopsis (PASMVS) is presented, consisting of 400 scenes and 18,000 model renderings together with ground truth depth maps, camera intrinsic and extrinsic parameters, and binary segmentation masks. Every scene is rendered from 45 different camera views in a circular pattern, using Blender's path-tracing rendering engine. Every scene is composed from a unique combination of two camera focal lengths, four 3D models of varying geometrical complexity, five high definition, high dynamic range (HDR) environmental textures to replicate photorealistic lighting conditions and ten materials. The material properties are primarily specular, with a selection of more diffuse materials for reference. The combination of highly specular and diffuse material properties increases the reconstruction ambiguity and complexity for MVS reconstruction algorithms and pipelines, and more recently, state-of-the-art architectures based on neural network implementations. PASMVS serves as an addition to the wide spectrum of available image datasets employed in computer vision research, improving the precision required for novel research applications.

The relatively long life cycle of railway infrastructure means that maintenance and renewal decisions significantly influence the total life cycle cost (LCC) associated with the infrastructure. A decision support tool such as life cycle costing assists infrastructure managers in making maintenance and renewal decisions. A shift from qualitative to quantitative decision making is possible using decision support tools and modelling approaches based on appropriate data. Most LCC maintenance models in the literature are deterministic in nature. However, there is inherent uncertainty present within the reliability and maintainability (R&M) parameters. The uncertainty within the R&M parameters can be characterised through appropriate statistical distributions or using bootstrapping in conjunction with available data. A maintenance modelling approach based on stochastic methods and Monte Carlo simulation is presented in this paper with specific attention to a model developed for the rail component. The proposed model allows quantification of inherent uncertainty within the calculated LCC which is coupled to the uncertainty within the input R&M parameters. This modelling approach is flexible in nature and supports the use of large input data sets, capturing variability within the real-world situation of maintenance management. The flexibility of the modelling approach is demonstrated using an example which incorporates risk to assist an infrastructure manager in deciding whether to use flash butt or alumino-thermic welding during rail maintenance.

Tonal squeal noise (i.e. the high-amplitude singing of a railway wheel with pure tone components) is emitted by some trailing inner wagon wheels on heavy haul trains traversing 1000 m radius curves on the iron ore export line in South Africa. Field measurements have shown that the trailing inner wheels that squeal are subject to predominantly longitudinal creepage with little-to-no lateral creepage. The longitudinal creepage acting at the contact of the squealing wheels exceeds 1%, which supports the likelihood of creep saturation and subsequent squealing due to unsteady longitudinal creepage in the large-radius curves. Experimental modal analysis of the wheel types identified to be relevant to squeal has revealed that for each unstable frequency, two eigenmodes are likely to be important: one that has a large mode shape component at the wheel–rail contact in the circumferential direction and another that has a large mode shape component at the wheel–rail contact in the radial direction. A frictional self-excitation mechanism based on mode-coupling is favoured as being responsible for squeal excited in large-radius curves.

The rational design of a substructure to support a rail track requires an estimation of the stiffness value of the formation on which it is to be built. Stiffness values derived from back-analyses of deformations of the ground beneath the track have been found by the authors to be much higher than those predicted from laboratory element testing on saturated specimens. This may be because of differences in compaction between field and laboratory, or because suctions created by lack of saturation play a key role in controlling stiffness, and therefore the performance of the track when in use. To test the latter hypothesis a laboratory study has been carried out on material representative of that found in South African railway formations. This was tested at constant dry density and various water contents, with matric suctions determined using different established techniques, and very-small-strain stiffness levels obtained from resonant column testing. A suction stress characteristic curve was developed to identify the contribution of suction to the overall effective stress for this material. The results show that suction can indeed be an important contributing factor to the magnitude of stiffness. For material tested at constant dry density, the stiffness initially increases with reducing compaction water content, and therefore with increasing suction. It subsequently reduces back towards the saturated value as the compaction water content approaches zero, even though the matric suction continues to increase. The relative increase in very-small-strain stiffness due to suction depends, to a large extent, on the net normal stress during the stiffness measurement. The effect of matric suction is proportionately greatest at the low net normal stress levels that apply for shallow infrastructures such as rail formations. Also, the operational stiffness depends not only on the current water content (and therefore suction), but also on the water content at which the material has been compacted.

Continuous welded rail (CWR) is a fundamental component of any modern track structure and has several advantages over former types of rail joining processes. The reduction in maintenance and related costs has become the most attractive property of CWR although careful monitoring and maintenance of CWR is essential to ensure safe train operations. Management of the stress-free temperature (SFT) of any section of CWR in order to prevent rail breaks and lateral buckling that could lead to derailments is a vital duty of the track maintenance team. Variations in the SFT are influenced by a number of external factors. This paper describes experimental field and laboratory tests carried out to investigate to what extent the fastening strength influences the variation in SFT in CWR track on Fist fastenings and two types of pads. The research established a nonlinear relationship between clamping force and rail movement through the fasteners as well as a strongly linear relationship between clamping force and the variation in SFT. It is also demonstrated that although the friction coefficient of the pad has an influence on rail movement through the fastener, the primary factor influencing SFT variations is the clip force. This paper concludes by quantifying the relationship between clamping force and the expected variation in SFT with clear guidelines on the management of the SFT in CWR.

Under-sleeper pads (USPs), typically made from polyurethane, are used by railways in certain parts of the world to reduce ballast settlement and consequently lengthen the ballast tamping cycle. The rationale behind this relatively new addition to the conventional ballasted track structure is that the pad increases the contact area between the angular ballast particles and the underside of the concrete sleeper, with the effect that ballast breakdown and total track settlement are reduced. This paper describes two experiments on the effects of USPs on four aspects of sleeper-ballast interaction, namely contact area, contact pressure, ballast settlement and ballast breakdown. Static and dynamic tests up to 1 million loading cycles were performed under controlled laboratory conditions on concrete sleepers with and without USPs. Sophisticated pressure sensors revealed an increase in contact area from 12% to 35% for static loading tests, and from 8% to 20% for dynamic tests, with a resulting 70% reduction in contact pressure. In addition, a 44% reduction in ballast settlement and a 23% reduction in ballast breakdown were achieved by the introduction of USPs. In conclusion it is argued that the introduction of USPs specifically on heavy-haul lines would offer significant advantages with respect to ballast settlement and breakdown. These advantages are most likely to lengthen general ballast tamping and screening cycles, resulting in significant life cycle cost savings.

This paper presents the results of a detailed investigation into the ground deformations that occur under a railway line during the passage of a train. Four horizontal boreholes were installed at different depths below a ballasted railway track. Ground deformations were measured using geophones at set distances from the centreline of the track within each borehole. The results show vertical displacements reducing with depth, from a maximum at the sleeper. Sleeper displacements are dominated by pairs of bogies at the ends of adjacent wagons (which have a frequency of loading 1 Hz), although the effects of individual bogies (2 Hz) and axles (6 Hz) are also apparent. Higher loading frequencies attenuate with depth so that at a depth of 0·780 m below the sleeper soffit no axles are visible within the displacement data and by a depth of 1·98 m only the combined effect of pairs of adjacent bogies is apparent. In contrast, longitudinal horizontal motion is greatest at a depth of 0·78 m below the sleeper soffit, and the longitudinal horizontal displacements at the sleeper and at a depth of 0·78 m are dominated by the individual axles (∼6 Hz). By a depth of 1·98 m, the longitudinal horizontal motion is dominated by the bogie pairs. A dynamic linear-elastic two-dimensional finite element model was developed and validated using the measured displacements.

Transnet Freight Rail monitors the behaviour of a new track foundation, constructed in 2004, on the South African Coal Line. This site forms part of a major rehabilitation project, aimed at increasing the capacity of the line to sustain future growth in annual tonnage. Sophisticated instrumentation is used to measure resilient and permanent deformation of the track foundation. Preliminary results of this research were published shortly after the construction of the new track foundation. Results of the permanent deformation, gathered over a period of 5 years, are now presented to provide new insight into the long-term behaviour of track foundations. Permanent deformation measurements are used to calculate the expected design life of a track foundation. The results are used to predict permanent deformation and ultimately the design life of the track foundation under heavy haul loading conditions. The research provides a scientific basis for planning foundation rehabilitation in the light of sustained capital expansion and projected tonnage increase on the Coal Line and other heavy haul lines.

A realistic assessment of the whole life cost of rail track foundations requires analysis of the effects of the repeated loadings applied by trains. This paper reports the effects of principal stress rotation (PSR) during cyclic loading on the permanent deformations measured in a series of hollow cylinder tests. The tests were carried out on a number of reconstituted soils selected in order to simulate foundation materials on an existing heavy haul railway line. Typical loadings and track geometry together with dynamic finite-element analyses were used to define representative stress changes to be applied to these soils, which were then tested with and without principal stress rotation during loading. It is shown that principal stress rotation has a significant and deleterious impact on permanent deformation of some materials. Therefore, it is concluded that cyclic triaxial testing, which cannot impose principal stress rotation, will not necessarily give good estimates of the long-term performance of rail track foundations. As PSR cannot be ignored when evaluating permanent displacements of rail track foundations, the use of more appropriate (realistic) testing methods such as the cyclic hollow cylinder or the cyclic simple shear apparatus is required.

The design of a railway track substructure requires a realistic understanding of the resilient behavior of the underlying track foundation materials, namely, the subballast and subgrade layers. Currently, the best available method of characterizing the resilient behavior of track foundation materials is through the execution of cyclic triaxial tests, although these do not have the ability to impose principal stress rotation (PSR) on test specimens. A previous paper by the authors demonstrated that PSR increases the rate of permanent strain development. This paper reports on the effects of PSR on the resilient behavior of track foundation materials. Four different reconstituted soils selected to represent typical track foundation materials were subjected to undrained cyclic and torsional shear tests in a hollow-cylinder apparatus. It was established that PSR reduces the resilient modulus of the materials compared with cyclic loading without PSR. The effects of PSR as a function of clay content, overconsolidation ratio (OCR), and consolidation regime (isotropic or anisotropic) were also investigated.

The Old Testament background for understanding the covenant motif in the New Testament - Part 1: Description of the question and analysis of the meaning of the word בְדִית* The concept of the covenant has once again become extremely relevant within the context of the debate on the relationship between the Old and New Testaments, as well as within the context, of the quest for determining the relationship between the Church and Israel. In this article the meaning of the word בְדִית* is discussed. It is argued that this concept has to be understood within the context of the semantic field in which it is used in the Old Testament. Certain facets of meaning in specific contexts in which בְדִית* occurs, are accentuated and discussed. The Septuagint's translation of בְדִית*, as well as the translation of בְדִית* in the Vulgate and in some modem translations, is also discussed briefly.

The Old Testament background for understanding the covenant motif in the New Testament - Part 2: Overview of the history of research and conclusion In this article an overview is given of the function of the concept 'covenant' as it is employed in a number of prominent Old Testament theologies in the post-Eichrodt period, namely that of Von Rad, Zimmerli, Clements, and Westermann. The important contribution by Lothar Perlitt, as well as the recent publication by Rendtorff on the covenant formula is also discussed. Despite certain points of criticism which can be levelled against their comparison between the notion of covenant in the Old Testament and that found in Ancient Near Eastern treaties, the important research of Baltzer and Mendenhall still needs to be considered seriously. Before a conclusion is drawn, the reader is pointed to the importance of the promise of a new covenant within the context of the Old Testament.

The letters to the Colossians and Ephesians enrich the understanding of the New Testament message of salvation in unique ways. The world, once considered to be a well ordered cosmos, had come to be apprehended as a cosmic prison superintended by hostile spiritual presences. In asserting the supremacy of Christ, the letter to the Colossians turns the interest of its readers away from cosmological speculation and fear to the centrality of forgiveness and salvation. The letter to the Ephesians sets the power of God's salvation over and against the cosmic powers and emphasizes that believers have been resurrected and exalted with Christ to a position of power and authority far superior to the hostile cosmic powers. The message of salvation in both these letters addresses the "Weltangst" of a Hellenistic world in a decisive and comforting way.Keywords: Colossians; cosmological speculation; Ephesians; Hellenistic world; New Testament; salvation

Points of departure for a theology of the New Testament: Oscar Cullmann and Leonhard Goppelt Both Cullmann and Goppelt offer alternative positions to an existential approach to New Testament theology. After a consideration of Oscar Cullmann’s position in the history of New Testament theology, special attention is given to his concept of salvation history, as well as a critical evaluation of this concept. Goppelt associates himself with the hermeneutical point of departure of Cullmann and Von Rad. Salvation history is, however, filled with new content through reflection on the earthly Jesus. Goppelt’s starting point for a theology of the New Testament is not found in a general easier ‘kerygma’, but in the unfolding of Jesus’ words and deeds.

In this paper some results on finite direct sums of torsion-free abelian groups of finite rank whose endomorphism rings are principal ideal domains are presented. For example, Theorem 1 states the following. Suppose , where the endomorphism ring of each Bi. is a principal ideal domain and each Bi is isomorphic to a group in a semirigid system. If , then E has a summand of rank at least r, which is isomorphic to a direct sum of a subset of the Bi.