The profound value of wayside monitoring in helping safeguard the RAMS of railway operations is undeniable. However, despite significant investments by the rail industry, the efficiency and reliability of wayside monitoring have not reached the desired level. Structural deterioration of the rail infrastructure and rolling stock faults still remain a significant problem which needs to be addressed as traffic density, train speeds and axle loads increase in rail networks around the world. The main objectives of this study were to develop and evaluate an advanced wayside monitoring system based on acoustic emission and vibration analysis that can detect various types of axle bearing defects in rolling stock and structural deterioration in cast manganese crossings. The potential architecture for different levels of system correlation has been proposed which can be further integrated with customised monitoring system. A novel signal processing technique based on spectral coherence has been developed. This particular method is based on the identification of suitable templates containing features of interest. It also features in identifying the severity of the defect. In addition, a suitable approach for data fusion from various sensors has been investigated. Successful tests have been carried out under simulated conditions and in the UK network.

It is important to have consistent ballast testing methods that provide results reflecting the performance of different ballast materials in the railway trackbed. In this research, extensive laboratory tests were conducted to investigate the correlation between simple ballast index tests, and box tests simulating ballast field loading conditions in a simplified and controlled manner. In the box test, a sleeper load of 40kN was applied to a simulated sleeper on the top of a sample of ballast in a box of dimensions 700x300x450mm. The ballast was tamped using a Kango hammer which caused particles to rearrange as the level of the sleeper was raised. The ballast tests investigated in this project are those ballast tests specified in the Railtrack Line Specification (RT/CE/S/006 Issue 3, 2000), in addition to single particle crushing tests, oedometer tests, petrographic analysis, and box tests. It was found that there was some correlation between the single particle crushing tests, oedometer tests, box tests and petrographic analysis. One of the current ballast tests, namely the Aggregate Crushing Value (ACV) test, which is analogous to the oedometer test, is not appropriate because the ACV test uses 10-14mm ballast particles, and there is a size effect on the strength of ballast and different ballasts have different size effects. However, if an oedometer test is used on track ballast, the results correlate better with ballast field performance as simulated in the box tests. Six ballasts were tested: A, B, C, D, E and F (mineralogy of these ballasts can be found in the appendix). The aim was to examine the relative performance of these ballasts and to establish which index tests were most indicative of performance in the box test. Simple index tests were performed on each of the ballasts, whilst box tests were only performed on ballasts A, B, C and D. The box tests were generally performed wet by adding a known volume of water at each tamp. For ballast A, controlled tests were also performed on dry ballast, and tests involving traffic loading only and tamping only were also conducted. A box test on 10-14mm ballast A was also conducted to investigate the size effect on ballast behaviour in the box. The Wet Attrition Value (WAV), Los Angeles Abrasion (LAA), and Micro-Deval Attrition (MDA) seem to be suitable parameters to indicate ballast performance in the box test. However, this is considered to be due to the rearrangement of particles in the box test caused by the simulated tamping. In addition to the laboratory tests, the application of discrete element program PFC3D (Itasca Consulting Group, Inc., 1999) in simulating ballast behaviour was also investigated. Single particle crushing test was simulated to produce crushable agglomerates with a distribution of strengths of ballast A. These agglomerates were then used to simulate the oedometer test. The resulting normal compression line was compared with that for real oedometer tests: discrepancies can be attributed to the simplified geometry of the agglomerates. Due to the high computational time in simulating a box test with crushable agglomerates, uncrushable spherical balls and uncrushable angular agglomerates were used to represent individual ballast particles in the box. Important aspects of ballast behaviour under repeated loading, namely resilient and permanent deformation, were studied. It was found that the box test on uncrushable angular agglomerates give less permanent deformation compared with the test on spherical balls, because of the additional resistance provided by the irregular shape of the agglomerates.

The only commercially operating magnetically levitated (maglev) transport system in the world is the link between Birmingham International Airport and the National Exhibition Centre. Comparative financial analysis for this route showed that the construction costs for both wheeled and maglev systems were similar and that the cost of the guideway accounted for over 70% of the total. In part this was because the guideway was elevated; a likely requirement for any future urban system. A substantial reduction in installation costs for a system of this nature can only be achieved by the use of cheap, lightweight and flexible guideways. The British Rail Research maglev vehicle was designed for use on a rigid guideway and it was known that excessive flexibility would make the suspension control system unstable. The aim of the study was to develop a maglev suspension control strategy that was insensitive to guideway flexibility. Vibration measurements were carried out on the Birmingham guideway to establish its modal properties. It was found to be sufficiently rigid to allow the existing controller to work without problems .Measurements were also made on the guideway of a Swiss cablecar transit system. This was felt to represent the extremes of both lightness and flexibility and established the range of guideway dynamics that were likely to be encountered. For the initial experimental work, a section of the British Rail maglev test track was modified to incorporate three sections of flexible track. A personal computer was installed on board the vehicle and software was written to aid frequency response testing and dynamic system modelling. Tests were carried out to establish the dynamic parameters of the new sections of guideway. The existing rigid guideway controller separated magnet control from suspension control. Guideway flexibility destroys this separation and induces additional feedback terms that degrade system stability. Theoretical studies of an improved controller took advantage of the fact that that the suspension magnets act directly onto the guideway and affect the position of both vehicle and guideway. As the guideway is lightly damped it is only flexible over a narrow bandwidth and the new suspension controller is able to use vehicle inertia to react forces that control the guideway at its natural frequency. Theory suggested that this would restore the separation of magnet and suspension control even with a flexible guideway. For a variety of reasons, experimental implementation of the new controller proved to be difficult. Suspension performance on the flexible portions of the guideway was never adequately demonstrated. The work did however enable a very accurate theoretical model of the system to be developed. This model contrasted with earlier predictions because, on rigid guideways, it predicted substantially smaller phase margins than the earlier models had suggested. It showed that the new controller had only modest benefits relative to the original rigid guideway suspension controller. This led to the development of an improved controller, a "lumped" controller where magnet and suspension control are not separated. Modelling for a single degree of freedom vehicle on a single mode guideway showed that large improvements in suspension performance could be made. Further modelling of a three degree of freedom vehicle and a five mode three degree of freedom flexible guideway used parameters that represent the production vehicles at Birmingham. This work defined limits for guideway flexibility and vehicle dynamic performance and showed that maglev guideways for production scale vehicles, with the "lumped" controller, can be very flexible indeed. The major aim of the project was achieved. A suspension controller was developed that will allow a maglev vehicle to work on a guideway that is far lighter, more flexible and far cheaper than the guideway required for a conventional wheeled vehicle.

Since it is difficult to conduct railway ballast testing in-situ, it is important to simulate the conditions experienced in the real track environment and study their influences on ballast in a controlled experimental manner. In this research, extensive laboratory tests were performed on three types of ballast, namely granites A and B and limestone. The grading of the tested ballast conforms to the grading specification in The Railway Specification RT/CE/S/006 Issue 3 (2000). The major laboratory tests in this research were used to simulate the traffic loading and tamping maintenance undertaken by the newly developed Railway Test Facility (RTF) and large-scale triaxial test facility. The Railway Test Facility is a railway research facility that is housed in a 2.1 m (width) x 4.1 m (length) x 1.9 m (depth) concrete pit and comprises subgrade material, ballast, and three sleepers. The sleepers are loaded with out of phase sinusoidal loading to simulate traffic loading. The ballast in the facility can also be tamped by a tamping bank which is a modified real Plasser tamping machine. Ballast breakage in the RTF was quantified by placing columns of painted ballast beneath a pair of the tamping tines, in the location where the other pair of tamping tines squeeze, and under the rail seating. The painted ballast was collected by hand and sieved after each test. It was found from the RTF tests that the amount of breakage generated from the tests was not comparable to the fouling in the real track environment. This is because the external input (such as wagon spillage and airborne dirt) which is the major source of fouling material was not included in the tests. Furthermore, plunging of the tamping tines caused more damage to the ballast than squeezing. The tested ballast was also subjected to Los Angeles Abrasion (LAA) and Micro-Deval Attrition (MDA) tests. It was found that the LAA and MDA values correlated well with the ballast damage from tamping and could indicate the durability of ballast. The large-scale triaxial test machine was specially manufactured for testing a cylindrical ballast sample with 300-mm diameter and 450-mm height and can perform both cyclic and monotonic tests with constant confining stress. Instead of using on-sample instrumentations to measure the radial movement of the sample, it measures sample volume change by measuring a head difference between the level of water that surrounds the sample and a fixed reference water level with a differential pressure transducer. The test results from cyclic tests were related to the simulated traffic loading test in the RTF by an elastic computer model. Even with some deficiencies, the model could relate the stress condition in the RTF to cyclic triaxial test with different confining stresses and q/p' stress ratios.

The most important areas of interest concerning air cored linear machines (ACLM), their design, development and application to guided ground transportation are presented. A description of the origins of high speed guided ground transportation (HSGGT) is given which covers tracked air cushion vehicle and linear induction motor development, as well as the electromagnetic and electrodynamic systems of levitation. ACLM began as the favoured propulsion option for the electrodynamic system, and the machine characteristics of the linear synchronous motor (LSM) are discussed with optimization techniques given for choice of wavelength. Stress factors for rectangular coils with tight corner radii can be calculated using a circular coil equivalent. The linear commutator motor (LCM) provides a means of achieving high local track power density without degrading overall machine performance. Several forms are examined and the trade off and comparison with LSM made. The system comparison of the electrodynamic and electromagnetic systems (EDS and EMS) of magnetic levitation indicates that specifying Just lift to drag ratio and specific energy Intensity is an insufficient base. Comparison is made of the German EMS and EDS designs, together with a comparison of other groups' EDS vehicles. The German EDS design is found to be heavily penalised by excessive low speed suspension weight. Several variations of a new type of ACLM using on board flux pumping are proposed. The advantages are that a passive track structure is possible, and a cryogenically cooled winding can be used as a cost effective alternative to a superconducting coll. Application of ACLM to propulsion of advanced duorail vehicles is set out together with the possibility of speed extension with reduced track wear and Initial capital coat, as well as reduced manning and maintenance cost. An Advanced Passenger Train with LSM would appear to be a feasible option for future transport needs, and extension to a low speed urban vehicle using for example liquid nitrogen cooled pool boiling coils would similarly present a low cost system. An indexed bibliography containing over 400 HSGGT references is included, with a bias to EDS and ACLM.

No description available.

Ground vibration from trains is an increasingly important environmental problem. This study investigates the various excitation mechanisms of ground vibration. An existing semi-analytical model, TGV, which considers both the quasi-static excitation due to moving axle loads and the dynamic excitation due to vertical rail irregularities, has been validated by an extensive measurement campaign. This involved the determination of soil properties at two sites with soft clay soil. These were found to exhibit an inversion of the wave speed profile. Good agreement was found between measurements and predictions of vibration due to train pass-bys. The relative importance of the dynamic and quasi-static excitation mechanisms has been investigated for a range of conditions including changes to track and vehicle parameters. The dynamic excitation mechanism is found to dominate the results above about 10 Hz and at all frequencies for distances beyond 10 m from the track. In order to study other excitation mechanisms a new hybrid model has been developed. This combines a wheel/track interaction model working in the time-spatial domain and an axisymmetric layered ground model working in the wave number-frequency domain. In the time domain model a ‘circular’ track is introduced to allow longer responses to be calculated. The model is then validated by comparison with the existing TGV model. A reasonable agreement is found. The hybrid model has then been used to investigate the relative importance of quasi-static loads, dynamic loads and some other excitation mechanisms for trains running on the ground. The sleeper-passing effect is investigated for both constant and variable sleeper spacing but it is found to give much lower responses than those due to roughness. Variable ballast stiffness is also investigated and found not to be significant. Impact forces caused by the passage of wheels over dipped welds and stepped joints are found to generate ground responses that are considerably larger than roughness excitation in the region close to these track defects. However the response decays more rapidly with distance than that due to roughness.

The aim of this research is to develop a fuller understanding of the mechanical behaviour of the sleeper/ballast interface, related in particular, to the forces applied by high speed tilting trains on low radius curves. The research has used literature review, field measurements, and laboratory experiments on a single sleeper bay of track. Theoretical calculations are also presented. Field measurements are carried out using geophones to record time/deflection for sleepers during passage of Pendolino trains on the West Coast Main Line. Calculations are presented to quantify normal and extreme magnitudes of vertical, horizontal and moment (VHM) loads on individual sleepers. Results from laboratory experiments, on the pre-failure behaviour of the sleeper to ballast base contact area, show that lateral load/deflection behaviour is load path dependent and relations are determined for improved computer modelling of the sleeper/ballast interface. Further test results are used to establish the failure envelopes for combined VHM loading of the sleeper/ballast base contact area. Tests show that the sleeper/ballast base resistance at failure occurs at a load ratio (H/V) of about 0.45 (24°) at 2 mm of displacement tending to 0.57 (30°) at greater displacements. In addition, measurements from pressure plates within the testing apparatus are used to describe the development of confining stress within the ballast during 100 cycles of vertical load. The development of confining stress is assessed with reference to a finite element model of the laboratory apparatus and it is shown that the earth pressure ratio moves towards the active condition for peak load and the passive condition at minimum load per cycle. The contribution to lateral resistance of the crib ballast and varying sizes of shoulder ballast is also established and it is found that the shoulder and crib resistance can best be characterised by taking the mean resistance over a range of deflection from 2 mm to 20 mm. Calculations are presented, supported by the experimental data, to quantify the resistance from different sizes of shoulder ballast and a chart is presented which can be used as the basis for shoulder specification in practice.

For application in damping treatments, elastomeric materials should have a high damping loss factor, but this is inevitably linked to a strong temperature-dependence of the dynamic properties. A methodology is developed that allows a material to be formulated for a particular damping application where temperature-dependence has to be taken into account. The methodology is applied to the case of a tuned absorber system used for damping the vibration of a railway track. This is required to be effective over a temperature range -20°C to 40°C. To investigate the effect of the temperature on the performance of a rail damper, a simple Timoshenko beam model of the track vibration is used, to which are added single-frequency and dual-frequency tuned absorbers. The results show that a high noise reduction can be achieved for the optimum stiffness, provided that the loss factor is between about 0.25 and 0.4. In order to study the generic effects of high damping versus constant stiffness, the time-temperature superposition principle is used to convert frequency-dependence to temperature-dependence for a notional material with constant loss factor. This is used in the prediction of decay rates and thereby noise reduction. In addition, a weighted noise reduction is studied by using measured rail temperature distributions. This temperatureweighted noise reduction allows a single number measure of performance to be obtained which can be used to assess various elastomeric materials in order to determine the optimum material for a given situation. Two types of viscoelastic material, butyl and EPDM rubbers with various amount of fillers and plasticisers are investigated. The properties of both rubbers have been measured over the range of temperatures for frequencies 300-3000 Hz. For this a test rig had to be modified. For butyl, the best combination of filler and plasticiser gives temperature weighted noise reductions up to 5.9 dB(A). Butyl rubber is suitable for use in the rail absorber giving high noise reductions between 0°C and 40°C. The best EPDM compound gives a temperature-weighted noise reduction up to 6.2 dB(A). Comparing these two rubbers, EPDM is more suitable for low temperatures below 10°C and butyl is more suitable for higher temperatures above 10°C.

A model of the development of rail-head acoustic roughness on tangent track has been formulated. The model consists of a two-dimensional time domain wheel-rail interaction force calculation, with the normal force used as the input to a two-dimensional rolling contact and wear model. The possibility of multiple wear mechanisms arising from stress concentrations is considered by using a wear coefficient that can vary with the conditions at each point in the contact. The contact model is based on a variational technique, taking account of non-Hertzian and transient effects. A novel feature of the rolling contact model is the introduction of a velocity-dependent friction coefficient. In rolling contact this leads to a high frequency stick-slip oscillation in the slip zone at the trailing edge. Roughness development depends on the dynamics of the track. Roughness growth has often been linked to the pinned-pinned frequency and other resonances of the coupled track and vehicle system. Here the effect of different vehicle and track parameters on track dynamics, wear and roughness development has been examined. Rail dampers are studied as they change the dynamic response of the track. Results are presented in the form of roughness growth rate functions both for individual vehicle types and for mixed traffic. The model parameters match those at a site used for measurements of roughness development taken by Deutsche Bahn AG as part of the EU project Silence. The study shows that it is important to include non-Hertzian effects when studying roughness with wavelengths shorter than 100 mm. With a non-Hertzian contact model, no mechanism has been found for consistently increasing roughness levels. The model predicts that roughness wavelengths shorter than the contact length will wear away. Rail dampers are shown to reduce the pinned-pinned frequency and smooth the peaks and troughs in the track receptance. Rail dampers also reduce the dynamic wheel-rail interaction forces, especially around the pinned-pinned resonance, and shift the force spectrum to lower frequencies or longer wavelengths. However, rail dampers are not predicted to affect roughness growth rates significantly.