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.

No description available.

Thesis (C.E.)--Lehigh University, 1877. / Caption title. Also available online.

Thesis (doctoral)--Ludwig-Maximilians-Universität München.

Thesis (doctoral)--Universität Köln.

Thesis (doctoral)--Universität Köln, 1939. / "Erweiterter Sonderdruck aus 'Archiv für Eisenbahnwesen' 1940, Heft l."

Thesis (doctoral)--Universität Breslau, 1914. / Includes bibliographical references ([v]-vii).

Thesis (Ph. D.)--University of Wisconsin, 1899. / Bibliography: p. 127-130.