Hunting is a very common instability exhibited by rail vehicles operating at high speeds. The hunting phenomenon is a self excited lateral oscillation that is produced by the forward speed of the vehicle and the wheel-rail interactive forces that result from the conicity of the wheel-rail contours and the friction-creep characteristics of the wheel-rail contact geometry. Hunting can lead to severe ride discomfort and eventual physical damage to wheels and rails. A comprehensive study of the lateral stability of a single wheelset, a single truck, and the complete rail vehicle has been performed. This study investigates bifurcation phenomenon and limit cycles in rail vehicle dynamics. Sensitivity of the critical hunting velocity to various primary and secondary stiffness and damping parameters has been examined. This research assumes the rail vehicle to be moving on a smooth, level, and tangential track, and all parts of the rail vehicle to be rigid. Sources of nonlinearities in the rail vehicle model are the nonlinear wheel-rail profile, the friction-creep characteristics of the wheel-rail contact geometry, and the nonlinear vehicle suspension characteristics. This work takes both single-point and two-point wheel-rail contact conditions into account. The results of the lateral stability study indicate that the critical velocity of the rail vehicle is most sensitive to the primary longitudinal stiffness. A method has been developed to eliminate hunting behavior in rail vehicles by increasing the critical velocity of hunting beyond the operational speed range. This method involves the semi-active control of the primary longitudinal stiffness using the wheelset yaw displacement. This approach is seen to considerably increase the critical hunting velocity. / Master of Science

The examination of the application and accuracy of optical sensors for the purpose of determining rail lubricity of top-of-rail friction modifier is investigated in this research. A literature review of optical sensors as they relate to detecting thin layers is presented, as well as a literature review of the significant aspect of surface roughness on optical signature. Both commercially available optical sensors and optical devices, such as independent lasers and detectors, are examined in a comprehensive parametric study to determine the most suitable configuration for a prototype with adequate third-body detection. A prototype is constructed considering parameters such as sunlight contamination, vibrations, and angle of detection. The prototype is evaluated in a series of laboratory tests with known lubricity conditions for its accuracy of measurements and susceptibility to environmental conditions, in preparation for field testing. Upon field testing the prototype, the data indicates that it is capable of providing subjective measurements that can help with determining whether a rail is highly lubricated or unlubricated, or it is moderately lubricated. It is anticipated that the device could be used to provide a rail lubricity index. The investigation of the optical response of a rail in various conditions, including top-of-rail friction modifier presence and underlying surface roughness, reveals the behavior of friction modifying material on rail/wheel interactions. It is determined that surface roughness is imperative for distinguishing between scattering due to surface condition and scattering due to third-body layers. Additionally it is revealed that friction modifying materials become entrapped within the surface roughness of the rail, effectively causing a "seasoning" effect instead of a simple third body layer. This provides some explanation on the inadequacy of determining lubricity conditions using contacting methods since they cannot detect the entrapped material that are revealed only when the top of rail undergoes a micro deformation due to a passing wheel. Furthermore, the fluorescent signature of flange grease can be utilized to detect any flange grease contamination on top of rail. The results of the study indicate that it is possible to have practical optical sensors for top-of-rail third body layer detection and any contamination that may exist, initially through spot checking the rail and eventually through in-motion surveying. / Master of Science / Top-of-rail friction modifiers are used in the railway industry for a variety of reasons, including, but not limited to, reduction in wear and fuel savings; although their use has been widely accepted, methods of detection of such materials have not been adequately developed. Presently, methods of measurement of physical aspects of a rail are used in order to deduce the presence or lack of friction modifier on top-of-rail. However, no direct method of measurement exists in the published literature today. This study examines the use of optical sensors for the purpose of determining rail lubricity conditions. The literature is reviewed in this study for all applicable topics pertaining to the optical detection of top-of-rail friction modifier, including the optical theory used and the importance of surface roughness on an optical signature. Different characteristics of optical sensors are examined and a configuration is determined for the construction of a prototype device. This device utilizes laser reflective detectors and a fluorescence sensor in order to distinguish friction modifier presence or other third-body layers. This prototype was tested and evaluated in a series of laboratory tests with known lubricity conditions in preparation for field testing. Additionally, metrics were developed using optical theory in order to quantify the differences between different lubricity conditions. It was seen that this prototype was able to determine the presence of friction modifier by its laser reflective properties, and the presence of flange grease contamination through its fluorescence signature. Field testing with this prototype confirmed the prototype’s ability to distinguish adequate lubricity conditions using these metrics. It is anticipated that the device could be used to provide a rail lubricity index that is able to aid railway professionals in maintenance practices regarding rail lubricity.

Följande studie är gjord på uppdrag av Sjöfartsverket. I studien undersöktes hur en installation av ett Common Rail-system ombord på isbrytaren Ymer påverkat bränsleförbrukningen samt utsläppen av kväveoxider. Rådata som loggats ombord på Ymer har analyserat och bearbetat. Material och information från tillverkare, besättning samt teknisk chef på Sjöfartsverket, Albert Hagander har använts under studien. Tillsammans med uppmätta mätdata och tidigare gjord litteraturstudie stöds resultaten i studien. Det är ingen slump att system av Common Rail-typ redan är tillämpat inom de flesta branscher så som transport, personbilsindustri och jordbruk. Huvudsyftet med Common Rail är att minska bränsleåtgången samt minska utsläppen genom en renare och mer effektiv förbränning av bränslet.  Huvudsakligen undersöktes hur det nyinstallerade systemet påverkat bränsleförbrukningen och hur bränslebesparingen varierar med belastningen av maskinen. Vidare granskades hur utsläppen av kvävedioxider påverkats efter installationen. Problematiken med ökad NOx-produktion till följd av en högre förbränningstemperatur som Common Railsystemet medför diskuteras i rapporten. De resultat vi kommit fram till att en bränslebesparing kan göras ombord på Ymer genom att ersätta det gamla bränslesystemet med ett bränslesystem av Common Rail-typ. Vidare har installationen medfört andra förbättringar så som fartygsmaskinens reaktion på de många lastväxlingar som förekommer under isbrytning. / The following study has been carried out on behalf of Sjöfartsverket. The study examines how the installation of a common rail system on board the icebreaker Ymer affected fuel consumption and emissions of nitrogen oxides. The raw data logged on board Ymer was analyzed and processed. Materials and information from manufacturers, crew and the technical manager at the Swedish Maritime Administration, Albert Hagander have been used during the study. Together with measured data and previously made research study the findings of the study are supported. It is no coincidence that the system of the common rail type is already applied in most industries such as transport, car industry and agriculture. The main purpose of the Common Rail is to reduce fuel consumption and reduce emissions through cleaner and more efficient combustion of the fuel. We primarily examined how the newly installed system affected fuel consumption and the fuel savings will vary with the load of the machine. Furthermore, we examined how emissions of nitrogen oxides were affected after installation. The problem of increased NOx production due to a higher combustion temperature as the common rail system entails are discussed in the report. The result that was concluded was that fuel savings can be made on board Ymer by replacing the old fuel system with a common rail fuel type. Furthermore, the installation has brought other improvements such as ship machine's reaction to the many load changes that occur during icebreaking.

Within the past few decades, commuter rail routes in several major metropolitan areas have been implemented to provide an alternative to automobile transportation. Urban planners in these cities are looking to commuter rail to mitigate congestion and pollution. However, research on the impacts of commuter rail development on the surrounding retail landscape is still needed. In metropolitan Dallas-Fort Worth, the Denton County Transportation Authority recently opened its new A-Train light rail service linking suburban Denton and downtown Dallas. This thesis examines urban changes that occurred in the years before and after the A-Train line's 2011 opening, with a focus on restaurant and retail development in the vicinity of the A-Train stations in Denton County. This analysis evaluates changes in retail density and type, the population surrounding stations, and municipal initiatives that shape the retail landscape of station vicinities. This was done by gathering field data, retailer listings, population data, and conducting interviews with local businesses and city planners. The findings suggest that A-train stations have had a differential impact on the surrounding landscape, depending on the existing retail landscape, the types of retailers present, and the current state of municipal infrastructure that promotes accessibility. Overall, results suggest that urban planners play a vital role in harnessing the potential of commuter rail to promote nearby retail growth.

Afin de comprendre pourquoi tous les nouveaux projets de tramways en cours de développement au Canada sont réalisés en mode partenariat public-privé (PPP) plutôt que grâce au mode traditionnel (gestion publique) utilisé par le passé, cette recherche porte sur trois projets de tramways présentement en cours de réalisation (Edmonton, Ottawa et Toronto). À l’aide de trois études de cas, nous explorons l’argumentaire entourant chacune des décisions menant au choix du mode de gouvernance PPP ainsi que la forme prise par ce PPP. Nous démontrons que dans tous les cas, il est possible d’observer les mécanismes du transfert de politique, tant volontaire que coercitif. Nous croyons que le transfert de politique peut donc fournir un élément de réponse à notre question. De plus, l’argumentaire utilisé par les acteurs locaux pour justifier le choix du mode PPP, bien que semblable sur plusieurs points, comporte tout de même une combinaison de justifications unique à chacun des cas, ce qui nous laisse croire que le PPP est un instrument de politique polyvalent. Ces constats démontrent l’intérêt de prendre en considération les transferts de politique au niveau municipal et non seulement les transferts qui prennent place entre les États nationaux. To understand why all new light rail projects under development in Canada are carried out in public-private partnership (P3) rather than through the traditional mode (public administration) that prevailed in the past, this research explores three light rail projects currently underway in Edmonton, Ottawa and Toronto. We study the arguments surrounding each decision leading to the choice of P3 governance. We show that in all cases, it is possible to observe the mechanisms of policy transfer, whether voluntary or coercive. Moreover, the argument used by local actors to justify the choice of P3, although similar in several respects, still forms a unique combination of justifications for each case, which leads us to believe that P3s are a versatile policy instrument. These findings demonstrate the importance of taking into account policy transfer at the municipal level and not only transfers that take place between national states.

Le secteur des transports ferroviaires en France est marqué par un dynamisme lié notamment à l'essor du réseau à grande vitesse et à la réimplantation du tramway dans de nombreuses agglomérations. Dans ce contexte, la réduction des nuisances sonores apparaît comme un enjeu majeur pour son développement. Afin d'agir efficacement à la source, il est indispensable d'identifier et d'étudier précisément les sources responsables de ces nuisances au passage des véhicules. Parmi les approches possibles, les antennes microphoniques et les traitements associés sont particulièrement adaptés à la caractérisation des sources ponctuelles mobiles, omnidirectionnelles et décorrélées.Pour les vitesses inférieures à 300 km/h, le bruit de roulement constitue la source principale du bruit ferroviaire ; il résulte du rayonnement acoustique des éléments tels que les roues, le rail et les traverses. Le rail, dont la contribution au bruit de roulement est prépondérante aux moyennes fréquences (entre 500 He et 1000 Hz environ), est une source étendue et cohérente pour laquelle les principes classiques de traitement d'antenne ne sont pas adaptés.La méthode de caractérisation proposée dans cette thèse est une méthode inverse d'optimisation paramétrique utilisant les signaux acoustiques issus d'une antenne microphonique. Les paramètres inconnus d'un modèle vibro-acoustique sont estimés par minimisation d'un critère des moindres carrés sur les matrices spectrales mesurée et modélisée au niveau de l'antenne. Dans le modèle vibro-acoustique, le rail est assimilé à un monopôle cylindrique dont la distribution longitudinale d'amplitude est liée à celle des vitesses vibratoires. Pour le calcul de ces vitesses, les différents modèles proposés mettent en évidence des ondes vibratoires se propageant dans le rail de part et d'autre de chaque excitation. Chacune de ces ondes est caractérisée par une amplitude au niveau de l'excitation, un nombre d'onde structural réel et une atténuation. Ces paramètres sont estimés par minimisation du critère, puis utilisés pour reconstruire le champ acoustique.Dans un premier temps, des simulations sont réalisées pour juger des performances de la méthode proposée, dans le cas d'excitations ponctuelles verticales. En particulier, sa robustesse est testée en présence de bruit ou d'incertitudes sur les paramètres supposés connus du modèle. Les effets de l'utilisation de modèles dégradés sont également étudiés. Concernant l'estimation des amplitudes, les résultats ont montré que la méthode est particulièrement robuste et efficace pour les excitations les plus proches de l'antenne. En revanche, pour l'estimation des autres paramètres, les performances sont supérieures pour les positions d'antenne excentrées. De manière générale, le nombre d'onde est correctement estimé sur l'ensemble des fréquences étudiées. Dans les cas à faible atténuation, un traitement classique par formation de voies en ondes planes suffit. En ce qui concerne l'estimation de l'atténuation, la faible sensibilité du critère limite l'efficacité de la méthode proposée.Enfin, certains résultats obtenus à partir des simulations ont été vérifiés lors de mesures in situ. L'excitation d'un rail expérimental par un marteau de chocs a tout d'abord permis de valider le modèle vibratoire pour la flexion verticale. Pour tester la méthode d'optimisation paramétrique, le rail a également été excité verticalement à l'aide d'un pot vibrant. Les principaux résultats des simulations ont été retrouvés, et des comportements particuliers relatifs à la présence de plusieurs ondes dans le rail ont été observés, ouvrant des perspectives de généralisation du modèle vibratoire utilisé. / In France, railway transport has been boosted by the expansion of the high-speed rail service and the resurgent implantation of tram networks in many city centers. In this context, the reduction of noise pollution becomes a crucial issue for its development. In order to directly act on the source area, it is necessary to precisely identify and study the sources responsible for this nuisance at train pass-by. Among all the potential approaches, microphone arrays and related signal processing techniques are particularly adapted to the characterization of omnidirectional and uncorrelated moving point sources. For speeds up to 300 km/h, rolling noise is the main railway noise source. It arises from the acoustic radiation of various elements such as wheels, rail or sleepers. The rail, which mainly contributes to rolling noise at mid-frequencies (from 500 Hz to 1000 Hz approximately), is an extended coherent source for which classical array processing methods are inappropriate. The characterization method proposed in this thesis is an inverse parametric optimization method that uses the acoustical signals measured by a microphone array. The unknown parameters of a vibro-acoustical model are estimated through the minimization of a least square criterion applied to the entries of the measured and modelled spectral matrices. In this vibro-acoustical model, the rail is considered as a cylindrical monopole whose lengthwise amplitude distribution is obtained from the vibratory velocity one. The different models proposed to obtain this velocity highlight the propagation of vibration waves towards both sides of every forcing point. Each wave is characterized by an amplitude at the forcing point, a real structural wavenumber and a decay rate. These parameters are estimated by the minimization of the least square criterion, and are then used in the vibro-acoustical model to rebuild the acoustical field radiated by the rail. First, simulations are performed in order to appraise the performances of the proposed method, in the case of vertical point excitations. In particular, its robustness to additive noise and to uncertainties in the model parameters that are supposed to be known is tested. The effect of using simplified models is also investigated. Results show that the method is efficient and robust for the amplitude estimation of the nearest contacts to the array. On the other hand, the estimation of the other parameters is improved when the array is shifted away from the contact points. The wavenumber is generally well estimated over the entire frequency range, and when the decay rate is low, a single beamforming technique may be sufficient. Concerning the decay rate estimation, the efficiency of the method is limited by the low sensitivity of the criterion. At last, measurements are performed in order to verify some results obtained from the simulations. The vibratory model is first validated for the vertical flexural waves trough the use of an impact hammer. Then, the parametric optimization method is tested by the vertical excitation of the rail with a modal shaker. The main simulation results are found, and some particular behavior due to other waves existing in the rail can be observed, opening the perspective of a generalized method including more complex vibratory modelings.

Depuis plus d'un siècle, l’usure ondulatoire représente un des problèmes de maintenance les plus important pour les réseaux ferroviaires. Celle-ci est à l’origine d’émissions sonores incommodantes pour le voisinage et de vibrations structurelles pouvant réduire la durée de vie des infrastructures et matériels ferroviaires. Ce phénomène périodique présent à la surface des rails est intimement lié à la dynamique du contact roue-rail qui résulte des paramètres régissant le frottement, la dynamique du train et de la voie… Afin de mieux appréhender les conditions menant à l’apparition de l’usure ondulation, un modèle numérique a été proposé pour compenser l’impossibilité d’instrumenter localement et de façon fiable un contact roue-rail dynamiquement. Tout d'abord, un outil approprié a été choisi pour modéliser la dynamique du contact roue-rail afin de reproduire numérique de l’usure ondulatoire des voies rectilignes. Le code d'éléments finis dynamique implicite Abaqus a été choisi pour instrumenter numériquement localement le contact roue-rail. Ainsi, tant l'origine que l'évolution de l’usure ondulatoire dans des phases transitoires (accélération / décélération) sont étudiées. Une étude de sensibilité a été menée pour mettre en évidence la sensibilité de l’usure ondulatoire apparaissant dans des conditions transitoires au passage d’une ou plusieurs roues ainsi que d’un défaut géométrique présent à la surface du rail. Des conditions dynamiques locales d’adhérence-glissement (stick-slip), liées à la dynamique de la roue et du rail couplés par le contact, est identifié comme origine de l’usure ondulatoire des voies rectilignes dans des conditions transitoires. Deuxièmement, les résultats obtenues avec le modèles précédent ont mis en évidence une décroissance de l’amplitude de l’usure ondulatoire reproduire numérique en fonction du nombre de roue passant sur le rail. Ce résultat semble être en contradiction avec les observations de rails réels. Ce problème est lié à la difficulté de gérer la dynamique de contact, et tout particulièrement dans le cas où il y a des impacts locaux, dans les modèles éléments finis classiques tels que ceux implémentés dans Abaqus. Pour palier ce problème, une méthode de masser redistribuée a été implémentée dans Abaqus et utilisée sur le cas précédent. Les résultats montrent un accroissement plus réaliste de l’usure ondulatoire en fonction du nombre de roues. / For more than a century, rail corrugation has been exposed as one of the most serious problems experienced in railway networks. It also comes with a series of problems for maintenance, such as rolling noises and structural vibrations that can reduce lifetime of both train and track. This periodical phenomenon on rail surface is closely linked to wheel-rail contact dynamic, which depends on friction, train dynamics… To better understand corrugation birth conditions, a numerical model is suggested to complement the experimental limitations and to instrument a wheel-rail contact both locally and dynamically. At first, an appropriate tool was chosen to create the dynamic wheel-rail contact model to reproduce straight-track corrugation, also called “short-pitch” corrugation. The implicit dynamic finite element code Abaqus was chosen to investigate the dynamic local contact conditions. Both the origin and the evolution of straight-track corrugation under transient conditions (acceleration / deceleration) are studied. The parametrical sensibility of corrugation is thus investigated both with single/multiple wheel passing(s) and with geometric defect. A stick-slip phenomenon, linked to both wheel and rail dynamics coupled through the contact, is identified as the root of straight-track corrugation under transient conditions. Secondly, results obtained with the previous model have highlighted a quick decrease of corrugation amplitude with the increase of wheel passings over the rail. This last result seems to be in contradiction with reality. This problem comes from the difficulty to reliably manage contact dynamics, and particularly with local impacts, with the use of classical finite element models such as the one implemented in Abaqus. To compensate for this lack, a mass redistribution method is implemented in Abaqus and used with the previous case. The results show a more realistic corrugation growth according to the number of wheel passings.

The diploma thesis deals with construction design and practical realisation of experimental apparatus for investigation of wheel flange track vehicle lubrication. Experimental apparatus in full-scale uses optical interferometry for investigation of lubrication behaviour in wheel flange contact. It is an innovative approach which has not been used for such experiments so far. The aim of the following measurement with this apparatus is to determine the minimal amount of ecological lubrication in wheel flange contact under certain conditions when there is no lubrication film interruption. The apparatus enables to measure real rail wear. This work contains the apparatus description for the study of wheel flange lubrication, wheel flange contact specifications, the description of its influence on wear and acoustic emission, and a detailed description of the experimental apparatus.

Afin de comprendre pourquoi tous les nouveaux projets de tramways en cours de développement au Canada sont réalisés en mode partenariat public-privé (PPP) plutôt que grâce au mode traditionnel (gestion publique) utilisé par le passé, cette recherche porte sur trois projets de tramways présentement en cours de réalisation (Edmonton, Ottawa et Toronto). À l’aide de trois études de cas, nous explorons l’argumentaire entourant chacune des décisions menant au choix du mode de gouvernance PPP ainsi que la forme prise par ce PPP. Nous démontrons que dans tous les cas, il est possible d’observer les mécanismes du transfert de politique, tant volontaire que coercitif. Nous croyons que le transfert de politique peut donc fournir un élément de réponse à notre question. De plus, l’argumentaire utilisé par les acteurs locaux pour justifier le choix du mode PPP, bien que semblable sur plusieurs points, comporte tout de même une combinaison de justifications unique à chacun des cas, ce qui nous laisse croire que le PPP est un instrument de politique polyvalent. Ces constats démontrent l’intérêt de prendre en considération les transferts de politique au niveau municipal et non seulement les transferts qui prennent place entre les États nationaux. To understand why all new light rail projects under development in Canada are carried out in public-private partnership (P3) rather than through the traditional mode (public administration) that prevailed in the past, this research explores three light rail projects currently underway in Edmonton, Ottawa and Toronto. We study the arguments surrounding each decision leading to the choice of P3 governance. We show that in all cases, it is possible to observe the mechanisms of policy transfer, whether voluntary or coercive. Moreover, the argument used by local actors to justify the choice of P3, although similar in several respects, still forms a unique combination of justifications for each case, which leads us to believe that P3s are a versatile policy instrument. These findings demonstrate the importance of taking into account policy transfer at the municipal level and not only transfers that take place between national states.

This Master's Thesis deals with high-speed rail in the Czech Republic. The theoretical part describes the history, the evolution and the present of high-speed rail and presents the successful foreign high-speed rail systems. Furthermore this part presents the high-speed railway tracks which are planned in the Czech Republic. The practical part researches the perception of high-speed rail by passengers. Based on the result of the survey, which was realized via the questionnaire, it analyses the criteria that passengers consider important in the choice of means of transport and it looks into passenger willingness to accept higher fare for shorten of travel time. With using the result of the survey it also deals with competitiveness of high-speed rail compared with other modes of transport. The aim of the Thesis is determine whether high-speed rail is attractive from the perspective of passengers and whether it is able to compete with other modes of transport.