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The long-term preservation of our infrastructure requires not only intelligent sensor technology and highly developed monitoring procedures, but also innovative digital tools for analyzing, evaluating and utilizing the results. This includes mathematical and, in particular, probabilistic methods for damage detection and tracking as well as for calculating service life and maintenance cycles and data management. The example project Maintal Bridge Gemuenden as part of the AISTEC project shows the workflow for the implementation of structural health monitoring and experimental tests with a train of Deutsche Bahn. The influence lines, as one possible way for damage detection, were measured with a highly accurate GNSS System to locate the trains position when crossing the bridge. The results were compared to measurements from 1987 just before the bridge went in operation.
The passage of the train is dominated by the impulses of the static axle loads. The response of the regular homogeneous and irregular soils has been calculated by the finite-element method in frequency domain. The superposition of the impulse responses yields the quasi-static component of the ground vibration which is restricted to very low frequencies and to the close near-field of the track. In case of an irregular soil or ballast of which the stiffness varies randomly in space, a mid-frequency ground vibration component is generated by the scattering of the axle impulses. Measurements will be shown which prove the existence of the mid-frequency ground vibration component and the unique explanation by the scattered axle impulses: many international measurements with a raised mid-frequency component, axle-box measurements with a too low mid-frequency dynamic load, amplitude-speed dependencies which are incompatible with irregularity-induced dynamic loads, and ground vibration reductions due to stiff track elements.
The passage of the train is dominated by the impulses of the static axle loads. The response of the regular homogeneous and irregular soils has been calculated by the finite-element method in frequency domain. The superposition of the impulse responses yields the quasi-static component of the ground vibration which is restricted to very low frequencies and to the close near-field of the track. In case of an irregular soil or ballast of which the stiffness varies randomly in space, a mid-frequency ground vibration component is generated by the scattering of the axle impulses. Measurements will be shown which prove the existence of the mid-frequency ground vibration component and the unique explanation by the scattered axle impulses: many international measurements with a raised mid-frequency component, axle-box measurements with a too low mid-frequency dynamic load, amplitude-speed dependencies which are incompatible with irregularity-induced dynamic loads, and ground vibration reductions due to stiff track elements.
Non-destructive testing (NDT) is a major contributor to the safe railway operation. Even though NDT reliability in railway maintenance is affected by human factors, there are only just a few studies published in this field so far. Education and training of the NDT personnel are some of the most important drivers of safe and reliable NDT. Continuously improving current practices and tools used for educational purposes can be achieved not only through technical con¬tent, but also through the attention to human factors. The aim of this study was to deepen the understanding of possible human-related risks in the manual ultrasonic inspection of the hollow railway axles and to suggest measures to improve the education and training of the NDT person¬nel. This was achieved by means of Failure Modes and Effects Analysis (FMEA) carried out with eight NDT experts and by a survey of 27 experienced inspectors. The results show that failures can happen throughout the entire NDT process. Prevention of those failures could be improved through the optimization of the organization, technology, documentation and regulations, working conditions and the general process, and through the optimization of the formal education and training. Specialized training of the executives, extended training of the supervisors and the inspectors and improvement of the inspection documentation have been suggested. The study also showed potential for the improvements of the inspection in the field.
Non-destructive testing (NDT) is a major contributor to the safe railway operation. Even though NDT reliability in railway maintenance is affected by human factors, there are only just a few studies published in this field so far. Education and training of the NDT personnel are some of the most important drivers of safe and reliable NDT. Continuously improving current practices and tools used for educational purposes can be achieved not only through technical content, but also through the attention to human factors. The aim of this study was to deepen the understanding of possible human-related risks in the manual ultrasonic inspection of the hollow railway axles and to suggest measures to improve the education and training of the NDT personnel. This was achieved by means of Failure Modes and Effects Analysis (FMEA) carried out with eight NDT experts and by a survey of 27 experienced inspectors. The results show that failures can happen throughout the entire NDT process. Prevention of those failures could be improved through the optimization of the organization, technology, documentation and regulations, working conditions and the general process, and through the optimization of the formal education and training. Specialized training of the executives, extended training of the supervisors and the inspectors and improvement of the inspection documentation have been suggested. The study also showed potential for the improvements of the inspection in the field.
The efficiency and safety of railway transportation depends on many factors and operating conditions, associated to the vehicle, the infrastructure, the operator and the environment. From the vehicle-infrastracture perspective, some influential factors include the dynamics of the vehicle and infrastructure interaction when the vehicle operates on curved tracks. Düring such changes of direction, the vehicle dynamically responds to the lateral perturbation, producing a lateral load transfer that represents an increase of the wheel forces on one side of the track, as a function of the train operating conditions and track design, including track's geometry and over-elevation, and vehicle's operating speed as well as its inertial properties and dimensions. In this context, the lateral load transfer superimposes to tangential steering forces, which are developed when the vehicle enters the curved track, and stabilize once a steady state is attained if the vehicle travels along a constant radius track at constant speed. The magnitude of such tangential forces depends on a variety of factors, including the yaw stiffness of the bogie, and the friction at the centre plate. While the friction at the
centre plate generates higher tangential forces on the track and a consequential greater rail wearing and lose of locomotive energy, such friction is also crucial to avoid the hunting phenomenon when the vehicle travels along tangents.
In this paper, a mechanically active centre plate is proposed, which increases the friction torque at the centre plate when the vehicle travels along tangents, and reduces such a friction torque when the vehicle negotiates curved portions of the track. Such conceptual design includes the principles of Operation and a needed preliminary
experimental model to assess the potential benefits as well as the feasibility of such equipment.
An experimental testing rig has been proposed to study the dynamic interaction between a liquid cargo and the carrying vehicle during turning maneuvers. The basic operational principle of the testing rig consists in simulating the lateral accelerations associated to turning maneuvers through the use of a tilt table.
While the experimental capabilities of the testing rig include the analysis of the effects of the cars on the whole transport infrastructure, including sleepers and ballast, a first use of the rig considered the effect of sloshing cargo on the level of dynamic forces transmitted to the rails. Such test was used to validate a simplified theoretical approach consisting of a two degree-of-freedom double pendulum mechanical system, where a simple pendulum, representing the sloshing cargo, is articulated to the spring-supported vehicle chassis, which is modelled as an inverted torsional pendulum. While the theoretical results exhibit a high correlation with the experimental data, the main discrepancy between both outputs, relates with the frequency of the residual vibration, once the lateral acceleration input is ceased. Such difference in frequency, would imply an underestimation of the number of loading cycles to which the infrastructure is subjected. On the other hand, the peak values are within acceptable difference levels.
Effective assessment and management of railway infrastructure for competitiveness and sustainability
(2018)
In this chapter the challenges facing railways have been illustrated through the description of two important events occurring in different geographical areas. While the explosion in Quebec, Canada, points out the importance of taking away the transportation infrastructure from highly populated areas; the disruption of the European railway network in Rastatt, Germany, describes the importance of designing alternative routes to critical railway segments, together with the need to have contingency plans to face extraordinary situations regarding the connectivity in a given transport network.
Future research efforts are recognized in relation with the railway car – track interaction, as the dynamic loads derived from such interaction could be reducing the life of such infrastructure. It is particularly important for infrastructures dedicated to the transportation of liquid hazardous substances.