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The tensioning forces applied to the contact wire in a railway catenary system influence the performance of the line. In this paper, a method to monitor the status of such tensioning forces is proposed based on the dependency that the waves that propagate through a tensioned wire have on the forces that pull the wire itself. A novel analytical formulation for the propagation of waves in a tensioned wire was proposed, and it was used to obtain the vertical acceleration of the wire when an external force acts as a concentrated input. The analysis of the acceleration with a moving standard deviation allowed a method to be defined for the generation of an index that describes the trend of the tensioning forces. The method was then tested on the wire accelerations obtained with laboratory tests and, afterwards, on the accelerations recorded on a contact wire of an electric railway regularly in operation and excited with the same kind of input. [ABSTRACT FROM AUTHOR]

The pantograph-catenary interaction is crucial for running trains on electrical railway lines. The coupled dynamic problem of an in space stationary system, the catenary system, and a system in motion, the pantograph, is dependent on the behaviour of both combined as well as individually. Different catenary systems exhibit different behaviour. This paper evaluates a catenary system upgrade by dynamic assessment. Existing railway catenary sections are upgraded or replaced due to wear, but also due to an aim for improved running quality or increased speed on the rail line. Field measurements were conducted on an old catenary section. This section was then upgraded, and some months later measurements were conducted on the new catenary section. Thus, field measurements were sampled at the same location twice. Since the measurements were sampled only months apart and that all measurements are recording behaviour under regular train operation, the loading is assumed to be identical. Dynamic assessment of both sections has been done using power spectral densities and histograms. Important differences and similarities in their response can be seen. This study further increases the knowledge regarding the dynamic behaviour of railway catenary sections when evaluating the impact of the upgrades. [ABSTRACT FROM AUTHOR]

The contact force between the pantograph and the contact wire ensures energy transfer between the two. Too small of a force leads to arching and unstable energy transfer, while too large of a force leads to unnecessary wear on both parts. Thus, obtaining the correct contact force is important for both field measurements and estimates using numerical analysis. The field contact force time series is derived from measurements performed by a self-propelled diagnostic vehicle containing overhead line recording equipment. The measurements are not sampled at the actual contact surface of the interaction but by force transducers beneath the collector strips. Methods exist for obtaining more realistic measurements by adding inertia and aerodynamic effects to the measurements. The variation in predicting the pantograph–catenary interaction contact force is studied in this paper by evaluating the effect of the force sampling location and the effects of signal processing such as filtering. A numerical model validated by field measurements is used to study these effects. First, this paper shows that the numerical model can reproduce a train passage with high accuracy. Second, this study introduces three different options for contact force predictions from numerical simulations. Third, this paper demonstrates that the standard deviation and the maximum and minimum values of the contact force are sensitive to a low-pass filter. For a specific case, an 80 Hz cut-off frequency is compared to a 20 Hz cut-off frequency, as required by EN 50317:2012; the results show an 11% increase in standard deviation, a 36% increase in the maximum value and a 19% decrease in the minimum value. [ABSTRACT FROM PUBLISHER]

An increasing demand for reduced travel times requires the exploitation of the full capacity of existing overhead railway catenary systems. This need has become an issue in Norway, as the majority of existing catenary systems are designed for a maximum speed of 130 km/h. In many regions, plans to reconstruct the railway line do not exist. Therefore, existing catenary sections must be optimized to increase a train’s velocity and reduce the total travel time. In this paper, the dynamic response is evaluated in an optimization investigation of an existing soft catenary system. A dynamic investigation that considers finite element models of existing soft railway catenary sections with original tension forces, current tension forces and suggested new tension forces for velocities at and above the design speed is conducted. The dynamic response is quantified by the interpretation of spectral densities and variations in their peak values. Due to more movement at mid-span than at the pole support, the effects from altering the tension forces and increasing the speed can be more accurately described and estimated by considering the dynamic content of the response at mid-span instead of the peak uplift at the pole support. A 23% increase in speed is possible for the system with the best tested new tension force setting, in which only the dynamic response and uplift at the pole support are considered. [ABSTRACT FROM AUTHOR]

Significant advances made on the rolling stock have considerably increased the possibility of higher speeds in existing railways. Thus, it is important to explore higher speeds and potential limiting factors of existing soft catenary systems. The present paper investigates procedures to assess the dynamic behaviour of these systems using response sampling and modal analysis. The assessment evaluates and quantifies dynamic response along the section. To verify the approach, a case study is conducted and the following assessment methods are used: lengthwise track correlation estimating dynamic predictability, power spectral density estimations before and after passage and short-time Fourier transforms and spectrograms. The combination provides detailed information on the dynamic behaviour. The first part introduces necessary considerations for suggested modal analysis. The second part describes an existing Norwegian section. The case study is conducted using a finite element model including a straight and a given section between Oslo-Trondheim, providing detailed evaluations and system limitation detections. [ABSTRACT FROM AUTHOR]

The design of a railway catenary is subject to multiple decisions regarding the geometry of the system. In particular, the horizontal geometry of the contact wire determines the evolution of the wear of the contact wire and contact strip over time. The horizontal geometry is obtained through the stagger, a lateral displacement of the contact wire at the supports. The value of the stagger, length of the span, curvature of the track, and train speed within the span determine the speed at which the contact point between the wire and the pantograph moves over the contact strip from side to side. A wider stagger corresponds to a larger area of the wear distribution over the contact strip. However, the speed at which the contact point moves over the strip is also important to the wear due to the sliding contact. Thus, the catenary design affects the contact strip wear through the lateral speed of the contact point. In this paper, a study of the lateral speed effects on contact strip wear is presented. The findings include a model of the lateral speed effect on the wear and a recommendation for a lower limit value for the lateral speed of 330 mm/s. • Wear models are needed to overcome uncertainties due to lack of field measurements. • Dependence of wear from speed, force and current has been studied extensively. • The lateral speed of the contact point between pantograph and catenary is known to influence the wear. • The dependence of contact strip wear from the lateral speed is studied. • The wear model is updated to consider the new findings. [ABSTRACT FROM AUTHOR]

• Pantograph-catenary interactions at an existing overlap span are investigated. • A novel optical-based method is proposed and implemented at the overlap span. • Single- and double-pantograph train passages are obtained and studied. • Dynamic effects rendering high contact forces, contact loss and arcing are studied. • Peak contact force, transition distance and train speed show a strong correlation. Smooth pantograph-catenary contact is essential for regular train operation. However, catenary section overlaps are locations where peak contact forces occur, which significantly affects current collection quality. This work studies pantograph-catenary interaction and transition at an existing overlap span by using a novel optical-based measuring method. Image sequences of eleven single- and two double-pantograph train passages were processed to obtain wire displacement responses. The unsynchronised vibration of two contact wires was found, and the first contact wire exhibits different modal responses. The spatial motion paths of contact wires were obtained to estimate the pantograph-catenary interaction. Dynamic effects rendering high contact forces, contact loss and arcing were investigated. The results show that pantographs with a long transition distance and a high intersection gradient cause a serve impulse with the second contact wire, resulting in contact loss and arcing. Finally, this study successfully estimated the transition distance and found it has a strong positive correlation with peak contact forces and train speeds. The transition distance exhibits an increasing tendency with increasing train speed. The longer transition distance results in a higher peak contact force. [ABSTRACT FROM AUTHOR]

• The measurement data is used to validate the pantograph-catenary model in overlap sections. • Strong dependence on interaction performance of the speed with crossing point height is observed. • Steady arm damper improves the trailing pantograph's performance but sacrifice the leading one's. The overlap section is a railway catenary arrangement where the pantograph transfers from one section to another. In the overlap section, the unsynchronised vibration of two contact wires, contact wire height variation, and elasticity unevenness destabilise the pantograph-interaction performance. This paper presents a systematic investigation of the dynamic behaviours of the pantograph-catenary in an overlap section, including the mathematical modeling, model validation and numerical analysis. In combination with the traditional shape-finding method, an initialization procedure is proposed to accurately describe the crossing point height in an overlap section of a catenary. The measurement data of the maximum uplift of the crossing point collected from the field test in the Gardemobanen line is utilised to validate the pantograph-catenary model in the overlap section. The numerical analysis mainly focuses on the effect of the crossing point height and the inclusion of steady arm damping on the interaction performance at different speeds. The results indicate a strong dependence of the dynamic behaviour in an overlap section on the train speed. A good performance can be achieved with a low crossing point when the speed is much lower than the design speed, while a high crossing point can benefit the transition distance and maximum contact force at high speed. The inclusion of a steady arm damper can improve the pantographs' performance at a low speed. However, the effectiveness degrades with the increase of the train speed, especially for the leading pantograph. [ABSTRACT FROM AUTHOR]