Abstract

This paper reviews current track loading requirement (ballasted and ballastless) Typical vehicle-track interaction loads are described along with their influential factors. Limits and influential factors are analysed against statistical evidence from vehicle dynamics measurement. Additional load combinations are presented as potentially relevant for track design. Discussion are made on the potential reduction of load from improved vehicle performance and slab track improved geometry, areas which might bear some benefits in terms of cost reduction for future slab track designs. This paper demonstrates that both vehicle measurement and simulations can provide an important source of information in terms of expected track loading and their limit values to help achieve cost reduction in track design.

Abstract

Railway track support conditions are known to deeply affect the dynamic performance of vehicle-track interaction, influencing the state of the track system both in the short and in the long term. Exactly how much and how is not precisely understood and the notion of track stiffness, although thought to be a key parameter of the track quality, is currently not being monitored systematically. This paper seeks to analyse the influence on the ballast behaviour of track vertical stiffness and especially its spatial non-uniformity, using available experimental data measured at different sites. Mathematical models are developed and the effectiveness of applying under sleeper pads is also investigated. Finally, an iterative procedure based on Guerin’s settlement law is used to take into account the long-term behaviour of the ballast. Such models can help to understand mitigation solutions as well as predicting track quality evolution over time.

Abstract

Impact forces generated in the load transfer area of railway crossing panels lead to a range of degradation modes from wear and fatigue of the contacting materials, fatigue of supporting components to ballast/subgrade deterioration. A simplified modelling approach has been developed to first analyse the geometrical problem of the axle rolling through the crossing geometry, and in a second step to predict the vertical dynamic force produce from the interaction between the wheel unsprung mass and the track system. The force is analysed in the frequency domain to estimate the level of damage in different parts of the track system. A parametric analysis of wheel shapes was carried out showing that the axle lateral displacement has a significant influence on the produced level of damage and also that characteristics such as the wheel flange thickness and the equivalent slope in the area of contact also leads to increased damage. It is suggested that such a measure in combination with the simplified algorithms developed here could be used, possibly in combination with track side monitoring system, to highlight traffic instances leading to increased asset damage.

Abstract

Railway switches and crossings (S&C) are the most costly items for railway infrastructure managers. In the UK over 20% of the planned maintenance and renewal budget for 2014-19 is taken by S&C despite the fact that they only represent a small proportion of the network in terms of km-installation. They are complicated and expensive assets, representing a bottle neck with potential for costly traffic disruptions while attracting a large proportion of the networks failures (e.g. Point Operating Equipment - POE related). Recent European projects (e.g. Innotrack, Sustrail, Drail, Capacity4Rail) and the new H2020/Shift2Rail opportunities for funding are enabling industry and research institutes to work together with infrastructure managers and suppliers to help rethink and redesign a technology which in some aspects remains truly embedded in the middle of last century. What was then a satisfactory design is now being proven beyond its intended design capacity, with ever increasing loads, traffic speed and frequency; while at the same time the window for maintenance and intervention is being drastically narrowed. \\ud One fundamental aspect emerging from these previous research programmes is that a lot of the observed failures surrounding S&C have their root cause explained by the discontinuities experienced by the vehicle at S&C. The nature of these is related to the varying geometrical interface between the vehicle wheels and the guiding rails (e.g. load transfer between stock and switch rails), as well as the uneven vertical support offered to the vehicle through the S&C (e.g. uneven loading of long bearers, increased bending stiffness of cast crossings). A large number of reliability issues find their source in the physical vibrations and dynamically amplified loads occurring because of these two facts, this includes some of the gradual deterioration experienced by POE. Research institutes, including the Institute of Railway Research at the University of Huddersfield, have helped develop advanced simulation tools capable of confidently predicting these phenomena and assess contributory factors to degradation modes as well as iteratively work on remedial actions. These might either be small step changes to existing designs or they might be radical concept changes, covering short, medium and long term vision for 2050 railways in Europe. The author will summarise some of the outcome of recent EU projects, give examples of were simulation technology might be used to assess future improvements and radical changes, as well as opportunities for validating these and other wheel-rail interface research projects using advanced testing techniques.

Abstract

The narrow-gauge locomotive ‘Hydrogen Pioneer’, which was developed and constructed at the University of Birmingham, was employed to establish the performance of a hydrogen-hybrid railway traction vehicle. To achieve this several empirical tests were conducted. The locomotive utilises hydrogen gas in a Proton Exchange Membrane Fuel Cell power-plant to supply electricity to the traction motors or charge the on-board lead-acid batteries. First, the resistance to motion of the vehicle was determined, then operating tests were conducted for the speeds 2 km h−1, 6 km h−1, 7 km h−1, and 10 km h−1 on a 30 m straight, level alignment resembling light running. The power-plant and vehicle efficiency as well as the performance of the hybrid system were recorded. The observed overall duty cycle efficiency of the power-plant was from 28% to 40% and peak-power demand, such as during acceleration, was provided by the battery-pack, while average power during the duty cycle was met by the fuel cell stack, as designed. The tests establish the proof-of-concept for a hydrogen-hybrid railway traction vehicle and the results indicate that the traction system can be applied to full-scale locomotives. Document type: Article

Abstract

Nowadays, sustainability and resilience have become a major consideration that cannot be neglected in urban development. People are starting to consider utilizing the urban infrastructure environment to maintain and improve the functionality and availability of the urban system when unexpected events take place. Traffic congestion is always a major issue in urban planning, especially when the vehicles in the roadway keep growing and the local authorities are lack of solutions to manage or distribute the traffics in the city. It has huge impact on urban sustainability and resilience such as overload of the city’s infrastructure, and air pollution, etc. This paper presents a survey on the challenges of developing sustainable and resilient transportation networks and the current urban traffic optimisation methods, as a possible solution to address such challenges. It aims to describe and define the state of the art on the research on sustainable and resilient transportation networks in urban development and a taxonomy of different traffic optimisation methods used for avoiding traffic congestion and improve urban traffic management.

Abstract

dvanced urban traffic control systems are often based on feed-back algorithms. For instance, current traffic control systems often operate on the basis of adaptive green phases and flexible co-ordination in road (sub) networks based on measured traffic conditions. However, these approaches are still not very efficient during unforeseen situations such as road incidents when changes in traffic are requested in a short time interval. Therefore, we need self-managing systems that can plan and act effectively in order to restore an unexpected road traffic situations into the normal order. A significant step towards this is exploiting Automated Planning techniques which can reason about unforeseen situations in the road network and come up with plans (sequences of actions) achieving a desired traffic situation. In this paper, we introduce the problem of self-management of a road traffic network as a temporal planning problem in order to effectively navigate cars throughout a road network. We demonstrate the feasibility of such a concept and discuss our preliminary evaluation in order to identify strengths and weaknesses of our approach and point to some promising directions of future research.

Abstract

Turnouts are a key element of the railway system. They are also the part of the system with the highest number of degradation modes and associated failures. There are a number of reasons for this, including high dynamic loads resulting from non-uniform rail geometry and track support stiffness. The main aim of this study is to propose a methodology to optimise the pad stiffness along a crossing panel in order to achieve a decrease in the indicators of the most common failure modes. A three-dimensional vehicle/track interaction model has been established, considering a detailed description of the crossing panel support structure. A genetic algorithm has been applied to two main types of constructions, namely direct and indirect fixing, to find the optimum combinations of resilient pad characteristics for various cases of travelling direction, travelling speed and support conditions.