There is increasing interest in the potential of urban rail to reduce the impact of metropolitan transportation due to its high capacity, reliability and absence of local emissions. However, in a context characterised by increasing capacity demands and rising energy costs, and where other transport modes are considerably improving their environmental performance, urban rail must minimise its energy use without affecting its service quality. Urban rail energy consumption is defined by a wide range of interdependent factors; therefore, a system wide perspective is required, rather than focusing on energy savings at subsystem level. This paper contributes to the current literature by proposing an holistic approach to reduce the overall energy consumption of urban rail. Firstly, a general description of this transport mode is given, which includes an assessment of its typical energy breakdown. Secondly, a comprehensive appraisal of the main practices, strategies and technologies currently available to minimise its energy use is provided. These comprise: regenerative braking, energy-efficient driving, traction losses reduction, comfort functions optimisation, energy metering, smart power management and renewable energy micro-generation. Finally, a clear, logical methodology is described to optimally define and implement energy saving schemes in urban rail systems. This includes general guidelines for a qualitative assessment and comparison of measures alongside a discussion on the principal interdependences between them. As a hypothetical example of application, the paper concludes that the energy consumption in existing urban rail systems could be reduced by approximately 25-35% through the implementation of energy-optimised timetables, energy-efficient driving strategies, improved control of comfort functions in vehicles and wayside energy storage devices.

Increasing the acceleration and deceleration of trains within a railway network can improve the performance of the system. However, the risk of passengers losing their balance and falling is also increased. The purpose of this paper is therefore to examine the effect of longitudinal vehicle accelerations on passenger safety and comfort. The literature review brings together two separate disciplinary areas, considering the effects of acceleration on balance from a physiological/kinesiological perspective, as well as looking at the results of previous empirical studies on the levels of acceleration that railway passengers will tolerate. The paper also describes an experiment carried out on the Tyne and Wear Metro, which gathered data on typical acceleration levels to compare against the findings of the literature review. It was found that both the magnitude of the accelerations and their rate of change (jerk) are important. The results also suggest that there may be scope to improve the trade-off between journey times, energy consumption and passenger comfort by fine control of the acceleration/jerk profile. This is particularly relevant to urban rail systems, as they typically feature relatively high acceleration and deceleration. However, the findings for passenger comfort are equally applicable to conventional regional and intercity services.

This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License ePrints -Newcastle University ePrints http://eprint.ncl.ac.uk Experimental assessment of the energy consumption of urban rail vehicles during stabling hours: influence of ambient temperature

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Metro systems around the world have many differences in their design and operation, one aspect of which is the level of automation. The most advanced technology available allows for unattended train operation with no staff on-board, which can bring a number of benefits. As a result, this is becoming increasingly common for new-build metro systems (such as the Dubai Metro), as well as for upgrades of traditional driver-led systems (such as Paris Métro Line 1). This paper uses the Tyne and Wear Metro as a case study to highlight the potential benefits and obstacles of implementing driverless trains on an existing metro system. This investigation has two parts: a review of the challenges of implementing increasing levels of automation for the existing Metro infrastructure and a simulation exercise to compare automatic train operation with manual driving on the core section of the Metro network. The results of the simulation exercise show that significant increases in the capacity of the Tyne and Wear Metro system are possible when automatic train operation is implemented in conjunction with resignalling. However, low adhesion conditions represent a significant risk to achieving this capacity increase reliably, and additional measures to mitigate low adhesion conditions would be required. The study also discusses the infrastructure upgrades required to convert an existing system to unattended train operation. The most significant obstacle for the Metro is that it mostly runs at ground level, with some sections shared with main line services. The costs associated with securing the tracks and ensuring compatibility with main line trains mean that the Metro is not a particularly promising application for driverless train operation at this time. Nonetheless, the issues discussed in the paper are very much relevant for other metro systems, and the methodology of this study is easily transferrable.