Noise and vibration are generated by forces at the wheel/rail interface. When a train runs through a switch or crossing increased noise and vibration occurs, principally due to impact loading at the crossing nose. This can be a source of considerable annoyance to lineside residents. Other sources of increased noise and vibration include uneven support stiffness and varying dynamic properties of the track through the switch.
Computer models exist of the dynamics of vehicles running through switches and crossings but these require extending to higher frequencies to account correctly for the noise generating mechanisms. The results from these models will then be used together with acoustic models to determine the noise generation and with advanced models of vibration to determine the vibration transmitted through the ground. The linkage between these models requires care to determine the best parameters to use for the interface between them, for example using wheel/rail forces is known to be susceptible to error if the models contain differing degrees of detail. Equivalent displacement inputs can then be used, whereas for ground vibration using the forces beneath the sleepers may be a more robust approach. The project will consider the effects of changes in switch geometry on the noise and vibration generated in different situations. The opportunity exists for experimental work to support the research.
The ’Noise and vibration mitigation at Switches & Crossings’ research project is part TRACK TO THE FUTURE (T2F) a major five-year, £8M research programme, funded by EPSRC, industry and the Universities of Southampton, Birmingham, Huddersfield and Nottingham. Its aim and vision is to support the development of railway track systems that are efficient in terms of embodied carbon, materials use and cost; robust in requiring little maintenance; and unintrusive in producing little noise. It will address this aim through three interlinked Research Challenges RC.
TRACK4LIFE (RC1): low-maintenance, long-life track systems with optimised material use, through
• developing, and demonstrating the effectiveness of, new track forms or components and promising interventions e.g. under-sleeper pads and random fibre ballast reinforcement (1A)
• developing an understanding of the relationships between the key measurable parameters of track stiffness and track settlement, and the key performance parameter of geometrical standard deviation, taking into account the interactions with rail geometry and vehicle dynamics (1B), and
• extending the life of ballast by reducing or eliminating the factors leading to its degradation, assessing the feasibility of design for the degraded state and facilitating re-use rather than downcycling or disposal (1C).
DESIGNER CROSSINGS AND TRANSITIONS (RC2): crossings and transitions that optimise the behaviour of the vehicles traversing them, thereby minimising damage. This will be achieved by developing new understandings of the highly complex interactions between switch and crossing geometry, sub-base support, wheel profile and vehicle dynamics, including the effects of varying the support stiffness through the crossing or transition; and combining them with the potential of modern manufacturing methods to provide a tuned variation in geometry and materials properties.
NOISE-LESS TRACK (RC3): an integrated approach to designing a low-noise, low-vibration track consistent with reduced whole life costs and maintenance needs. Track is the main source of railway rolling noise and has a key role in vibration transmission into the ground. Noise is increasingly cited as the main objection to the expansion, reopening or construction of railways. However, design changes are usually driven by other concerns with the implications for noise and vibration considered as secondary effects.
Applications for this PhD research project are accepted on a rolling basis and we therefore advise you to apply early if you are interested. To make your application please go to: http://www.southampton.ac.uk/engineering/postgraduate/research_degrees/apply.page
If you wish to discuss any details of the project informally, please contact Professor David Thompson, Dynamics research group, Email: [email protected]
, Tel: +44 (0) 2380 59 2510.
This project is being run in participation with the EPSRC Centre for Doctoral Training in Sustainable Infrastructure Systems (http://www.cdt-sis.soton.ac.uk/). For details of our 4 Year PhD programme and further projects, please see http://www.findaphd.com/search/PhdDetails.aspx?CAID=2477
Visit our Postgraduate Research Opportunities Afternoon to find out more about Postgraduate Research study within the Faculty of Engineering and the Environment: http://www.southampton.ac.uk/engineering/news/events/2016/02/03-discover-your-future.page