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EPSRC Reference: EP/K03765X/1
Title: TRACK SYSTEMS FOR HIGH SPEED RAILWAYS: GETTING IT RIGHT
Principal Investigator: Powrie, Professor W
Other Investigators:
Thompson, Professor DJ Zervos, Dr A Griffin, Professor M
Hu, Dr Z Priest, Dr JA
Researcher Co-Investigators:
Project Partners:
Arup Group Ltd High Speed Two HS2 Ltd HS1 Ltd (High Speed 1)
URS Infrastructure & Environment UK Ltd
Department: Faculty of Engineering & the Environment
Organisation: University of Southampton
Scheme: Standard Research
Starts: 28 February 2014 Ends: 27 February 2018 Value (£): 830,021
EPSRC Research Topic Classifications:
EPSRC Industrial Sector Classifications:
Transport Systems and Vehicles
Related Grants:
EP/K037676/1
Panel History:
Panel DatePanel NameOutcome
25 Jun 2013 Engineering Prioritisation Meeting 25 June 2013 Announced
Summary on Grant Application Form
Train speeds have steadily increased over time through advances in technology and the proposed second UK high speed railway line (HS2) will likely be designed with "passive provision" for future running at 400 km/hour. This is faster than on any ballasted track railway in the world. It is currently simply not known whether railway track for speeds of potentially 400 km/hour would be better constructed using a traditional ballast bed, a more highly engineered trackform such as a slabtrack or a hybrid between the two. Although slabtrack may have the advantage of greater permanence, ballasted track costs less to construct and if the need for ongoing maintenance can be overcome or reduced, may offer whole-life cost and carbon benefits. Certain knowledge gaps relating to ballasted track have become apparent from operational experience with HS1 and in the outline design of HS2. These concern

1. Track Geometry: experience on HS1 (London to the Channel Tunnel) is that certain sections of track, such as transition zones (between ballasted track and a more highly engineered trackform as used in tunnels and on bridges) and some curves require excessive tamping. This results in accelerated ballast degradation and increased ground vibration; both have an adverse effect on the environmental performance of the railway in terms of material use and impact on the surroundings. Thus the suitability of current design rules in terms of allowable combinations of speed, vertical and horizontal curve radius, and how these affect the need for ongoing maintenance to retain ride quality and passenger comfort is uncertain.

2. Critical velocity: on soft ground, train speeds can approach or exceed the speed of waves in the ground giving rise to resonance type effects and increased deformations. Instances of this phenomenon have been overcome using a number of mitigation measures such as the rebuilding of the embankment using compacted fill and geogrids, installation of a piled raft and ground treatment using either deep dry soil mixing or controlled modulus columns. The cost of such remedial measures can be very high, especially if they are taken primarily on a precautionary basis. However, many methods of analysis are unrefined (for example, linear elastic behaviour is often assumed or the heterogeneity of the ground, track support system and train dynamics are neglected), and conventional empirical methods may significantly overestimate dynamic amplification effects. Thus there is scope for achieving considerable economic benefits through the specification of more cost effective solutions, if the fundamental science can be better understood.

3. Ballast flight, ie the potential for ballast particles to become airborne during the passage of a very high speed train. This can cause extensive damage to the undersides of trains, and to the rails themselves if a small particle of ballast comes to rest on the rail and is then crushed. Investigations have shown that ballast flight depends on a combination of both mechanical and aerodynamic forces, and is therefore related to both train operating conditions and track layouts, but the exact conditions that give rise to it are not fully understood.

The research idea is that, by understanding the underlying science associated with high speed railways and implementing it through appropriate, reasoned advances in engineering design, we can vastly improve on the effectiveness and reduce maintenance needs of ballasted railway track for line speeds up to at least 400 km/h.
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Organisation Website: http://www.soton.ac.uk