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.
- Track Geometry: to investigate 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, given that excessive maintenance required on some sections of existing high-speed track.
- Critical velocity: through the improved fundamental scientific understanding of the phenomenon, to refine the methods of analysis of ground waves and resonance type effects excited by high speed trains on soft ground, leading to economic benefits through the specification of more cost-effective solutions.
- Ballast flight, ie the potential for ballast particles to become airborne during the passage of a very high-speed train. To understand the exact conditions that give rise to ballast flight, which 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.
- Take field measurements of track system performance during train passage at problem sites before and after maintenance interventions, leading to analysis and recommendations.
- Develop three sets of numerical and analytical models of selected well- and poorly-performing sites (a) to understand the parameters affecting deterioration; (b) to analyse critical velocity effects and the effectiveness of proposed mitigation models; and (c) develop models of track-to-passenger-perception.
- Study of ballast flight by computerised fluid dynamics modelling, validated by laboratory tests.