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.

Cities compete with each other. For more than fifty years, Public Choice Theory has explored the notion that cities compete to attract and retain residents and businesses. Likewise, the Public Finance & Tax Competition literature identifies competition between cities on tax-and-spend policies. The evidence base suggests 'inter-city competition increases the likelihood cities will pursue a limited strategy versus a balanced or more progressive approach'. In the transport sector, fiscal demand management policies such as road user charging, workplace parking levies and parking charges are therefore issues upon which cities may compete. Both residents and businesses are deeply concerned about the implications of changes to charging regimes. The negative impacts they foresee may in turn influence not only transport decisions, but also (in the long run) location decisions. Thus, there are indirect impacts on the local economy, which provides a stimulus for inter-city competition. Buchan (2008), reviewing policies to combat climate change impacts from transport, concluded that a nationally-imposed parking charge on new developments was necessary, in order 'to avoid local authority fears of destructive competition from neighbouring authorities'. Fiscal management of transport demand is therefore a clear potential source of competition between cities, yet there is little research to guide us on how strong this competition might be, how much of the competitive pressure is real or perceived, and how it should affect the design, implementation and overall effectiveness of fiscal demand management policies. Our research will study the issues surrounding the design and implementation of parking and charging policies looking more specifically at competing cities with the aim to answer the following policy questions :- In what ways do and could cities compete using fiscal demand management policies? How should cities design their policies to achieve individual and collective 'best' outcomes? Should cities consider sharing revenue streams - should they compete or co-operate? How significant are these policies to the redistribution of business and residents between cities? What, if any, implications do the results have for the co-ordination of demand management policies?The research will be based on a mix of in-depth interviews with selected cities and mathematical models of competition between cities covering both short term and long term dynamics and behaviour of relevant stakeholders.

Infrastructure systems such as water, transport and energy are vital to British society and the economy. It is very important that these systems are able to continue to function effectively in the future, but it is difficult to predict the conditions that they will need to operate under because of climate change, social change and economic changes. For this reason infrastructure needs to be adaptable and resilient, able to bounce back from whatever extreme events and general trends occur in the future. In order to achieve this infrastructure may look quite different to how it does today. We may have more renewable energy, more recycled water, and more public transport, walking and cycling, and our cities could look and operate quite differently as a result. Designing infrastructure for the future is a very complex task that needs to take into account the values, experiences and requirements of local communities and everyday people. Engineers and experts are good at developing technical solutions to well defined problems, but they have not been as successful at understanding the needs and expectations of local communities. Engineers have good methods for taking into account physical, enviromental and economic factors, but they need new tools to be able to better understand and account for social factors in their designs. Local communities will also have important roles to play in adapting to climate change and other uncertain events in the future, so it is important that local communities and engineers come together to decide what is important in designing future infrastructure. This fellowship will help Dr Sarah Bell to learn from good examples of how local communities can be involved in infrastructure decisions. Her research team will work with communities and engineers to define methods and tools to allow for better integration of community needs and ideas into infrastructure design. These tools and methods might include checklists or surveys to quickly understand what communities need and what they want for the future, calculators to help engineers working with communities to quickly calculate the environmental impacts and costs of different ideas for infrastructure, and risk assessments to understand the problems that might occur if communities are not involved in engineering design and the benefits that might be possible if they are.

High-speed rail lines, at ever increasing speeds and distances, are in development both in the UK and world-wide, but up-front capital expenditure can potentially be a major inhibiting factor both to the client and also in the eyes of the public. Cost reductions for these lines could be achievable if the initial costs of the physical construction, the duration of construction and the land take could be reduced. All three of these costs can potentially be reduced for embankments if the industry were to move towards a novel embankment replacement system. In addition embankment replacement systems could significantly improve the performance of the track structure as the dynamic properties of the contained material can be better controlled. However, such technology requires significant performance evaluation and the development of appropriate design guidance before UK industry can justifiably implement it in a project. This project therefore aims to evaluate and produce design guidance for two novel embankment replacement systems as a means to potentially reduce the cost of constructing new high-speed railway lines (particularly in urban environments) and improve the overall track behaviour and hence passenger experience.

Large-scale failures to critical national infrastructures (electricity, transportation, water, etc.), due to extreme weather events, have highlighted the need for understanding systemic risks to such infrastructures and their subsequent consequences to society, businesses and industry. The flooding and storms in UK in 2007 and 2013-14 provide evidence of the severity of such problems. Though systemic risks are important, multiple reports, including the Department for Transport's Resilience Review in 2014 highlight the lack of understanding and accountability for a network-of-networks approach to national infrastructures, with limited knowledge of systemic vulnerabilities and risks across interdependent infrastructures. Hence it is timely to develop system-of-systems national infrastructure models that inform risk assessment and resilience planning. This program of innovation proposes to develop innovative tools to support this development. The key objective of this program of innovation is to create a spatial analysis toolkit that combines data and models for multi-hazard risk and resilience estimation of interdependent national infrastructure networks. The toolkit will be used to assess and communicate risks to electricity (transmission and distribution), transport (road, rail, air and sea) networks for Great Britain and water (distribution) networks for Scotland. Through the participation of key stakeholders this program of innovation is translation-focused, has high innovation potential, is timely with high potential impact, provides value for money, and above all is relevant to the industry. The key stakeholders supporting this program of innovation include ARUP, Department for Transport, HR Wallingford, HS2, and Scottish Water, who are strategic partners with the NERC ERIIC program. Also JBA Group, a key environment consultant is involved. Project stakeholders will harness the innovation from this project to enable better targeting of resources for risk reduction and resilience planning for the critical national infrastructure.