Reliable drainage solutions are critical for ensuring the long-term and cost-effective provision of railway infrastructure. Water plays a significant role in the degradation of railway infrastructure and can cause poor track geometry and accelerated deterioration of ballast, with high associated maintenance and repair costs which inevitably get passed on to the end-user. Excessive amounts of water may also cause catastrophic failure of railway infrastructure systems, which represent a real threat to public safety. Climate change is predicted to result in more extreme weather and flash flood events. The railway drainage systems will therefore be put under severe strain with increased likelihood of disruption to rail services. Much of the UK railway drainage infrastructure is old and in need of repair or replacement. However, the UK railway industry is experiencing significant growth in the number of passengers and the amount of freight carried, which reduces the opportunities available to carry out maintenance. In light of these issues, railway drainage system modernisation is considered to be a key factor for improving railway network safety and capacity, and ensuring the infrastructure's resilience to changing weather and climate events. This project focuses on providing novel and easily installed railway drainage solutions which make use of lightweight and cost-effective 'new materials'. 'New materials' includes those recently developed as well as materials that can be newly applied within drainage systems. The project will consider a range of materials for use in this application, such as Expanded Polystyrene (EPS) which is a lightweight and strong material with good chemical resistance. The project includes a range of experimental testing, including trials of a new material drainage system within a full-scale railway track model, as well as advanced small-scale physical modelling using the University of Nottingham geotechnical centrifuge. Numerical models will also be developed to gain a better understanding of the effects of key parameters within the drainage system. An important component of the project is the development of tools which will allow for the assessment of the full lifecycle costs of the developed new material drainage solutions. These tools have the potential to help railway operators make informed decisions relating to the selection of track and drainage system maintenance and repair solutions. Advanced tools will also be developed which will provide a better understanding of the inter-relationships between railway drainage performance and other railway systems, including other infrastructure assets and operation services. The project benefits from the involvement of experts from railway industry, including URS, a leading provider of engineering, construction and technical services within the railway sector, and ASPIN, who provide a range of consultancy services to the railway industry. The project will also benefit from access to information from Network Rail, the owner of the UK railway infrastructure, through proven links between the research team and representatives from Network Rail. The project fosters a multi-disciplinary approach to developing engineering solutions, with expertise from several technical areas, including geotechnics, transportation infrastructure design and performance as well as asset management. The successful completion of the project will allow the development of modern railway drainage solutions which incorporate new lightweight, easy to install, and cost-effective materials. The lifecycle cost assessment tools developed as part of this project will enable railway operators to make informed decisions about railway maintenance and repair, and ensure that end-uses of the railway get the best service possible.

Targeted under NERC's Water theme, the proposed project is aimed at determining the fate, reactivity and environmental risk of deploying nanoscale iron particles (INP) for the cleanup of polluted sites and groundwaters around the UK. The project is CASE supported by URS/Scott Wilson with advisory input from DEFRA (Dr Helinor Johnston) and CL:AIRE (Dr John Henstock). The Problem: The increased development and use of engineered nanomaterials has the potential to offer great benefits to society through their exploitation within numerous products developed by diverse industries. Some applications of nanomaterials have the potential to afford environmental benefits and of particular interest is the use of nanoscale particles of zerovalent iron (INPs) for the in situ cleanup of contaminated land and groundwater. Theoretical and practical evidence suggests that these INPs can be used to rapidly remediate contaminated sites at a significantly reduced cost relative to conventional methods. Most significantly they are also applicable for a wide range of hazardous chemicals, including polychlorinated biphenyls (PCBs); heavy metals and even radionuclides. To date the UK government has adopted a precautionary approach to the deliberate release of nanomaterials into the environment and consequently the use of INP remediation technology is not currently permitted by the UK Environment Agency. In July 2010 DEFRA commissioned a study (CB0440) to evaluate whether the hypothesised or known detrimental effects associated with the intentional release of INPs into the environment, outweigh the benefits that may be realised by using INP for site cleanup. Whilst this study has not yet been completed, a recent detailed review provided by the Bristol group has highlighted that much is still unknown about the true geochemical fate of INP injected into the subsurface, their true efficiency for cleanup of pollutants and the level of impact they may have on the environment. The Solution: By partnering academia with industry, the current project proposes to bridge the gaps in our current understanding and provide valuable site-derived data relating to the lifecycle of INPs in the environment. The project will build upon existing links between the Bristol Interface Analysis Centre (IAC), a group with the strongest UK track record for INPs research, and URS/Scott Wilson, an internationally renowned geotechnical and geoenvironmental engineering consultancy. Over the period of the project, the student will perform both laboratory and field-based investigations using INP of different sizes and types (wet-formed, dry-formed, annealed, surfactant coated) to evaluate their relative performance for contaminant remediation in natural waters of complex geochemistry. The project will also seek to better understand specific fundamental lifecycle aspects of INP injected into pore-water systems, specifically the factors that control transport, transformation, contaminant-INP reactivity and microbial impact. Of specific value to the project, URS/Scott Wilson will provide access to contaminated sites within the UK and/or overseas where the student, under supervision of the CASE supervisor, will participate in the planning, deployment and monitoring of a remediation project using INP. In the UK the student will also have access to a specialist 50m3 hydrogeochemical test cell located at URS/Scott Wilson's laboratories in Nottingham, where groundwater remediation systems using INP's will be prototyped and optimised. It is considered that the current studentship, which will be advised by both DEFRA and CL:AIRE, will produce data and practical knowledge that will help to shape future UK legislation and industry best practice for the use of INP in site clean-up.

This experimental project will address the problem of wheel track rutting that develops in asphalt road pavements under repeated traffic loading. A new torsional Hollow Cylinder Apparatus will be developed to reproduce, more accurately than hitherto, the field loading regime in the laboratory, so that high quality measurements can be made of the permanent strain that accumates under cyclic loading. Collaboration with the University of California at Berkeley and at Davis will allow use to be made of their established but less accurate asphalt shear testing equipment using identical material. Pilot scale wheel tracking tests will be conducted in the Nottingham Pavement Test Facility to generate rutting performance data and use will be made of full scale test data from the Californian team. The outcome of the project is aimed at improving prediction methods for rut development in asphalt pavements and to assess the reliabilty of a simple practical test for use by industry to estimate the rut resistance of asphalts.

Construction using geosynthetics offer savings both in terms of cost and embodied carbon. However, their application is limited by poor understanding of geosynthetic soil interaction, resulting in at best over conservative designs and at worst failures resulting in uncontrolled contamination and loss of life. This fifteen month project will use digital imaging and rapid prototyping to create higher strength interaction between geosynthetics and adjacent materials, allowing steeper, higher and safer slopes to be constructed, thus facilitating sustainable construction using these materials. In barrier systems, geomembranes are typically placed, as part of multilayer systems, over low permeability clay to create a composite barrier benefiting from the low permeability of the geomembrane and attenuation properties of the clay. The geomembrane is then overlain by a geotextile or sand to project it from puncture and damage from the overlying material. This project will allow design of geomembrane surfaces for interaction with these adjacent materials. The designed interfaces will have greater peak strength and allow designers to understand and specify the characteristics of interface shear strength beyond simply the height of the surface texturing (asperity height). In practical terms it will allow higher and steeper slopes when using geomembrane barrier systems, offering improved project profitability and safer use across all applications. The upper bound interface shear strength is controlled by the material adjacent to it. For a geosynthetic-soil interface this is the strength of the soil. For a geomembrane-geotextile interface the maximum strength will be controlled by the internal bond and fibre strength of the geotextile. The role of the texturing is to transfer the stresses into the adjacent material. The "one size fits all" approach of 0.25mm asperity results in the same texturing being used for interactions with fine grained soils, coarse grained soils and geotextiles and also at low and high confining stresses. The main gaps in knowledge to be addressed are as follows: 1. What are the physical mechanisms that develop peak strength in geomembrane-soil and geomembrane-geosynthetic interfaces? 2. How do these mechanisms differ for interactions with geotextile, coarse grained soil and fine grained soils? 3. Can the nature of the geomembrane surface be designed to better transfer and distribute load, to produce an interface with higher strength? The project will use scanning electron and optical microscopes to study material interaction to determine how peak strength is mobilised and from these studies produce CAD models of high strength interfaces. The CAD models shall be converted into physical models through 3D printing allowing their interaction with soils and geotextiles to be observed and quantified. The work will allow design of geomembrane surfaces for interaction with typically used materials. The designed interfaces will have greater peak strength and allow designers to understand and specify the characteristics of interface shear strength beyond simply asperity height. In practical terms it will allow higher and steeper slopes when using geomembrane barrier systems offering improved project profitability.

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.