Urban areas contain not only significant concentrations of both railway infrastructure, but also elevated temperatures due to the urban heat island effect. During the summer months, this can often mean that track and lineside assets in cities breach critical temperature thresholds resulting in localised failures on the network. Whilst the rest of the track remains fully serviceable, the interdependent nature of the system means that asset failure at critical nodes (i.e. in urban areas) propagate throughout the rail network causing extensive delays, passenger dissatisfaction, and a disproportionate additional cost than the original fault itself. Examples of such impacts were clearly highlighted during the recent 2013 heatwave which caused the much publicised track-buckle at London Waterloo and track-circuit malfunction at Edinburgh Waverley. In order to manage the heat risk, blanket speed restrictions are often imposed above pre-defined temperature thresholds to ensure passenger safety. The delays caused due to direct failures or, more commonly, speed restrictions are not only disruptive to passengers, but they also cost Network Rail significant money in the form of Schedule 8 payments (i.e. fines) to the train operating companies that use the infrastructure. This proposal explores whether the existing temperature thresholds used for heat risk management are appropriate. In particular, it focuses on determining the feasibility of dynamic thresholds which increment over the course of the summer season. The rationale for this is that failures are 'harvested' during hot spells and hence the first heatwave of the year highlights network vulnerability, with subsequent heatwaves (unless significantly hotter) being less problematic. This approach represent a radical and innovative solution to reduce the number of blanket speed restrictions presently used in the industry, the significance of which will become even more apparent when the consequences of climate change on the network are factored into the analysis.

The rail sector is of great and growing importance to the economic and social functioning of the UK. Passenger usage has increase by over 50% compared to 2002-2003, with the amount of freight carried growing at a similar rate (Office of Rail Regulation, 2015). In maintaining a reliable service, Network Rail (NR) faces the twin challenges of responding to the impacts of weather events on a day-to-day basis whilst planning and implementing long-term adaptation work. Of critical importance to informing targeted cost-effective actions at both timescales is a better understanding of what the DfT Brown Review (2014) termed 'single-points of failure': critical sections of the rail network which have large scale impacts for society and economy, as exemplified by the collapse of the Dawlish Sea Wall in February 2014. This project aims to produce a transformative data-driven approach to map the criticality to weather-induced natural hazards as a fundamental step in both improved extreme event management and climate change adaptation prioritisation. Key to this is an expert-led metric for network criticality which can be used to identify the most critical locations on the network. This will allow NR to determine where adaptation work will have optimal benefit, whilst also aiding the allocation of resources and operational decisions during extreme events, reducing disruption-related costs and improving service to customers. The project has the following objectives: 1. Define the key determinants of criticality from Network Rail's perspective. 2. Formulate a criticality metric based on the determinants identified in objective 1. 3. Demonstrate the metric on a Network Rail route and identify network-critical sections of track. 4. Elicit views on implications for adaptation actions and extreme event management. The results are designed to be applicable to the entirety of NR's network and would inform decisions made on the 20,000 miles of track and 2,500 stations that NR owns and operates. To be cost-effective, the utilisation of the metric will need to enable a reduction in network disruption of around 0.1-0.2%, achieved through smarter allocation of resources/adaptation actions to those areas where the consequences of weather-related incidents in terms of network disruption is greatest. We believe that by integrating the results of this project into the existing NR systems described above, the company will be able to target conservatively a reduction of 3-5% of weather-related disruption, which would yield annual savings of £1.5-£2.5 million. These direct savings to NR would be multiplied further by the full economic savings to UK PLC, contributing to improved national productivity, and would also have impact on non-monetised benefits to society through more resilient mobility. Keywords: extreme weather; climate change; rail transport; disruption; resilience; business continuity

Distributed fibre optic acoustic and dynamic strain sensing has important applications in the security, energy, environment and transport industries. Examples of such applications include intruder detection, leak detection in oil/gas pipelines and nuclear power reactor systems, monitoring shock waves caused by fracking, and tracking and listening to moving trains. The key advantage of all distributed fibre optic sensing is that a measurand can be detected at every point along the fibre. In this way a large number of discrete sensors can be simply replaced by a single optical fibre. The basic operation is based on sending pulses of light down the optical sensing fibre and detecting the changes in the backscattered light, caused by the parameters to be measured. The Rayleigh backscattered light is sensitive to the sound pressure induced strain on the fibre. Since each point on the Rayleigh backscattered trace corresponds to one section of the sensing fibre, the acoustic wave field along the sensing fibre can be mapped by launching optical pulses into the sensing fibre at a regular intervals and monitoring the changes in the backscattered traces. With the appropriate optical setup and the digital signal processing that we have developed, the acoustically induced strain in terms of its frequency, phase and amplitude can be spatially resolved along the entire length of the sensing fibre. The repetition rate of the pulses determines the frequency at which the measurement is repeated and hence the detection bandwidth of the acoustic signal. In essence, the single optical fibre can perform the same function as multiple (~10000) microphones but with much reduced cost and complexity of installation. The proposed research is to develop a distributed fibre optic acoustic and dynamic strain sensor technology with capabilities far in excess of what has currently been achieved in order to improve its applicability to a number of key applications, but in particular to the rail transport industry for monitoring the health of track and trains. The improvement will stem from modification of the optical configuration and introduction of new hardware and software for data handling and processing. Whilst future predicted growth in rail travel will inevitably require additional growth in rail infrastructure, it is imperative that the industry continues to strive to improve the efficiency of existing train services, whilst maintaining the highest of safety standards. This proposal is concerned with developing the state of the art distributed fibre optic acoustic sensing and with the goal of enabling i) Accurate determination of the location and speed of trains which will allow train density to be optimised; ii) Abnormal sounds to be detected, providing early indication of potential problems such as intruders, cable theft, loose and rattling components, etc, facilitating timely maintenance or preventative action to minimize disruptions; and iii) The condition of track-side machines such as level crossing motors and remote generators to be monitored, ensuring safe and efficient operation. Achieving these goals will help to provide safe, efficient and reliable rail transport that maximises the capacity of the existing infrastructure.

Under the effect of climate change, increasingly intense rainfall has caused frequent failures of UK transport infrastructure slopes/embankments. These failures have severely disrupted the serviceability of the transport network (which are vital in supporting national economic growth) and consequently led to significant socio-economic losses. There have been challenges for the engineers, planners and stakeholders to devise environmentally-friendly stabilisation techniques to withstand the negative impact of irreversible environmental change, while at the same time protecting the natural environment/ecosystems, which underpin the economic prosperity, health and wellbeing of society. Various slope stabilisation methods have been developed, such as sprayed concrete cover and piling. However, these traditional "hard" engineering methods have high embodied CO2, resulting in greenhouse gas emissions that have been linked to further increased climate change. This emphasises the urgency to develop a low-carbon and more sustainable engineering solution that can increase resilience and protect vital transport embankments. The slope bioengineering method (SBM) using stem cuttings (known as live poles) is an aesthetically-pleasing, environmentally- and ecologically-friendly alternative to the traditional "hard" engineering methods, as this technique provides additional environmental and societal benefits of carbon fixation, enhanced biodiversity and ecosystem restoration within the built environment. Plant roots provide direct mechanical stabilisation to embankments and also act as a "bio-pump" during transpiration to remove soil moisture, which in turn increases soil strength and, hence, embankment stability. However, seasonal variation of soil suction due to plant transpiration potentially results in ground surface settlement/heave, which disrupts the serviceability of embankments (e.g. train speed restriction and delay, poor railway track quality and maintenance). Such disruption is more prominent when embankments are made of clay material that is vulnerable to shrinkage/swelling upon soil moisture changes. An interesting question hence arises: Is SBM suitable to be applied to clay fill embankments, and is it capable of maintaining slope stability and preventing from excessive slope deformation simultaneously? The project will evaluate critically the effectiveness of SBM to combat the influence of different climate-change scenarios on the performance of clay fill embankments. The work described in this proposal represents the first systematic physical model tests for small-scale model embankments (made of real soil) supported by novel water-uptake pole models within a geotechnical centrifuge. The pole models will be designed to have similar strength and stiffness to real poles, and will also be capable of simulating the effects of plant root-water uptake in the soil. Highly-instrumented centrifuge tests are designed to investigate holistically whether the change of the soil water regime due to root-water uptake in a bioengineered embankment magnifies the clay shrink-swell response, which in turn leads to seasonally-driven failure and ground surface settlement/heave. Different vegetation management schemes (through selection of plant types and arrangements) will also be examined to optimise the performance of embankments for minimising ground surface settlement, while enhancing embankment stability. The project will provide a unique test database that contains new knowledge for end users to develop increased confidence for wider deploying SBM in practice. The new knowledge and insight derived from this project will not be limited only to transport infrastructure slopes/embankments, but extends also to wider engineering applications. These include enhancing the performance of earthworks for flood defence and landfill covers, which are critical elements of civil infrastructure that are vulnerable to the effects of climate change.

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.