Gravity measurements exert a particular fascination ranging from the everyday experience of feeling the gravitational force holding us on ground to the mysteries of general relativity and space time. Compared to other forces gravity is surprisingly weak, making shielding of gravitation practically impossible. Gravity measurements are ideally suited to look deep inside the ground and they have been used for over 100 years in fields as oil and mineral exploration, underground mapping and climate research. However, although gravity measurements are highly valued, there are some drawbacks in terms of long and tedious measurements and geological noise. GG-TOP responds to an increasingly pressing demand for a holistic development programme driving sensitivity of instrumentation, modelling instrument and geological noise, discriminating underground objects, fusing and presenting the information from multi-sensor systems. The GG-TOP consortium is truely multi-disciplinary uniting fundamental and applied physicists, civil and electrical engineers and archaeologists behind a joint goal. GG-TOP has a strong Stakeholder compontent with interactions at all levels and potential users directly influencing the research programme. GG-TOP will explicitly evaluate the potential of its new technology in applications as diverse as urban infrastructure (pipes, cables...) and void (cellars, tunnels,..) mapping, seabed inspection, archaeology and fundamental tests of physics. We anticipate the outcome of this programme to be a technology suite adaptable to various needs and leading to a range of follow-on product development programmes.

Our vision is that of a city where infrastructure is autonomously maintained and dynamically responsive, focused on: securing the health & wellbeing of its citizens; contributing to flourishing and sustainable natural systems in the city; and creating positive economic and societal outlooks. Towards our vision we will tackle the Grand Challenge of: Zero disruption from Streetworks in UK Cities by 2050. Our strongly interdisciplinary team aspires to fulfil our Grand Challenge through pioneering scientific research (and research methods) into: autonomous systems for minimally invasive infrastructure sensing, diagnosis and repair; development of advanced robots for deployment in complex live city environments; and the socio-technical intricacy of the robot - human - natural systems interfaces. We will develop pioneering robot designs, technical implementations and socio-economic impact cases linked to specific application requirements, starting with three case-study systems: o "Perch and Repair" remote maintenance and modernisation of lighting columns to promote their use as multifunctional platforms for city communication nodes; o "Perceive and Patch" Swarms of flying vehicles for autonomous inspection, diagnostics, repair and prevention of highway defects (e.g. potholes); o "Fire and forget" hybrid robots designed to operate indefinitely within live utility pipes performing inspection, repair, metering and reporting tasks.

In Europe, the total value of sewer assets amounts to 2 trillion Euros. The US Environmental Protection Agency estimates that water collection systems in the USA have a total replacement value between $1 and $2 trillion. Similar figures can be assigned to other types of buried pipe assets which supply clean water and gas. In China alone 40,000 km of new sewer pipes are laid every year. However, little is known about the condition of these pipes despite the pressure on water and gas supply utility companies to ensure that they operate continuously, safely and efficiently. In order to do this properly, the utility operator must identify the initial signs of failure and then respond to the onset of failure rapidly enough to avoid loss of potable water supply, wastewater flooding or gas escape. This is attempted through targeted inspection which is typically carried out through man-entry or with CCTV approaches, although more sophisticated (e.g. tethered) devices have been developed and are used selectively. Nevertheless, and in spite of the fact that the UK is a world leader in this research area, these approaches are slow and labour intensive, analysis is subjective, and their deployment disrupts traffic. Moreover, because these inspections are necessarily infrequent and only cover a small proportion of the pipe network, serious degradation is often missed and pipe failures occur unexpectedly, requiring emergency repairs that greatly disrupt life of the road and adjacent buried utility infrastructure. This Programme Grant proposes a radical change in terms of buried pipe sensing in order to address the issues of pipe inspection and rehabilitation. It builds upon recent advances in sensors, nano- and micro-electronics research, communication and robotic autonomous systems and aims to develop a completely new pervasive robotics sensing technology platform which is autonomous and covers the entire pipe network. These robots will be able to travel, cooperate and interrogate the pipes from the inside, detect the onset of any defects continuously, navigate to and zoom on sub-millimetre scale defects to examine them in detail, communicate and guide any maintenance equipment to repair the infrastructure at an early sign of deterioration. By being tiny, they do not present a danger of being stuck, blocking the pipe if damaged or run out of power. By being abundant, they introduce a high level of redundancy in the inspection system, so that routine inspection can continue after a loss of a proportion of the sensors in the swarm. By making use of the propagation of sonic waves and other types of sensing these robots can monitor any changes in the condition of the pipe walls, joints, valves and lateral connections; they can detect the early development and growth of sub-millimetre scale operational or structural faults and pipe corrosion. An important benefit of this sensing philosophy is that it mimics nature, i.e. the individual sensors are small, cheap and unsophisticated, but a swarm of them is highly capable and precise. This innovation will be the first of its kind to deploy swarms of miniaturised robots in buried pipes together with other emerging in-pipe sensor, navigation and communication solutions with long-term autonomy. Linked to the related previous work, iBUILD (EP/K012398), ICIF (EP/K012347) and ATU's Decision Support System (EP/K021699), this Programme Grant will create the technology that has flexibility to adapt to different systems of governance globally. This work will be done in collaboration with a number of industry partners who will help to develop a new set of requirements for the new pervasive robotic sensing platform to work in clean water, wastewater and gas pipes. They will support the formation and operation of the new research Centre of Autonomous Sensing for Buried Infrastructure in the UK and ensure that the results of this research have strong practical outcomes.

The surface urban transport infrastructures - our roads, cycle ways, pedestrian areas, tramways and railways - are supported by the ground, and hence the properties of the ground must control to a significant degree their structural performance. The utility services infrastructure - the pipes and cables that deliver utility services to our homes and which supports urban living - is usually buried beneath our urban streets, that is it lies below the surface transport infrastructure (usually roads and paved pedestrian areas). It follows that streetworks to install, replace, repair or maintain these utility service pipes or cables using traditional trench excavations will disrupt traffic and people movement, and will often significantly damage the surface transport infrastructure and the ground on which it bears. It is clear, therefore, that the ground and physical (i.e. utility service and surface transport) infrastructures exist according to a symbiotic relationship: intervene physically in one, and the others are almost inevitably affected in some way, either immediately or in the future. Moreover the physical condition of the pipes and cables, of the ground and of the overlying road structure, is consequently of crucial importance in determining the nature and severity of the impacts that streetworks cause. Assessing the Underworld (ATU) aims to use geophysical sensors deployed both on the surface and inside water pipes to determine remotely (that is, without excavation) the condition of these urban assets. ATU builds on the highly successful Mapping the Underworld (MTU) project funded by EPSRC's first IDEAS Factory (or sandpit) and supported by many industry partners. The MTU sandpit brought together a team that has grown to be acknowledged as international leaders in this field. ATU introduces leaders in climate change, infrastructure policy, engineering sustainability and pipeline systems to the MTU team to take the research into a new sphere of influence as part of a 25-year vision to make streetworks more sustainable. ATU proposes to develop the geophysical sensors created in MTU to look for different targets: indications that the buried pipes and cables are showing signs of degradation or failure, indications that the road structure is showing signs of degradation (e.g. cracking, delamination or wetting) and indications that the ground has properties different to unaltered ground (e.g. wetted or eroded by leaking pipes, loosened by local trench excavations, wetted by water ingress through cracked road structures). For example, a deteriorated (fractured, laterally displaced, corroded or holed) pipe will give a different response to the geophysical sensors than a pristine pipe, while wetting of the adjacent soil or voids created by local erosion due to leakage from a water-bearing pipe will result in a different ground response to unaltered natural soil or fill. Similarly a deteriorated road (with vertical cracks, or with a wetted foundation) will give a different response to intact, coherent bound layers sitting on a properly drained foundation. Taking the information provided by the geophysical sensors and combining it with records for the pipes, cables and roads, and introducing deterioration models for these physical infrastructures knowing their age and recorded condition (where this information is available), will allow a means of predicting how they will react if a trench is dug in a particular road. In some cases alternative construction techniques could avert serious damage (e.g. water pipe bursts, road structural failure requiring complete reconstruction) or injury (gas pipe busts). Making this information available will be achieved by creating a Decision Support System for streetworks engineers. Finally, the full impacts to the economy, society and environment of streetworks will be modelled in a sustainability assessment framework so that the wider impacts of the works are made clear.

The Hub will create a seamless link between science and applications by building on our established knowledge exchange activities in quantum technologies. We will transform science into technology by developing new products, demonstrating their applications and advantages, and establishing a strong user base in diverse sectors. Our overarching ambition is to deliver a wide range of quantum sensors to underpin many new commercial applications. Our key objective is to ensure that the Hub's outputs will have been picked up by companies, or industry-led TSB projects, by the end of the funding period. The Hub will comprise: a strong fabrication component; quantum scientists with a demonstrated ability to combine scientific excellence with technological delivery; leading engineers with the broad collective expertise and connections required to develop and use new quantum sensors. We have identified, and actively involved, industry enablers to build a supply chain for quantum sensor technology. As well as direct physics connections to industry, the engineers provide strong links to relevant industrial users, thus providing information on industrial needs and enabling rapid prototype deployment in the field. To establish a coherent national collaborative effort, the Hub will include a UK network on quantum sensors and metrology, which will also exploit the connections that Prof Bongs and all Hub members have forged in Europe, the US and Asia. This inter-linkage ensures capture of the most advanced developments in quantum technology around the world for exploitation by the UK. Quantum sensors and metrology, plus some devices in quantum communication, are the only areas where laboratory prototypes have already proven superior to their best classical counterparts. This sets the stage, credibly, for rapid and disruptive applications emerging from the Hub. The selection of prototypes will be driven by commercial pull, i.e. each prototype project within the Hub must demonstrate, from the outset, industry or practitioner engagement from our engineering and/or industrial collaborators. We have strong industry support across several disciplines with the structures in place actively to manage technology and knowledge transfer to the industry sector. Particular roles are played by NPL and e2V. We will closely collaborate with NPL as metrology end-user on clock, magnetometer and potentially Watt balance developments with a lecturer-level Birmingham-NPL fellow contributed by Birmingham University and our PRDAs spending ~17 man-years in addition to 3-5 PhD students on these joint projects in the Advanced Metrology Laboratory/incubator space. E2v have a unique industrial manufacturing/R&D facility co-located within the School of Physics and Astronomy at Nottingham that has already catalysed the expansion of their activities into the Quantum Technology domain. Public Engagement conveying the Hub's breakthroughs will be a high priority - for example annually at the Royal Society Summer Exhibitions. In addition to cohort-training of 80 PhD students working within the Hub, the Hub will contribute to the training of ~500 PhD students via electronically-shared lectures (many already running within the e-learning graduate schools MPAGS, MEGS, SEPNET and SUPA) across the institutions within the Hub. The Hub will create an internationally-leading centre of excellence with major impact in the area of quantum sensors and metrology. To widen the impact of the Hub and ensure long-term sustainability, we will actively pursue European and other international collaborative funding for both underlying fundamental research and the technology development.