“Is it possible, for example, to have a city where potholes get fixed autonomously, before they become dangerous and expensive?”

In the Financial Times* Mark Miodownik, a professor of materials and society at University College London, asks this question. He reports on research which aims to create materials and engineering systems so complex that they can sense when they are damaged and are able to repair themselves. His article is summarised here.

The main drivers of such self-healing technology are economic and environmental.

The 20th century saw the invention of “smart” materials that could respond to changes in their environment. For example, shape memory alloys were discovered that respond to heat by changing shape. These are used in many walks of life, from windows that open automatically when a building gets too hot, to surgical operations where heat expands the shape of an implant so it fits exactly.

The aerospace industry has been developing self-healing composites to deal with microscopic cracks that grow in aircraft fuselages. Such self-healing materials improve safety, increase the lifespan of the aircraft and so reduce costs.

A drone, equipped with the ability to repair a leaky drain, could save millions on the repair and maintenance bill of cities These technologies work by incorporating microcapsules of liquid resin inside the material and by coating the reinforcing fibres inside the composite with a catalyst. If a crack forms, the microcapsules burst open and liquid resin flows into contact with the fibres. The catalyst then causes the resin to solidify rapidly and heal the crack. At present, this only works for micro-cracks because the capsules are so small.

Infrastructure is a major area for self-healing materials. In the UK alone, it is estimated that the repair and maintenance of structures costs £40bn a year and during these repairs the services provided by such infrastructure become unavailable. On rail and road networks, this leads to disruption, economic impact and pollution due to traffic jams.

A major project funded by the UK’s Engineering and Physical Sciences Research Council, led by Leeds University, with engineers from Southampton, Birmingham and Mark Miodownik’s institute at University College London all part of a research consortium.

See https://www.birminghammail.co.uk/news/midlands-news/how-potholes-roads-causing-more-13034551

Consider an alternative future, where information from a driverless vehicle that continually surveys the city infrastructure identifies the pothole at an early stage. The information of the size and shape of the nascent pothole is relayed to another autonomous vehicle, which is deployed at night when traffic flow is low. It locates the pothole, stops for a few minutes using hazard lights, and then uses a 3D printer to deliver tar to precisely repair the hole. Repairing it at an early stage saves money by preventing the congestion caused by road closure.

Leeds City Council is making the Yorkshire city a test-bed for the new technologies. The city is painfully aware of how much of its annual budget goes on repair and maintenance —tens of millions of pounds. It sees that creating autonomous repair systems that act as a metropolitan immune system will slash the bill drastically.

*https://www.ft.com/content/9870fa7a-314d-11e8-b5bf-23cb17fd1498, paywalled