The future Large-Scale Ultra-Complex Engineering Systems (LUES) are envisaged to be beyond the size of systems of today such as avionics systems, control and monitoring systems of large chemical plants, national telecommunication network, national economies, etc. A good example of such a system (LUES) is in the concept of the City of the Future. Cities of the Future – unlike Smart Cities which are largely an ICT retrofit of the constituent legacy systems (electric energy grid, communication networks, transportation system, etc.) – are going to be predominantly designed from scratch to a specification. At least the kernel of the urban ecosystem; followed by a subsequent continuous growth at the fringes governed by somehow semi-chaotic and conflicting requirements of different stakeholders. The world wide web can be regarded to some extent as a precursor of a LUES.
Large-scale systems in operation today are mostly the result of engineering practice accumulated over decades of the development. Little science may have been involved in their development as systems. In this context, the scientific knowledge the design of large systems is based on may be of limited value for the design of future large-scale ultra complex engineering systems.
Large-scale ultra complex engineering systems are going to pose a challenge for the design, design validation, system operation, and evolution. Actually, the nature and extent of that challenge is not clear yet as no systems of that nature have (probably) been developed to date.