Traffic congestion is a serious threat for the economic and social life of modern societies as well as for the environment, which calls for drastic and radical solutions. The proposal puts forward an utterly original idea that leads to a novel paradigm for vehicular traffic in the era of connected and automated vehicles (CAVs) and is based on two combined principles. The first principle is lane-free traffic, which renders the driving task for CAVs smoother and safer, as risky lane-changing manoeuvres become obsolete; increases the static and dynamic capacity of the roadway due to increased road occupancy; and mitigates congestion-triggering manoeuvres. The second principle is the nudge effect, whereby vehicles may be "pushing" (from a distance, using sensors or communication) other vehicles in front of them; this allows for traffic flow to be freed from the anisotropy restriction, which stems from the fact that human driving is influenced only by downstream vehicles. The nudge effect may be implemented in various possible ways, so as to maximize the traffic flow efficiency, subject to safety and convenience constraints. TrafficFluid combines lane-free traffic with vehicle nudging to provide, for the first time since the automobile invention, the possibility to design (rather than merely describe or model) the traffic flow characteristics in an optimal way, i.e. to engineer the future CAV traffic flow as an efficient artificial fluid. To this end, the project will develop and deliver the necessary vehicle movement strategies for various motorway and urban road infrastructures, along with microscopic and macroscopic simulators and traffic management actions. TrafficFluid risk stems from the immense challenge of designing a new traffic system from scratch; however, we expect that the project will trigger a whole new path of international innovative research developments and testbeds that would pave the way towards a new efficient traffic system in the era of CAVs.