Sprayed concrete lined (SCL) tunnels are growing rapidly in popularity due to their versatility. The design and construction of both hard rock and soft ground tunnels has been revolutionised by the advent of the SCL method and now the use of permanent sprayed concrete linings has unlocked the true potential of the method to minimise construction costs and times. Yet the complex early age behaviour of the sprayed concrete makes the design difficult and requires a robust management system during construction. Consequently the great advantages of the method must be balanced against the risks, as...