1. A method of operating a queuing system for users queuing to use a facility, the method comprising: a) providing a plurality of said facilities that can be rendered operative or inoperative depending on the number required, b) determining the number of users Q queuing to use the facility, c) determining a desired number of users N queuing to use the facility, d) determining a number Â, of users expected to arrive at the facility during a future timestep m, e) determining the expected time W taken for each user to use the facility, f) calculating by a processing system the required number S of operative facilities at time t using the ratio of the expected queue length and arrivals, to the rate of departure, such that the desired number of users N is maintained at time t+m, said ratio being given by Q 1 + A ^ N + m W ^ , ⁢ and g) rendering S number of facilities operative.