9.1 The human operator in the control loop

Most of the population will be unaware of the operators seated in front of rows of screens controlling the services we take for granted metro systems, sewage works, electricity distribution and security, for example. These operators are at the core of an electronic network of which the control room is the hub. This network will be pulsing electronic information to and from their workstations, linking them with an infrastructure that is unseen from their work positions.

The amount of information potentially accessible to each operator is tending to increase as economies of scale drive organisations to centralise their control functions and cover greater geographic areas. This increasing coverage, coupled with a drive to bring more of the network back to an individual operator, is raising new challenges as far as workloads or more precisely overload and underload are concerned. The response of systems designers and specifiers has been to use automation as a means of minimising operator workload with the underlying assumption about workload being less is better . This issue of underloading operators and maintaining them in the control loop is now emerging as the latest challenge for human factors engineers in control systems design and control room design.

The programme to upgrade the UK rail network illustrates how conflicting demands must be addressed by the human factors engineer. The rail network runs with a high level of safety but does include a mix of control systems,...