Human factors in the control room

Jet Cameron describes all the essential factors that need to be taken into account when designing safe, comfortable and effective control rooms.

Whether on a petrochemical site, air traffic control tower, nuclear power station, fire station, police station or a TV recording studio, the control room lies at the heart of the operation.

The control room operator performs a particularly demanding role in monitoring increasingly complex automated systems, where the consequence of error is potentially devastating. Control room ergonomics are therefore optimised to minimise the risk of human error.

The design of the control room must be seamlessly integrated from the outset. Whether part of a new building or the upgrade of an existing structure, the major factors that are taken into consideration include the following:
1. The control room and its operators are considered as a whole system.
2. The suitability of the structure of the control room to withstand possible major hazards events.
3. The arrangement of the numerous functions and activities within the control room.
4. The arrangement of display screens and equipment as required by a functional analysis and ergonomics standards.

Control room structure

Control rooms on petrochemical sites vary extensively in both size and location. The consequences of hazards on these sites can be devastating. The building structure must be designed to ensure that the potential hazards to the control room occupants are within acceptable limits, and are suitable for maintaining control of the plant systems both during and immediately following an incident.

Ensuring the control room’s suitability will include designing the primary structure to withstand the impact of a maximum predicted reflected blast overpressure. Materials are also carefully specified to ensure they are fire resistant for the duration of any possible fire event.

Other building elements that are carefully considered and designed to ensure the safety of occupants include the location and size of windows and minimising plant equipment on the roof. Internal fixtures are also designed to withstand vibration or movement generated by a hazard incident to prevent injury to occupants.

Control room layout

Human performance is hugely impacted by the design of the working environment. Even the most highly trained operator is subject to human error and slow response as a result of a poor control room environment. Human factors considerations are therefore integrated early into the design, commissioning and operation of the control room under both normal and abnormal plant operating conditions.

The control room arrangement must be designed to international and best practice standards to create an environment that minimises disruption to the operators, improves alertness and comfort and provides the required areas for each function.
The combination of, and interaction between, people and equipment can determine overall operator comfort, which is why considering the control room and its operators as a whole system is important.

For example, display screens positions are optimised for maximum comfort and to ensure that critical information is located within an operator’s ‘primary display zone’ and that controls are positioned within intuitive reach. These considerations contribute to an environment that enables operators to remain alert throughout their shift and to be responsive to alarms and potential incidents.

Key elements of control room design include the following:
- The control room layout must be derived from an appropriate task analysis to ensure the user requirements for movement patterns are met.
- Necessary lines of sight and communication are uninterrupted to aid team working.
- Location of the control room within the building must be considered to minimise unnecessary movement through the control room.
- Temperature, airflow and lighting are adjustable to suit individual preference and external factors. Adjustable lighting to replicate warm and cold light can assist the operators to maintain regular body rhythms.
- The acoustic environment is considered to ensure clarity of communication and noise is kept to optimum level without prolonged low or high frequency noises.
- The design of the Human Machine Interface must be based on a full task analysis to ensure no over or under arousal of mental workload when dealing with specific tasks.
- Any alarms in place should be clear, based on existing conventions and not be confused with other alarms.
The anthropometry of the control desks, panels and seating should suit operators and be suitable for 24 hour use to avoid problems with posture.

ISO 11064 Ergonomic design of control centres part 1 to 7 sets the standards for the design principles of any control room. The document is one of the key tools utilised to ensure the design of new control rooms and the refurbishment of existing control rooms, to provide the appropriate environment to support the high pressure role of the operator and to minimise the risk of human error due to poor design

Precision design is required, with modern systems providing operators with immediate control, even integrating touch screen technology. The methodologies, for both structural design and ergonomic requirements, can and should be applied to all control rooms where maximum operator comfort and alertness is paramount to minimise human error and response times.

By Jet Cameron, an architectural team leader at IKM Consulting.

This article was first published in issue 522 of The Ergonomist, December 2013

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