Using technology to gain 'situational awareness'
Consortium works to improve operator understanding of alarm management
The Deepwater Horizon well explosion in the Gulf of Mexico in 2010 cost BP and its operating partners billions of dollars. High-profile accidents such as the well explosion linger in the public's mind, but behind closed doors at a typical process plant, a different kind of accident is more likely to occur.
Less-severe incidents, while not as tantalizing as an oil spill, are more likely to impact a plant's daily operations, as these types of accidents result in off-specification production and increased costs. As a response, the Abnormal Situation Management Consortium now records and tracks global industrial incidents and researches prevention methods.
The consortium's research estimates the cost of incidents to equal 3% to 8% of a company's production throughput, which makes finding a solution to these problems paramount.
Preventable factors such as an employee and work environment account for 42% of incidents. On average, between 70% and 80% of equipment problems are a result of incorrect operation of equipment. Further, the UK Health and Safety Executive, an independent watchdog organization, reports human performance impacts 70% to 80% of abnormal situations.
Recognizing that human performance is an integral component of reducing the impact of abnormal situations, the consortium focuses on understanding the implications of human performance in process operations.
If a control room operator, for example, is continuously monitoring a human machine interface (HMI) for more than eight hours at a time, the process becomes taxing on the operator’s cognitive system. A critical requirement in situations such as this is the operator’s ability to maintain high levels of situational awareness, which is the ability to perceive process information, understand a situation, and project the future status to take appropriate action.
The sophistication of a HMI
With advancements in technology and automation, process plant operations have become more sophisticated and complex. This has led to a heavy flow of process information to the control room operator through communication tools such as sensors, transmitters, analyzers, and enunciators. This immense information flow is mostly displayed to the control room operator in the form of HMI screens that feature objects with dynamic values, color changes, alarms, event lists, and pop-ups.
The time needed to process this huge information flow can lead to an unsafe environment, missed alarms, longer response times, and a higher probability of operator error. This type of unsafe environment happens because of the demand on an operator’s cognitive system to orient and evaluate the current situation, predict the future status of a process, and apply an appropriate action based on the current situation. Ultimately, information gaps such as these can reduce an operator's situational awareness.
It is essential that information systems such as operator graphics and alarm displays enhance an operator’s situational awareness. The information systems should provide a supportive context to reduce the time an operator needs to orient and evaluate a situation. The information should be cognitively and physically useable for the operator, allowing him or her to make decisions with less mental stress.
Alarm tracker: A case study
The consortium demonstrates improved alarm system performance through effective alarm rationalization methods and effective alarm system maintenance practices. But even the best efforts will not eliminate the occurrence of all alarm flooding. Effective display design techniques can help operators cope with inevitable alarm floods.
In 2009, the consortium began researching how to develop and evaluate interface techniques that could improve an operator’s ability to handle disturbances that would generate alarm flooding. The research began to focus on enhancing an operator’s situational awareness in an alarm flood situation.
In the event of an alarm flood, the list-based alarm summary display does not help the operator understand the origin of a process deviation. The operator may not understand the alarm or the root cause of the first alarm because the length of the alarm list increases quickly, and the first alarm is typically buried deep down in the list. This leads to a delay in operator response as the operator takes more time to understand which alarm should be addressed first. Even when an operator takes action, it is difficult to understand whether the original problem is resolved.
The research team developed the concept of an alarm tracker to overcome this problem. The tracker visualizes the alarms on a timeline, enhancing an operator's situational awareness through highlighting the origin of an alarm flood. This design allows an operator to see the initial alarm first, which might have been triggered by the first process deviation or the first equipment malfunction.
In addition, the alarm tracker spatially represents separate alarms by specific equipment areas. This type of visualization supports an operator's problem identification and prioritization of a problem response. The alarm tracker visualization also retains the original alarm list representation so the operator can use the list for further troubleshooting.
The consortium found that by using this visualization method, an operator's situational awareness and performance were improved. The results showed that an operator's response-to-process upsets increased by 6% with 9% fewer false-positive responses to unrelated process conditions. The evaluations further revealed the subjective rating for usability increased, and the workload subjective rating decreased.
Enhancing situational awareness
Abnormal-situation management is a challenge. Operators must deal with abnormal situations in real time, in highly complex, dynamic environments. Tools that can enhance an operator's situational awareness, such as the alarm tracker, can be deployed to help the operator manage abnormal situations safely and effectively.
Subhankar Dey is a senior marketing specialist, Anand Tharanathan is a principal research scientist, and Tom Williams is consortium director for Honeywell. For more information on the ASM Consortium, visit www.asmconsortium.net.
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