Impact of Functional and Schematic Overview Displays on Console Operators’ Situation Awareness

Abstract

Console operators in process plants have to maintain a high level of situation awareness to operate the plant safely, effectively, and efficiently. An overview display is one of the primary displays in a control room that operators monitor to gain and maintain an understanding of the plant. In this study, the authors evaluated operator performance using two overview display formats. The first format, characterized as a functional design, included qualitative, graphical indicators for process parameters and organized the position of the indicators on the basis of functional relations of the process equipment. The second format, characterized as a traditional schematic display, showed connecting process lines between equipment and numerical fields to present process information. Both displays contained the same indicator values. Eighteen plant operators used both display formats to monitor a crude unit process for process parameters that deviated from normal values. We measured operators’ situation awareness using think-aloud protocols and situation awareness global assessment technique, subjective workload, and usability ratings. Results indicated that operators’ situation awareness was significantly higher when they monitored the process on a functional display compared with a schematic display. Their subjective workload and usability ratings also favored the functional overview display format. Implications of the findings for continuous process control and overview display design are discussed.