A Human Performance Modeling System for Process Safety Operations

Operators have a crucial role in case of an emergency in a process facility. When an abnormality occurs in the process, the operator has a limited time to take corrective actions before system safety devices shut down the operation. It is crucial that system designers and safety professionals know about this required time frame before operations are initiated. Specific research goals for this project include the following: * Estimating the standard time data for operators to take corrective actions in emergency situations. * Developing a modeling system, to allow design/process engineers to find the standard time required for the operator(s) to respond in emergency situations. Current standard time data for carrying out tasks cover normal, steady state cases. However, the time required to take action in emergency situations is different than normal cases. Because of the possibility of a process incident and danger, operators make corrective actions faster compared to normal cases. Therefore, current standard time data do not meet the requirement for emergency situations. Shorter standard time data for emergency situations needs to be estimated. Standard time data for emergency situations is estimated by using time studies. Various time study methods were introduced and discussed. MODAPTS is a predetermined time standard method and stands for Modular Arrangement of Predetermined Time Standards, and was used in this project because it is reliable, easy to use and consistent. The methodology adopted for the study required observing several emergency case videos. The operations were decomposed into basic motions (such as walking, hand movement, bend and arise, etc.) by using a video player’s frame by frame feature. The amount of time required to take these basic motions was estimated. These estimated times were then compared to calculations based on MODAPTS, which is a predetermined time standard system. By comparing MODAPTS’s standard time intervals with those estimated from emergency situations, ratios or coefficients have been estimated for the various basic motions (e.g., factors such as 0.9, 0.75, etc.). The estimated coefficients for emergency situations, which are generally around 0.65, were used in developing a modeling system. The user of this modeling system can estimate the required time to take corrective actions in emergency situations as long as he/ she knows the actions need to be taken. Consequently, the time required to take necessary actions in emergency operations will be designed and evaluated in a systematic way to reduce the potential, as well as duration, of an incident