Mental Workload Capacity in Railway Engineers

Because a human's mental workload is limited, the amount of mental workload a job exhibits on the operator can directly influence the performance. Along with the nature of non-stop, time-sensitivity of the railway system, and safety priorities, railway crews exhibit a high mental workload level when operating the railway. Working memory makes a large part of the mental workload, and it is always used to make decisions, whether to perceive stimuli or retrieve prior experiences from long-term memory. A decrease in working memory will take a toll on mental workload and affect decision-making, problem-solving abilities, and eventually performance. The poor performance then leads to errors and tragedy. To better improve cognitive workload, systemic feedback is shown to reduce mental workload significantly.

Factors Influencing Working Memory

In 2008, two metro links collided and derailed because one railway engineer failed to notice the red signal because he was texting on his cellphone (Lauter, 2021). One contributor to excessive working memory load is multitasking. Although not as much as driving or piloting, railway engineers also utilize a large mental workload during operation. According to Kazemi et al. (2016), train engineers need to remember, recall, think ahead, and consider how different factors impact the train under little time while controlling the train and maintaining vigilance for long hours. They need to be familiar with the route, know where to speed and slow with turns, and communicate with the conductor while noticing any signals for the slow down or red light and monitoring the system. With the already heavy mental workload from performing all duty required tasks, texting on the phone exceeds the mental workload, resulting in a tragic event. As Kumar et al. (2011) state, these stressors add up. Kumar et al. (2011) discovered in the survey with railway engineers that the highest occupational stressor comes from role overload. Railway engineers often have a long to-do list that they need to follow. Along with long working hours, their attention span, controlled by working memory and the central executive, decreases. 

Another contributing factor to overloaded mental workload is improper information organization. Guastello (2013) demonstrated the importance of information placement relative to the primary task; perception and attention increase for the stimuli if placed at the middle. In the case of railway engineers, their main focus is the front view with the dashboard and occasional traffic signals on the side. When there are speed alert signs on the trackside, with the train going at high speed, it might not be perceived by the rail engineer. Meantime, expertise also plays a role in determining the establishment of cognitive maps, which relates to how information is perceived and organized in the brain. With a more developed cognitive map, operators can better find associations between environmental stimuli and their relationships with the prior knowledge. Retrieval from long-term memory will also place less demand on the working memory because the nodes between pieces of information are strengthened, allowing easier access of knowledge (Brouwers et al., 2017).

Mental Workload’s Impact on Decision Making

When working memory is occupied and overloaded, decision making and problem-solving skills become impaired. Train driving involves all aspects of the cognitive function, including alertness, situational awareness, working memory, memory retrieval, and decision making (Kazemi et al., 2016). All of which take up mental workload. When rail engineers’ already scarce attention and cognitive load is loaded with other tasks such as texting, their decision-making and problem skills decrease, one aspect of problem-solving and decision making involves fault isolation. When the operator lacks extra workload, the central executive cannot allocate attention to working memory or long-term memory for proper retrieval of prior experience (Guastello, 2013). The result is failed fault isolation and no action taken to solve problems or address stimuli alerts. From experience, sound alarms are almost always critical, and failing to respond to such stimuli will only be followed by tragic events.

Potential Solution to Reduce Mental Workload

Other than counteracting factors that negatively impact working memory, such as refraining from unnecessary tasks and improving information organization, understanding the amount of mental workload an operator is experiencing is also crucial in reducing mental workload. There are instantaneous self-assessments that rely on operators’ self-report at time intervals (Maior et al., 2018). However, according to Maior et al. (2018), this method is not only inaccurate at times, but it can also add to the mental workload as another task to perform. If applied to rail engineers, they run the risk of taking their eyes off of the track. Therefore, Maior et al. (2018) discovered that using fNIRS devices to objectively provide real-time feedback to operators regarding their mental workload status reminds the participants to take a breath and re-prioritize their attention without negatively affecting performance. However, implementing fNIRS devices for all operators can be challenging. Therefore, if an automated machine calculates and keeps track of the operators’ decision, assigning a workload to each task, then the system can provide feedback when the operator shows to have made many high-intensity decisions, further reminding operators of the high mental workload they are experiencing. 

References

Brouwers, S., Wiggins, M. W., Griffin, B., Helton, W. S., & O’Hare, D. (2017). The role of cue utilisation in reducing the workload in a train control task. Ergonomics, 60(11), 1500–1515. https://doi.org/10.1080/00140139.2017.1330494

Guastello, S. J. (2013). Human Factors Engineering and Ergonomics: A Systems Approach, Second Edition (2nd ed.). CRC Press.

Kazemi, Z., Mazloumi, A., Nasl Saraji, G., & Barideh, S. (2016). Fatigue and workload in short and long-haul train driving. Work, 54(2), 425–433. https://doi.org/10.3233/wor-162328

Kumar, D., Kharwar, P. S., & Singh, J. V. (2011). Study of occupational stress among railway engine pilots. Indian Journal of Occupational and Environmental Medicine, 15(1), 25. https://doi.org/10.4103/0019-5278.83002

Lauter, D. (2021, January 2). How the Chatsworth train disaster changed rail safety forever. Los Angeles Times. https://www.latimes.com/world-nation/story/2021-01-02/nationwide-positive-train-control-safety-system

Maior, H. A., Wilson, M. L., & Sharples, S. (2018). Workload Alerts—Using Physiological Measures of Mental Workload to Provide Feedback During Tasks. ACM Transactions on Computer-Human Interaction, 25(2), 1–30. https://doi.org/10.1145/3173380