Psychological work characteristics, psychological workload and associated psychological and cognitive requirements of train drivers

High-speed train drivers' human error under fatigue and stress: the role of situation awareness and individual differences

Fatigue and stress are critical variables that impair railway train drivers' safety performance, and individual differences may influence these effects. This study investigates how fatigue and stress affect high-speed train drivers' human error and the role of individual differences. We hypothesised that situation awareness (SA) mediates the effects of fatigue and stress on human error, and individual differences (age and work experience) moderate these effects. We surveyed 1,391 male drivers from eight Chinese railway bureaus and used PROCESS Macro for data analysis. The results revealed that fatigue and stress increased human error, directly and indirectly through SA. Age and work experience moderated the effect of fatigue and stress on SA, respectively. Older drivers had better SA under high fatigue, while more experienced drivers had better SA under high stress. These findings can inform more tailored safety management strategies to lower human error and enhance the safety of high-speed train operations.

Correlation of Work Fatigue and Mental Workload in Train Drivers: A Cross-sectional Study

BACKGROUND

Evidence suggests that train drivers experience a high level of fatigue and mental workload. The present study aimed to assess overall, physical, and mental fatigue levels and their correlations with the mental workload in the metro train operation. Study Design: A cross-sectional study.

METHODS

This study was conducted on all 1194 train drivers in the Tehran Metro. The train drivers completed the Samn-Perelli Fatigue Scale and the Fatigue Assessment Scales at the beginning and end of the shift. In addition, they completed the National Aeronautics and Space Administration Task Load Index in the middle and at the end of the shift. Correlation and regression analyses were performed on the data to test the study hypothesis.

RESULTS

Overall, physical, and mental fatigue levels increased significantly at the end of the shift compared to the onset of the shift (P<0.001). The mental workload and related dimensions were significantly increased at the end of the shift compared to the middle of the shift (P<0.001). Mental demand was the most important workload problem among the train drivers. The highest correlation was found between overall workload and time pressure (R=0.68, P<0.001).

CONCLUSION

The mental workload had a significant correlation with work fatigue in the train drivers. Control measures should be focused on the mental workload and related dimensions, especially mental demand and time pressure.

Types, Risk Factors, Consequences, and Detection Methods of Train Driver Fatigue and Distraction

Train drivers' inattention, including fatigue and distraction, impairs their ability to drive and is the major risk factor for human-caused train accidents. Many experts have undertaken numerous studies on train driver exhaustion and distraction, but a systematic study is still missing. Through a systematic review, this work aims to outline the types, risk factors, consequences, and detection methods of train driver fatigue and distraction. The effects of central nervous fatigue and cognitive distraction in train drivers during driving are caused by rest and sleep schedules, workload, automation levels, and mobile phones. Furthermore, train drivers' fatigue and distraction can cause loss of concentration and slow reaction, resulting in dangerous driving behaviour such as speeding and SPAD. Researchers have combined subjective reporting, physiological parameters, and physical factors to construct detection algorithms with good results to detect train driver fatigue and distraction. This review offers recommendations for researchers looking into train driver fatigue and distraction. And it can also make valuable recommendations for future studies about railway traffic safety.

Measuring Auditory Fitness in Locomotive Engineers: Development and Validation of a Signal Detection Test

OBJECTIVES

To perform their job safely and effectively, locomotive engineers are required to detect auditory warning signals in the noisy work setting of a train cabin. Based on audio recordings of Dutch train cabins, we have developed a task and job-specific test for assessing the engineer's ability to detect the two acoustic warning signals for the Dutch situation. The aim of this study was to evaluate the reliability, agreement, and construct validity of this test.

DESIGN

Two experiments were performed. In the first experiment, reliability and agreement of the signal detection test were assessed. Normally hearing individuals (N = 12) completed a signal detection test twice in 12 driving conditions. In the second experiment, construct validity was assessed. We retrospectively identified locomotive engineers, suspected of being hearing impaired, who were referred to the Amsterdam UMC for an auditory fitness for job assessment. All included engineers (N = 83) performed the signal detection test in four driving conditions, underwent tone audiometry and two speech perception in noise tests, and rated the effort and concentration it takes to detect the auditory signals. Seven a priori formulated hypotheses were tested.

RESULTS

In the first experiment, sufficient reliability and agreement were found in nine driving conditions (ICC = 0.54-0.81; standard error of measurement = 1.15-1.92), poor reliability in two driving conditions (ICC < 0.50), and poor agreement in one driving condition (standard error of measurement = 2.67 dBA). In the second experiment, the results of the signal detection test correlated moderately with the pure-tone thresholds, speech reception threshold in fluctuating noise, and engineer's subjective rating of effort and concentration, but not with the speech reception threshold in continuous noise. According to the hypotheses, poorer test scores were obtained by hearing aid users compared with nonhearing aid users.

CONCLUSIONS

The signal detection test has sufficient reliability and agreement in all but three driving conditions. This study provides evidence supporting the construct validity of the signal detection test in locomotive engineers. The moderate associations with conventional hearing tests show that the conventional hearing tests did not cover the whole construct measured with the signal detection test. The results, therefore, underpin the importance of evaluating the ability to detect auditory warning signals separately from other hearing-critical job tasks.

Detectability of auditory warning signals in the ambient noise of Dutch train cabins

Locomotive engineers need to detect auditory warning signals for safe and effective job performance. We measured the levels and spectra of the warning signals and noises present in Dutch train cabins to evaluate the effectiveness of these signals. Audio-recordings were made in six train types during normal operation. Signal detectability was estimated using the Detectsound software and compared against ISO 7731. Signal detectability was also measured in six normally-hearing individuals in a laboratory setting. Signal levels ranged between 68 and 84 dBA. Noise levels ranged between 53 and 77 dBA. The acoustical requirements for signal detectability were not met in multiple driving conditions, especially at higher speed. Sufficient signal-to-noise ratio's were achieved in the laboratory measurements, but difficulties can be expected in unfavourable driving situations or when the engineer suffers from hearing loss. Acoustical, environmental, or work modifications might be required to prevent situations with insufficient audibility in hearing-impaired engineers. Practitioner summary: The audibility of the warning signals in Dutch trains was evaluated by comparing signal and noise spectra. The results showed that sufficient audibility is not always guaranteed. Under laboratory conditions, normally-hearing individuals could compensate for the suboptimal acoustic circumstances, but acoustical, environmental, or work modifications might be required to prevent situations with insufficient audibility in hearing-impaired engineers.

Fatigue in the Indonesian rail industry: A study examining passenger train drivers

OBJECTIVE

The railway industry in Indonesia has grown substantially in the past five years, with greater network and tracks length that will double in 2030. There has been a growing concern, however, that fatigue among front-line personnel have not been addressed satisfactorily. This study aimed at evaluating the degree of fatigue among passenger train drivers and suggested practical recommendations to the Indonesian Railway Company.

METHOD

A total of 32 train drivers (driving for about 4 h during the morning or afternoon shifts) agreed to participate in the study. Subjective and objective measures of fatigue (and sleepiness) were obtained prior to, during, and immediately following the end of a duty. Fatigue and driving performance were also determined based on (off-line) analysis of continuous video recordings of the drivers performing the duty.

RESULTS

Fatigue generally increased as a function of time and, for some, 2 h of driving was sufficient in inducing substantial level of fatigue increase. Unlike the morning shift, the afternoon shift was characterized with increased undue fatigue and unacceptable level of performance decrements.

CONCLUSION

In general, fatigue was not found among train drivers working the morning shift. For these drivers, however, there were a couple of individuals with excessive levels of fatigue. The effects of fatigue were more apparent for the afternoon shift. This is possibly due to the degraded sleep quality as a result of split rest periods obtained prior to the duty. It is suggested in this study that the company pay a much closer attention to the work-sleep schedules, and to improve sleep quality by redesigning better sleeping arrangements.

The association between demographic characteristics, personality, and mental health of bus drivers in China: A structural equation model

BACKGROUND

The psychological status of drivers is related to adverse driving behaviors. Although there are several studies on the mental health and traffic accidents among bus drivers, related studies on the association between mental health and individual characteristics are scarce.

METHODS

Our report is on a cross-sectional study of bus drivers that took place between October 2014 and May 2016. A total of 596 bus drivers who worked for transportation companies and underwent occupational physical examinations at The Guangxi Zhuang Autonomous Region workers' Hospital during the study period were included. Demographic characteristics were collected by a self-designed demographic questionnaire. The Eysenck Personality Questionnaire (EPQ) and the Symptom Checklist 90-Revised (SCL-90-R) were used to evaluate the personality and mental health of bus drivers, and the results of the scales were compared with Chinese norms. The structural equation model was used to analyze the correlation among demographic characteristics, personality characteristics, and mental health.

RESULTS

Except for the lie dimension, the average scores of the driver's personality dimension were higher than the Chinese norm, and the means of somatization and phobia scores of bus drivers were also higher; obsessions-compulsions, interpersonal sensitivity, and depression scores were lower than those for the Chinese norms. The structural equations modeling revealed that the total effects coefficient of demographic characteristics on mental health was 0.68, and that of personality was 0.60. There were direct influences between demographic characteristics and personality characteristics, demographic characteristics and mental health, and personality characteristics and mental health; the standardized path coefficients were 0.60, 0.50, and 0.30, respectively. Smoking, drinking, and neuroticism were the main factors affecting the mental health of bus drivers; and the standardized path coefficients were 0.56, 0.54, and 0.90 respectively.

CONCLUSIONS

In this study, bus drivers were significantly more extroverted, psychotic, and neurotic than the general population; and they were more likely to suffer from somatization and phobia. The mental health of bus drivers was associated with some demographic and personality characteristics in the study. These findings provide a theoretical basis for the selection of bus drivers and intervention measures for drivers with high-risk driving tendencies, which is conducive to better guide road traffic safety construction and reduce the occurrence of road traffic injuries.

Going solo: Hierarchical task analysis of the second driver in "two-up" (multi-person) freight rail operations

While many countries have dual-driver ("two-up") modes in freight rail, driver shortage creates increasing pressure to move to single-driver operations. While this change has implications for workload and safety, the roles of the primary and second drivers have not been systematically mapped. This mapping is the focus of this paper, which presents a hierarchical task analysis (HTA) from a multi-methods study (n = 40). Results indicated that transitioning from two-up to single driver operations will result in substantial changes in physical and cognitive workload for the remaining driver. These changes go much further than the simple loss of a crew-mate to double-check or verify actions and cues. This HTA can form the basis of an evidence-based safety case for the change from two-up to single-driver operations, as well as a platform for considering mechanisms to maintain safety and productivity for the now solo train driver.

It Comes With the Job: Work Organizational, Job Design, and Self-Regulatory Barriers to Improving the Health Status of Train Drivers

OBJECTIVE

This study aimed to examine the impacts of key barriers to improving the occupational health status of Australian train drivers.

METHODS

From May to June, 2015, five semi-structured qualitative focus groups were conducted with 29 train drivers from South Australian, Victorian, and New South Wales-based rail organizations in Australia.

RESULTS

Occupational health was impeded by multiple barriers regarding sleep (patterns/fatigue), diet (planning/context), mental health (occupational stress), rostering (low autonomy), sedentary time, low fitness motivation, and family/social life conflicts. Work organizational barriers included communication issues, low organizational support, and existing social norms. Job design barriers included rostering, fatigue, stimulant reliance, and family/social life imbalances. Self-regulatory barriers included dietary and exercise patterns habits and patterns.

CONCLUSIONS

Occupational health interventions for Australian train drivers must address work organizational, job design, and self-regulatory barriers to healthier lifestyle behaviors.

Quantitative modelling in cognitive ergonomics: predicting signals passed at danger

This paper shows how to combine field observations, experimental data and mathematical modelling to produce quantitative explanations and predictions of complex events in human-machine interaction. As an example, we consider a major railway accident. In 1999, a commuter train passed a red signal near Ladbroke Grove, UK, into the path of an express. We use the Public Inquiry Report, 'black box' data, and accident and engineering reports to construct a case history of the accident. We show how to combine field data with mathematical modelling to estimate the probability that the driver observed and identified the state of the signals, and checked their status. Our methodology can explain the SPAD ('Signal Passed At Danger'), generate recommendations about signal design and placement and provide quantitative guidance for the design of safer railway systems' speed limits and the location of signals. Practitioner Summary: Detailed ergonomic analysis of railway signals and rail infrastructure reveals problems of signal identification at this location. A record of driver eye movements measures attention, from which a quantitative model for out signal placement and permitted speeds can be derived. The paper is an example of how to combine field data, basic research and mathematical modelling to solve ergonomic design problems.

Investigating the formal countermeasures and informal strategies used to mitigate SPAD risk in train driving

Various countermeasures are used to mitigate signal passed at danger (SPAD) events on railways, yet they continue. While risk factors that destabilise cognitive processes have been identified, less has been published on the relationship between these factors and the informal strategies that drivers themselves adopt to reduce individual SPAD risk. This study aimed to address this gap and used a participative approach to collect and thematically analyse data from 28 drivers across eight rail organisations in Australia and New Zealand. The results showed not all formal countermeasures were considered effective, and identified several informal strategies. These aimed to reduce task disruption, service distortion and maintain connectedness to signals. While some evidenced redundancies in the task and cab, others did not reduce baseline risk. This paper explores the relationship between the established risks and identified strategies towards evaluating the utility of formal and informal mitigations. The research has application to the investigation of collision risk in all transport domains. Practitioner Summary: A participative approach was used to investigate SPAD mitigation techniques in train driving, and to explore risk-strategy relationship dynamics. Several informal strategies designed to reduce task disruption, service distortion and maintain signal connectedness were identified. While some evidenced redundancies in the task and cab, others did not reduce baseline risk.