Psychological well-being and multimodal predictors of operational safety in heavy-haul railway drivers

Table 1 Descriptive statistics of psychological well-being dimensions and physiological indicator

Variable	mean ± SD1
Mental fatigue	6.81 ± 2.14
Workload	3.09 ± 1.93
Stress level	3.92 ± 2.41
Self-efficacy	7.18 ± 1.89
Emotional state	5.89 ± 1.90
Overall psychological well-being	5.38 ± 0.95
Physiological indicator	4.04 ± 2.20

¹The overall psychological well-being score was calculated as the equally weighted mean of the five psychological dimensions (each weighted at 0.20). Higher scores indicate better psychological functioning after score transformation.

Table 2 Descriptive statistics of cognitive task performance

Task	Trials, n	mean ± SD1
Stroop-accuracy	241	0.801 ± 0.141
Stroop-time (milliseconds)	241	1182 ± 391
Target tracking	196	0.740 ± 0.216
Ligature test (seconds)	181	67.600 ± 20.800
Digit memory	176	6.670 ± 1.830
Ballsport (seconds)	173	1.520 ± 0.810
Balloon	150	10.200 ± 3.490

¹Reaction time for the Stroop task is reported in milliseconds, whereas reaction time for the BallSport task and completion time for the Ligature test are reported in seconds. Accuracy-based indicators are expressed as proportions, and count-based indicators represent raw counts.

Table 3 Joint effects of psychological well-being, individual cognitive tasks, and physiological indicators on the risk of non-full-score operational events (Poisson event-rate models)

Cognitive task1	Drivers (n)	Non-full events	Event rate	Psychological well-being IRR (95%CI)	P value	Cognitive task IRR (95%CI)	P value	physiological IRR (95%CI)	P value
Stroop-accuracy	142	23	0.095	0.88 (0.56-1.38)	0.575	1.06 (0.67-1.84)	0.807	1.19 (0.75-1.77)	0.422
Stroop-time	142	23	0.095	0.89 (0.57-1.40)	0.604	1.01 (0.63-1.60)	0.963	1.20 (0.75-1.80)	0.411
Target tracking	105	20	0.102	0.88 (0.54-1.45)	0.602	1.05 (0.68-1.68)	0.845	0.66 (0.38-1.13)	0.139
Ligature test	100	18	0.099	0.68 (0.40-1.15)	0.160	0.90 (0.56-1.55)	0.688	0.89 (0.47-1.47)	0.679
Digit memory	99	14	0.080	0.90 (0.53-1.48)	0.684	0.78 (0.44-1.40)	0.409	0.26 (0.09-0.68)	0.012
BallSport	94	15	0.087	0.73 (0.38-1.34)	0.324	1.11 (0.67-2.29)	0.731	1.07 (0.60-1.82)	0.797
Balloon	81	9	0.060	0.54 (0.27-1.09)	0.083	1.22 (0.59-3.38)	0.646	1.20 (0.60-2.26)	0.580

¹Each model includes psychological well-being, one cognitive task, and physiological indicator and is fitted on the subsample of drivers who completed the corresponding cognitive task. The outcome is the number of non-full-score events, with the logarithm of total operations used as an offset. Incidence rate ratio < 1 indicates a reduced rate of non-full-score events. All models were estimated using Poisson regression with an offset for the logarithm of total operations. For time-based cognitive measures (e.g., Stroop time, BallSport, Ligature test), scores were reverse-coded so that higher values indicate better performance.

IRR: Incidence rate ratio; CI: Confidence interval.