title: Correlation between Driver Subjective Fatigue and Bus Lateral Position in a Driving Simulator.
abstract: BACKGROUND
  Driver fatigue as a leading cause of death in the transportation industry can impair the driving performance in long-distance driving task. Studies on the links of driver subjective fatigue and the bus lateral position are still an exploratory issue that requires further investigation. This study aimed to determine the correlation between the driver subjective fatigue and the bus lateral position in a driving simulator.
  
  
  METHODS
  This descriptive-analytical research was conducted on 30 professional male bus drivers participated in a two-hour driving session. The driver subjective fatigue was assessed by the Fatigue Visual Analogue Scale (F-VAS) at 10-min intervals. Simultaneously, the performance measures of lane drifting as the mean and standard deviation of the bus lateral position (SDLP) were calculated during the simulated driving task. Descriptive statistics and the Spearman correlation coefficient were used to describe and analyze the data.
  
  
  RESULTS
  Fatigue levels had an increasing trend as the time-on-task of driving increased. Time-on-task of driving had the greatest effect on the fatigue self-evaluation (r = 0.605, p < 0.0001). The results showed a significant correlation between fatigue self-evaluation and bus lateral position (r = 0.567, p < 0.0001).
  
  
  CONCLUSIONS
  As the time of driving increased, driving performance was affected adversely, as shown by the increase in the SDLP. Even so, the effect of individual differences on driving performance should not be overlooked. This work concludes that predicting the state of a driver fatigue based on the group mean data has some complications for any application.
authors.affiliation: Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Iran.
authors.forename: Faramarz
authors.initials: F
authors.lastname: Gharagozlou
authors.affiliation: Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Iran.
authors.forename: Adel
authors.initials: A
authors.lastname: Mazloumi
authors.affiliation: Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Iran.
authors.forename: Gebraeil Nasl
authors.initials: GN
authors.lastname: Saraji
authors.affiliation: Department of Mechanical Engineering, K.N. Toosi University of Technology, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Nahvi
authors.affiliation: Department of Mechanical Engineering, K.N. Toosi University of Technology, Iran.
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Ashouri
authors.affiliation: Department of Mechanical Engineering, K.N. Toosi University of Technology, Iran.
authors.forename: Hamed
authors.initials: H
authors.lastname: Mozaffari
keywords: driver fatigue; driving performance; lane position