Monotony of road environment and driver fatigue: a simulator study Pierre Thiffault, Jacques Bergeron 18 May 2001 David Shen Kevin Rahardja IE April 2007

Purpose Evaluate the impact of the monotony of road environment on driver fatigue by altering alertness and vigilance.

Background Support Dinges (1995) : Vigilance decrement is the most robust effect of fatigue and sleepiness. Nelson (1997): Highway design, and especially the lack of stimulation, can play a role in a fatigue-related accidents. Education should be oriented towards teaching how conditions in the environment can influence the development of fatigue-related symptoms.

Theoretical Basis / Hypothesis General causes of fatigue and drowsy driving: Endogenous factors: Smiley (1998) identified long hours (time-on-task effect), time of day, and sleep-related problems, not only as major contributors to fatigue, but also as potential corrective measures in preventing fatigue-related road accidents. Time-on-task effect could produce fatigues and cause degradation in driving performance during the very early stages of a driving or vigilance task. Summala and Mikkola (1994): the time-of-day effect – sleep related accidents. More accidents between 2:00 – 6:00 am than 2:00 – 6:00 pm

Theoretical Basis / Hypothesis General causes of fatigue and drowsy driving: Exogenous factors: Characteristics of road geometry and roadside environment can affect driving performance by affecting arousal, alertness and information processing, e.g. monotonous road environment with low traffic density can produce fluctuations of arousal that decrease alertness and vigilance. Nelson (1997): Highway design, and especially the lack of stimulation, can play a role in a fatigue- related accidents.

Theoretical Basis / Hypothesis The impact of monotony Almost every study examining driver fatigue and drowsy driving suggests that it is more frequent on monotonous road environments such as highways. Arousal Theory (Davies and Parasuraman, 1982): performance is poor when arousal is either weak or very strong. Habituation Theory (Mackworth, 1969): the repetitive nature of sensory stimulation under monotonous conditions would habituate the neural response and thereby explain the progressive decline in detection rate found over time during vigilance tasks.

Theoretical Basis / Hypothesis The impact of monotony: Highway hypnosis: “the tendency of the automobile driver to become drowsy and to fall asleep during monotonous, uneventful highway driving” (Thackray, 1970) Driving Without Attention Mode (DWAM): occurs when individuals have difficulties remembering the experiential details that occur during long driving periods. Under monotonous road conditions, attention and control would shift from external to internal events. Since the driver becomes less aware of what is happening in the environment, his driving performance tends to rely on an internal schema of the driving activity (Kerr, 1991). Ecological perspective: the nature of the driver/environment relationship has a fundamental impact on alertness and vigilance, and that task induced, or exogenous factors, have to be considered in conjunction with endogenous factors in a general analysis of this phenomenon (Nelson, 1997).

Theoretical Basis / Hypothesis The effect of ruptures of monotony on drivers’ fatigue: Various studies suggest that road monotony has a negative effect on alertness and vigilance and that ruptures of monotony could help ward off driver fatigue, at least temporarily.

Practical Contribution Provides useful data regarding the utility of environmental countermeasures against driving fatigue, e.g. highway design Provides insight into other fatigue- related problems both physiologically and psychophysiologically.

Theoretical Contribution Provides a systematical evaluation and results on the effect of the landscape monotony on driver fatigue and vigilance

Methodologies 56 male university students, paid, mean age 24 years. Used a fixed-based driving simulator with a potentiometer to record steering wheel movements ( SWM). All subjects tested during post-lunch dip period (1:20pm – 2:10 pm) then 15 min break, then again at 2:25pm – 3:05pm Before, in between and after tests, they were given a subjective alertness test. Order was randomly counterbalanced across subjects

Methodologies Cont… Driving task was same for the two 40- min periods, only road environment differed. Told to keep car as straight as possible. Road A scenery : trees Road B scenery : trees, houses, farms, pedestrians, signs, bridge, overpasses.

Variables studied : standard deviation of lateral position, mean amplitude of SWM, frequency of larger SWM, standard deviation of SWM. Speed measures were computed but showed no significant variability Alertness was recorded on a 5 point Likert scale at the beginning and end of the driving period Statistical Analysis / Assumptions

Results ANOVA and Trend Analysis Conducted Evaluate 1.) effect of time 2.) road environment repetitive stimuli : Road A variable stimuli : Road B

Time on Task :Road A ( boring road ) had an increase in the frequency of large steering wheel movements.

Subjects made large steering wheel movements more often when driving on road A

Conclusions Amplitude and frequency of SWM tends to increase with experienced fatigue during driving : Road A had more frequent and pronounced SWM. Time on task results indicated that as the driving period got longer, more SWM were recorded. Impact of fatigue is robust and appears quite early, with a peak between min of driving. Correspondence between SDSWM and amplitude measures reinforces the fatigue-related phenomenon of monotony.

Future Work / Research Research into “wake-up” measures aimed at detecting driver fatigue. Problem of exogenous causes of driver fatigue. Research into more pronounced interruptions of monotony than those used in this study ( size, color, intensity, shape )