An Investigation of Factors Affecting Driver Alertness

Sussman, E. Donald; Morris, Dominic F. · 1970 · ROSA P / United States. National Highway Safety Bureau

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Summary

This 1970 study, conducted by the Cornell Aeronautical Laboratory for the National Highway Safety Bureau, investigates factors affecting driver alertness during long-duration, low-event driving. The research aims to identify interactions between the vehicle, driver, and road environment that reduce alertness, objectively measure these decrements, and suggest countermeasures. The study combines a literature review with an experimental investigation using a driving simulator to examine the effects of driving time, acoustic noise, and task complexity on driver performance. The experimental design utilized a computer-based driving simulator to ensure safety and control over variables. Forty-eight male subjects with valid licenses and significant driving experience participated in a three-factor design involving two levels of task complexity (manual speed control vs. automatic speed controller) and three levels of acoustic noise (low, moderate, and high, based on measured vehicle spectra). Subjects drove for four hours (240 minutes) while researchers recorded dependent variables including integrated absolute road position error, steering wheel reversals, velocity errors, response latency to stimuli, and physiological metrics such as EEG, EMG, and GSR. A simulated emergency (blowout) was introduced to assess control under stress. The findings indicate that during long-duration, low-event driving, driver alertness degrades linearly over time. Specifically, road position error increased linearly over the four-hour period, while the frequency of steering wheel corrections decreased, suggesting less frequent perceptual sampling or reaction to road position. During the simulated emergency, drivers exhibited greater position error after four hours of driving compared to one hour, with the most severe degradation occurring under high noise conditions. Physiological data showed an increase in alpha bursts in occipital EEG recordings, indicative of reduced alertness. Notably, the study found no performance degradation attributable to the use of a speed controller, contradicting the hypothesis that automatic speed control reduces alertness. The significance of this research lies in its demonstration that alertness declines predictably during monotonous driving, exacerbated by high noise levels during emergencies. The results suggest that road position error and steering correction frequency are valid metrics for assessing alertness decrements. The study recommends further on-road validation and suggests potential countermeasures, such as modifications to road markings or surfaces to mitigate position errors. It also highlights the need for research into pre-attentive processing and selective attention in driving contexts.

Key finding

Drivers showed a linear increase in road position error and a linear decrease in steering corrections over four hours of driving, with emergency control performance degrading significantly after four hours, particularly under high noise conditions.

Methodology

simulator

Sample size: 48

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• vigilance
• drowsiness
• truck driver fatigue
• sleep deprivation
• time on task
• circadian factors

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: physiological data, behavioral performance data
• Theoretical Contribution: theory or model