Study On Driving Fatigue Formation Mechanism

There exists large potential safety hazard when drivers work under the state of fatigue. So far, driver fatigue accidents occur frequently despite many countermeasures are taken, which are seldom effective. The paper believes that the insufficient study of the meaning and mechanism of driver fatigue is the main reason for the lower effectiveness of countermeasures. In order to solve the problem of driver fatigue effectively, from the road and traffic engineering point of view, the paper focuses on the formation mechanism of driving fatigue caused by road, traffic and environmental conditions. It is included in the paper that the formation model, the measurement indicators, the threshold, and the countermeasures of driving fatigue.Based on the study of arousal level theories related to driving fatigue in physiology and psychology, with relevant researches as reference, the paper brings in the concept of arousal level, makes analysis and research on the generation process of driving fatigue, and comes up with a series of reasoning. Experiments were taken to study the effect of the elements of road and traffic environment on arousal level, and the inferences were verified and improved. On this basis, driving fatigue formation model was established, with arousal level as the evaluation criteria. Through the model, the generation time of driving fatigue was determined according to the changing characteristics of arousal level. And the formation process of the two most common driving fatigue that the long time and the short time driving fatigue were explained.According to the analysis on the driving process and the changing characteristics of the arousal level while driving fatigue, two driving fatigue measurement methods, that EEG and ECG were selected, and the coefficient of variation indicators of EEG and ECG were put forward. Indoor experiments were made in the driving simulator system, with brake reaction time as the independent indicator, and the reliability of indicators was studied. Based on the consideration of the reliability and availability of the indicators, ECG coefficient of variation indicator, RRCV, was finally recommended as the valid measurement indicator of driving fatigue.In order to gain an evaluation criterion of driving fatigue applicable for all the drivers, the paper first changed RRCV to the indicator of driving fatigue degree. On the basis of research on common used threshold method, a new threshold calculation method was put forward using subjective and objective data comprehensively. With this method, data collected from the field test were calculated, and the threshold was gained which can be used to determine the generation time of driving fatigue.With the application of the indicator of driving fatigue degree and the threshold, according to the impact of road and traffic environment on driving fatigue, using the field test method, some recommendations about the regulations of the driving time, the design of roadside landscape and road alignment to prevent driving fatigue were proposed.The research results can be used as reference for establishment of relevant laws and regulations, guidance for the design and management of roads and related facilities, help for the driver fatigue detection system design, and support for driver education and management. Thus the occurrence of driving fatigue can be reduced or mitigated, and traffic safety can be improved.