Classification of Driving Workload Affected by Highway Alignment Conditions Based on Classification and Regression Tree Algorithm
Creators: name: Jiangbi Hu
name: Ronghua Wang
Publisher: name: Taylor & Francis
Year: 2017
Subjects: subject: Medicine
subject: Pharmacology
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: Sociology
subject: FOS: Sociology
subject: FOS: Sociology
subject: 80699 Information Systems not elsewhere classified
subject: FOS: Computer and information sciences
subject: FOS: Computer and information sciences
subject: Science Policy

description: <b>Objective:</b> Guaranteeing a safe and comfortable driving workload can contribute to reducing traffic injuries. In order to provide safe and comfortable threshold values, this study attempted to classify driving workload from the aspects of human factors mainly affected by highway geometric conditions, and to determine the thresholds of different workload classifications. This paper stated a hypothesis that the values of driver workload change within a certain range. <b>Methods:</b> Driving workload scales were stated based on a comprehensive literature review. Through comparative analysis of different psychophysiological measures, heart rate variability (HRV) was chosen as the representative measure for quantifying driving workload by field experiments. 72 participants (36 car drivers and 36 large truck drivers) and six highways with different geometric designs were selected to conduct field experiments. Wearable wireless dynamic multi-parameter physiological detector (KF-2) was employed to detect physiological data that were simultaneously correlated to the speed changes recorded by a GPS (testing time, driving speeds, running track, and distance). Through performing statistical analyses, including the distribution of HRV during the flat straight segments and P-P plots of modified HRV, a driving workload calculation model was proposed. Integrating driving workload scales with values, the threshold of each scale of driving workload was determined by Classification and Regression Trees (CART) algorithm. <b>Results:</b> The driving workload calculation model was suitable for driving speeds in the range of 40 km/h to 120 km/h. The experimental data of 72 participants revealed that driving workload had a significant effect on modified HRV, revealing a change of driving speed. When the driving speed was between 100 km/h and 120 km/h, drivers showed an apparent increase in the corresponding modified HRV. The threshold value of the normal driving workload K was between -0.0011 and 0.056 for a car driver, and between -0.00086 and 0.067 for a truck driver. <b>Conclusion:</b> Heart rate variability was a direct and effective index for measuring driving workload despite being affected by multiple highway alignment elements. The driving workload model and the thresholds of driving workload classifications can be used to evaluate the quality of highway geometric design. A higher quality of highway geometric design could keep driving workload within a safer and more comfortable range. This study provided insight into reducing traffic injuries from the perspective of disciplinary integration of highway engineering and human factor engineering.