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To improve the overall safety and comfort level of highway alignment geometric design scheme, driving simulation experiment is designed and implemented. Firstly, a subjective quantitative evaluation analysis is performed on the amenity, consistency, and comfort of the alignment design. The aggregation area and distribution state of driving speed are analyzed. The consistency of the operating speed consistency of each alignment unit is analyzed on the basis of the unit division of horizontal (H) and vertical (V) alignment. Considering the sensitivity of x-lateral acceleration (Ax) outliers in the driving process, the variation degree of Ax data for each alignment unit is analyzed based on the robust coefficient of variation (RCV), and the units with poor comfort of alignment geometric design are identified. The key range and sequence of optimization adjustment of alignment geometric design elements of alignment are presented by the comprehensive analysis of the combined unit of horizontal and vertical (HV) curves. The results showed that the subjects had higher scores on the amenity and consistency of the alignment design, but the driving comfort was relatively poor affected by the terrain; H2 speed fluctuation is more complex than H1, H1, V2, V3, and V4 units have poor speed coordination sections. Compared with coefficient of variation (CV), RCV is better at characterizing dispersion and stability of Ax data. Adjusting the design index within the alignment unit H2, V3, V4, V5 is the key to improving the overall driving comfort of the route. The RCV of the HV unit is smaller than that of the independent alignment unit. When optimizing the comfort of the design scheme, it is necessary to focus on adjusting the radius and slope of the HV1 unit, considering the combination design of the HV2 and HV3 units, and avoiding the unfavorable combination form containing multiple vertical curves in H2.
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