## 6 Conclusions  
This study obtained driving data including vehicle speed, lateral acceleration, and longitudinal acceleration through real vehicle experiments, and explored the significance of the relationship between acceleration and curve types, radius, and angles through data analysis. It evaluated the risk and distribution characteristics of drivers' driving behaviors on curves based on the acceleration driving risk model, and conducted a significant test on the differences in driving risk points. Finally, it discussed the correlation between curve radius, angle, vehicle lateral acceleration, entering curve deceleration, and exiting curve acceleration. The main conclusions are as follows:  
1. Significant differences exist in lateral acceleration and longitudinal acceleration under different radius ranges when driving at curves in urban underground roads. There is a significant difference in the lateral acceleration between the independent curves and the S-curves, and the longitudinal acceleration does not exist. There are significant differences between some groups in the entering curve deceleration and exiting curve acceleration for curves with different radius ranges and different angle ranges. 2. The number of driving risk points per unit length (m) under different curve types does not show significant differences. The number of driving risk points per unit length (m) of the extreme small radius curve and the general small radius curve is significantly larger than that of the ordinary radius curve. 3. The number of danger points at curves increases initially with mileage, then stabilizes with fluctuations for a distance, and finally decreases. The road sections with the highest level of danger points are mainly concentrated within the circular curve sections of the curves, especially in the latter half of the circular curve section in the direction of travel. 4. The lateral acceleration of vehicles at curves in urban underground roads shows the following relationships with curve radius and angle: when the curve radius is less than 80 m, the lateral acceleration decreases initially with increasing radius and then increases; when the radius is greater than 80 m, it initially increases and then decreases. When the curve angle is less than 50\({}^{\circ}\), the lateral acceleration increases initially with the angle and then decreases as the angle increases; when the angle is greater than 50\({}^{\circ}\), it decreases initially and then increases. The entering curve deceleration and exiting curve acceleration of vehicles at curves in urban underground roads both show a trend of initially decreasing and then increasing with increasing curve radius and angle. Additionally, R > 60 m and \(\alpha\) < 70\({}^{\circ}\) are the recommended value ranges for small radius curves. In some situations, drivers can enter urban underground roads in a fatigued state, and the duration of driving and fatigue will to some extent influence a driver's choice of speed, thereby affecting acceleration [51]. However, in this study, the subjects were in good condition at the start of the experiment, it does not account for the initial impact of driving experience, curve direction, or psychophysiological factors. Therefore, future research should incorporate additional parameters such as driver eye movements and electrocardiograms to provide a more comprehensive assessment of driver behavior from a psychophysiological perspective. Furthermore, special attention should be given to the construction of measurement systems to ensure the construction of a correct mathematical apparatus. Meanwhile, experiments could be expanded to include different underground roadways, varying traffic densities, illuminance levels, and vehicle models as variables to validate and extend the conclusions. Finally, comparative analyses with aboveground roads could be conducted to further enrich the study's insights. Z.Z. : methodology, project administration, writing--review and editing. Y.X. : investigation, visualization, writing--original draft. Z.W.