Abstract
Changes in lateral clearance are prone to drastic changes in the driving environment at the entrance and exit of the tunnel, which can cause a driver to become psychologically stressed and deviate from the center of a lane, thus creating a greater security risk. However, most of the existing regulations and studies only focus on the horizontal and vertical alignment of the tunnel entrances and exits, and there are few studies on the influence of lateral clearance on driving behavior. This study hired 15 random subjects to conduct real vehicle tests in eight tunnels on expressways with 3 design speeds by using a CAN-OBD analyzer and steering wheel angle meter. First, in five lateral clearance variation schemes, different speed characteristic indicators and steering wheel angles were selected as the indicators of driving behavior. Second, the interactive influence of the design speed, lateral clearance, operating speed, steering wheel angle, and other indicators were analyzed. Finally, paired t-test analysis and Wilcoxon and Friedman nonparametric tests were used to compare the differences in various indicators among different lateral clearance schemes. The results showed that when the left lateral clearance is 1.5 meters, the operating speed is increased by 3.9%, while the standard deviation of speed is small, and the driving performance is higher. When the right lateral clearance is 1.75 and 2.00 meters, the operating speed is not much different. However, the latter’s speed standard deviation is smaller. By contrast, when the right lateral clearance is up to 2.25 m, the operating speed increases by 3.7%. However, the speed standard deviation also increases. Different lateral clearances have little effect on the steering wheel angle. The operating speed on the right side is higher and more stable when the design speed is 100 km/h. This study provides scientific suggestions for the setting of the lateral clearance of the tunnels.
Highlights
Highway tunnels are important structures on mountain roads, and they account for an increasing proportion of the total mileage of traveled routes
The driving behavior and the changing law of vehicle operation under different lateral clearances of tunnels are studied. e field tests of five lateral clearance schemes in eight tunnels are carried out for data collection. e operating speed, speed standard deviation, and steering wheel angle which can reflect the driving stability and the lane keeping control ability of drivers are taken as the characterizing parameters of driving performance. ere is a multitude of factors that may play a role, and different combinations can yield different results. is notion is supported by the interaction influence analysis of the indicators and lateral clearances
In the left lateral clearance environment, compared to the lateral clearance with 1.25 m, the operating speed of the lateral clearance with 1.50 m is increased by 3.9%, and the speed standard deviation is relatively small. us, the design of the left lateral clearance with 1.50 m has improved the driver performance. is could be a hint that such wider lateral clearance is beneficial to ensure that drivers maintain higher speed and better safety
Summary
Highway tunnels are important structures on mountain roads, and they account for an increasing proportion of the total mileage of traveled routes. 80% of the accidents in a tunnel section are caused by the violent transitions of the alignment, lighting, antiskid, and traffic safety facilities inside and outside the tunnel. The Specification for Design of Highway Tunnels (JTG D70/22014) only stipulates that the horizontal and vertical alignment of the tunnel entrance and exit within 3 seconds of the travel range should be as consistent as possible, and there are few quantitative cross-sectional index requirements [4]. When vehicles approach the entrance and exit the tunnel, the width of Journal of Advanced Transportation the cross section inside and outside the tunnel will affect the driving psychology and driving behavior. Lanes that are too wide will lead to frequent overtaking, and it is not conducive to driving safety
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