Rectification of Driver’s Visual Illusion on Continuous Downhill of Urban Underwater Tunnel

To quantitatively study the influence rule of the setting distance of LED rope lights on slope illusion when the gradient gaps are different, a laboratory simulation was completed and analyzed by origin 2017. The results show: (1) the slope illusion is caused by the rotation of visual reference system at the grade change point and its simplicity. The improved scheme can change one-dimensional visual reference to three-dimension. (2) The degree of slope illusion gradually deepens with the increase of gap; (3) Setting LED rope lights at the grade change point can control the driver’s fixation point and avoid the fixation point moving forward, leading to the overestimation of the next slope. The slope illusion can be reduced a bit (4) when the gradient gap is lower than 2.5%, the optimal spacing of LED rope lights is 50 m; when the slope difference is greater than 2.5%, the optimal spacing is 40 m.