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 test was carried out. And the experimental data was analyzed by Origin 2017. The results show that :(1) the slope illusion is caused by the rotation of the visual reference syste at the grade change point and its simplicity. The improved scheme can change the 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 more and avoid the driver's fixation point moving forward which will lead to the overestimation of the next slope. In this way, the slope illusion can be reduced a bit; (4) when the gradient gap is lower than 2.5%, the optimal setting spacing of LED rope lights is 50m; when the slope difference is higher than 2.5%, the optimal setting spacing of LED rope lights is 40m.

CICTP