Abstract: By analyzing the impact of tunnel on the driver′s vision and psychology，changes in speed of vehicle through the tunnel were educed and the length of speed limit in the tunnel was determined. Based on the quantitative analysis of the relationship between variety velocity of pupil area and road safety，the critical speeds of safe driving at the tunnel’s entrance and exit were obtained concerning visual adaptation. The speed limit value of road tunnel is determined，combined with changes of vehicle speed within tunnel speed limit section and the tunnel’s own conditions.

Key words: highway tunnel, speed limit, visual adaptation, safety

摘要： 通过分析隧道对驾驶员视觉、心理的影响，得出车辆通过隧道时车速的变化情况，进而确定了隧道限速段的 长度。利用瞳孔面积变化速度与行车安全关系的定量分析，得出基于视觉适应能力的隧道进出口安全行车的临界 速度，结合车辆在隧道限速段内的速度变化情况及隧道本身条件确定了保证行车安全的隧道限速值。

关键词: 公路隧道, 车速限制, 视觉适应, 安全