为探究在隧道洞口段驾驶员出现视觉滞后对行车安全的影响，在大量调研的基础上建立室内试验模型，开展驾驶人在隧道行车过程中的视觉滞后试验，通过T检验分析数据增量的差异性，提出出现滞后的条件，并分析出现的原因。结果表明： 1）进入隧道，当亮度变化速率S趋于350 cd/m2·s时出现“认知滞后”，增加到约为400 cd/m2·s时出现“调节滞后”； 驶出隧道，当S趋于400 cd/m2·s时出现“认知滞后”，增加到约为500 cd/m2·s时出现“调节滞后”。2）出现“认知滞后”时，对行车安全有一定影响；出现“调节滞后”时，对行车安全的影响更大。3）可采用通过减光设施延长驾驶人视觉适应时间、细化照明分级、无极调光等方法减缓亮度变化速率，来有效抑制滞后现象，提高行车安全。

In order to explore the influence of visual lag occurs to drivers in tunnel portal section on driving safety, a laboratory test model is established based on a great deal of tunnel investigation, and the visual lag test is carried out on driver driving in tunnel. And then, the difference of data increment is analyzed by T tests, and the visual lag conditions and causes are analyzed and proposed. The results show that: (1) When driving into the tunnel, the cognition lag occurs when brightness variation rate reaches 350 cd/m2 · s, and the regulation lag occurs when brightness variation rate reaches about 400 cd/m2 · s; while, when driving out of the tunnel, the cognition lag occurs when brightness variation rate reaches 400 cd/m2 · s, and the regulation lag occurs when brightness variation rate reaches about 500 cd/m2 · s. (2) The cognition lag has a certain influence on driving safety, and the regulation lag has more adverse effects on driving safety. (3) Some methods， i.e. extending driver′s visual adaptation time by using dimming facilities, refining lighting grading and stepless dimming, are suggested to slow down the brightness variation rate, avoid the visual lag phenomenon and improve the driving safety.