公路隧道入口照明的连续性调光，是确保在安全前提下实现按需照明的关键。针对公路隧道加强照明调光方式中频繁出现亮度跳变和亮度过低的问题，利用杭州彩虹快速路特长隧道LED智能化精细调光照明系统记录下的洞外亮度变化曲线，换算出理论调光曲线，并与实际调光曲线进行图形化对比研究，揭示导致亮度频繁跳变和亮度低于标准要求的形成原因，提出通过增加调光亮度等级和减小调光间隔时间进行改善。得出如下结论： 1）调光的亮度等级越高，调光的间隔时间越短，从而使隧道入口段出现亮度跳变的幅度越小，行车越安全； 2） 照明调光系统的精细化程度和调光操作的间隔时间，是体现系统安全性的重要指标。

The continuous dimming of the illumination at the entrance section of the highway tunnel is critical to realize illumination on demand under the premise of safety. Regarding the problems of brightness jump and brightness insufficiency frequently appearing during the dimming of highway tunnel enhanced illumination, this paper uses the adaptation luminance change profile recorded by the LED intelligent fine dimming illumination system of Caihong expressway extralong tunnel in Hangzhou, to fit into a theoretical dimming profile, and make graphic comparable research with the real dimming profile. It reveals the reasons causing brightness frequently jump and brightness lower than the standard requirement, and proposes methods to improve dimming safety, and draw the following conclusions: 1) With higher level of dimming brightness and shorter interval, the amplitude of brightness jump at the tunnel entrance section will be smaller and the traffic is more safe; 2) The fineness of illumination dimming system and interval of dimming operation are important indexes of system safety.