In　order　to　obtain　the　minimum　illuminance　of　the　active　＂lighted＂delineators　satisfying　the　demand　that　driver　can　recognize　the　tunnel　alignments　and　the　boundaries　of　the　walkway　for　inspection　and　maintenance　in　a　highway　tunnel,　the　recognition　tests　were　designed.　The　white　and　yellow　LED　delineators　frequently　used　with　different　levels　of　illuminance　were　selected.　The　lighting　environment　in　a　highway　tunnel　with　three　kinds　of　color　temperature,　six　levels　of　luminance　was　settled.20　tested　car　drivers　were　selected　to　conduct　the　recognition　tests.　The　correlation　models　between　the　luminance　of　tunnel　lighting　environment　and　the　illuminance　of　the　LED　delineators　were　established　under　different　kinds　of　color　temperatures　of　tunnel　lighting　environment.　The　results　show　that　the　minimum　illuminance　of　the　LED　delineators　increases　with　the　luminance　of　tunnel　lighting　environment.　The　minimum　thresholds　range　from　539~147,021　lx　and　3,719~41,308　lx　for　yellow　and　white　LED　delineators　respectively.　©　2020　ASCE.