Most likely urban myth (although there does seem to be a case that temporary traffic lights used at roadworks may be able to detect emergency vehicles' flashing lights).I don't know if this is any use but might be worth flashing your light at the traffic light, I know some (generally temporary ones) are triggered by light perhaps worth a go just in case it helps?
http://www.snopes.com/autos/law/strobe.asp
https://uk.answers.yahoo.com/question/index?qid=20061007092023AAkLDl8