Basicly the police say: you should not

"在十字路口中間等綠燈變紅燈時左轉" You should wait "the light is green and no traffic" before entry the intersection and make a left turn. Let's say: if there is continue traffic on the other side from green to yellow until red light, you are turning on the red ? right ? Check the 交通法規. There are must be "do not block ..."