It's not common unless you have the 赤信号 at your sight. Sometimes speaker specifies the light color to clarify which traffic light they are talking about when can see several traffic lights nearby. Usually, you're right it should be 信号 not 赤信号. There might be a single traffic light just blinking all the time and the color is only red. If it is the case again to distinguish the light from normal lights which have three lights, the speaker might say 赤信号 and it's not necessarily wrong.

信号機が赤の間は道路を渡るな。 赤信号で通りを渡るのは危険だ。

Thank you, that's very helpful.

I say turn the traffic light. I don't say turn the red light.🚥