^^^ Provided you're at an intersection where there is a metal detecting plate in the road and you ride a steel bike, you can lay it down over the patch where the detector is. Upright, it might not be enough metal to be detected. Laid down, it might trigger it. Usually not worth the effort; just look for traffic and cross.
Funny. I ran a light last Sunday night. Crossing a one way street. Stopped. Didn't see any cars coming, so I pedaled through. Just as soon as I get through the intersection, I look over to see a patrol car sitting one car back going the other way. Gave the officer of the law a kind of "uh, sorry" look. He didn't seem to care.