Nice sentence but I honestly can't see its relation to the topic traffic
Indeed how out of blue! lol
He scratches his back while waiting for his bus. =버스를 기다리는 동안 그는 등을 긁어요. "
Things that happen just before a traffic accident. 기사가 등을 긁어요. 나중에 그는 죽었어요.
도로를 건너면서 등을 긁으려고 멈추면서 차에 치였습니다. 보행자가 죽었습니다.
Stopping to scratch his back while crossing the street, he was hit by a car. The pedestrian died.
I'm guessing it's to introduce words used elsewhere in the topic in different contexts so it helps you learn them more easily.
등 --> 신호등, 가로등 possibly :)