This is sung to the same tune as "Twinkle, Twinkle, Little Star". Every night, after being tucked into bed I allow my kids to each pick one song to sing. When I sing this to my kids, I always use hand motions and vary my speed with the different traffic light colors. Red is always abrupt and green is always done fast. When I get to what yellow means, I say, "Yellow means to take it sloooowwww". They always giggle at that, I like it.

Twinkle, twinkle traffic light,
Standing on the corner bright.
Red means stop,
Green means go,
Yellow means to take it slow.
Twinkle, twinkle, traffic light,
Standing on the corner bright.

arrogantsob says re: Twinkle, Twinkle, Traffic Light: When I heard this song, the 5th line was different: "Yellow means wait, even if you're late."