School bus
In the United States, school buses are yellow while in other countries they may be different. The 3 lines or rub rails on the outside of a school bus in the United States have a purpose for safety in the event of an accident. The bottom line shows where the bus floor is. The middle line shows the bottom of the seat. The top line shows where the top of the seat is as well as the bottom of the window. School buses are also equipped with more than one emergency exit. These could be on the side of the bus, the top, or the back. Each of these is for if the bus rolls one of these sides during an accident. When opened they also will make a loud alarm sound.