(a) A school bus traveling on a highway having 4 or more lanes for vehicular traffic shall stop for the loading or discharging of passengers only on the right side of the highway and when so stopped shall load or discharge only those passengers whose residences are located to the right of the highway. The routes of school buses shall be so arranged that no child shall be required to cross such a 4 or more lane highway to board a school bus or to reach his residence after leaving the bus.
(b) This Section shall not apply when children are escorted by competent persons designated by the school authorities or by law enforcement officers.