School Bus Safety Act of 2018 This bill requires the Department of Transportation (DOT) to issue rules prescribing or amending motor vehicle safety standards to require school buses with a gross vehicle weight rating of greater than 10,000 pounds to be equipped with a three-point safety belt at each designated seating position. DOT shall also issue rules to require (1) school buses to be equipped with an automatic emergency braking system, an event data recorder, and an electronic stability control system; and (2) at least 30 hours of behind-the-wheel instruction for school bus operators. The Federal Motor Carrier Safety Administration and the Federal Railroad Administration shall publish a final rule entitled "Evaluation of Safety Sensitive Personnel for Moderate-to-Severe Obstructive Sleep Apnea." The National Highway Traffic Safety Administration (NHTSA) shall complete a study of the benefits of requiring school buses to be equipped with a motion-activated detection system that can detect pedestrians located near the exterior of the school bus and alert the bus operator of the pedestrians. The NHTSA must also study the benefits of requiring school buses to have a system that alerts the operator if a passenger is not wearing a three-point safety belt. The bill requires DOT to establish a grant program to assist local educational agencies to purchase school buses equipped with three-point safety belts at each designated seating position and assist them in modifying existing school buses to be equipped with such belts.