Wheeled mobility devices that are not secured properly on large transit vehicles pose risks to all passengers. The purpose of this study was to increase the understanding of the effects of horizontal and vertical curves, speed, and driver behavior on the safety and security of people using wheeled mobility devices in rear-facing passive containment systems on large transit buses. Testing included the use of manual wheelchairs and lightweight scooters on an articulated low-floor transit bus. The project conclusions were derived from data produced by accelerometers placed on the bus as well as visual observations of wheeled mobility device movement. The data showed a clear difference in the amount of movement of the wheeled mobility devices and the comfort of the seated passenger when the bus traveled on a combination of horizontal and vertical curves at different driving speeds.