A drive device for embarkation and disembarkation devices of public transportation vehicles includes a drive unit arranged within and for driving a rotary column. The drive unit rotates the rotary column about the rotary column longitudinal axis Z-Z during opening and closing processes of the embarkation and disembarkation devices. The drive device is supported on the vehicle. The drive unit includes a drive motor, a non-self-locking reduction gear, and a controllable blocking component with which a rotation of the rotary column can be blocked. The drive device further includes a sensor for detecting the magnitude of an external force, wherein the force acts on the drive device. The drive device further includes an element for analyzing signals of the sensor and for triggering the blocking effect of the blocking component when an external force measured by the sensor exceeds a threshold.