A ramp assembly for providing a transition surface between a vehicle floor and an alighting surface is disclosed. The ramp assembly includes a ramp portion that is rotatable between a stowed position and a deployed position. A target operably associated with the ramp portion so that the target reciprocates along a predetermined path when the ramp portion reciprocates between the stowed position and the deployed position. A sensor fitting maintains a fixed orientation relative to a horizontal plane. A sensor is mounted to the sensor fitting such that the sensor senses the target when the ramp portion is in a predetermined position.