Facility comprising a movable part which is movable on a movement surface of the facility, wherein a sensor assembly is fastened to the movable part, in particular to the underside of the movable part, wherein the sensor assembly comprises a housing, in particular a plastic housing, wherein a first sensor, which operates in accordance with a first physical operating principle, and a second sensor, which operates in accordance with a second physical operating principle, are arranged within the housing, wherein the first operating principle is different than the second operating principle, wherein the sensor signal of the first sensor, in particular the sensor signals of both sensors, can be fed to a first computing unit of an evaluation electronics arranged within the housing, wherein the sensor signal of the second sensor, in particular the sensor signals of both sensors, can be fed to a second computing unit of the evaluation electronics, wherein the first computing unit is designed to determine a first value of the speed of the movable part from the sensor signal of the first sensor, wherein the second computing unit is designed to determine a second value of the speed of the movable part from the sensor signal of the second sensor and to monitor it for exceeding a permissible extent of deviation from the first value, wherein the first sensor is a radar sensor and the second sensor is a light sensor, wherein the housing is configured in such a way that the light beams emitted and received by the light sensor can penetrate a transparent region of the housing, and wherein the transparent region of the housing is a portion of the housing and the radar sensor is further away from the transparent portion than from the rest of the housing, which in particular is opaque to light. wherein a sensor assembly is fastened to the movable part, in particular to the underside of the movable part, wherein the sensor assembly comprises a housing, in particular a plastic housing, wherein a first sensor, which operates in accordance with a first physical operating principle, and a second sensor, which operates in accordance with a second physical operating principle, are arranged within the housing, wherein the first operating principle is different than the second operating principle, wherein the sensor signal of the first sensor, in particular the sensor signals of both sensors, can be fed to a first computing unit of an evaluation electronics arranged within the housing, wherein the sensor signal of the second sensor, in particular the sensor signals of both sensors, can be fed to a second computing unit of the evaluation electronics, wherein the first computing unit is designed to determine a first value of the speed of the movable part from the sensor signal of the first sensor, wherein the second computing unit is designed to determine a second value of the speed of the movable part from the sensor signal of the second sensor and to monitor it for exceeding a permissible extent of deviation from the first value, wherein the first sensor is a radar sensor and the second sensor is a light sensor, wherein the housing is configured in such a way that the light beams emitted and received by the light sensor can penetrate a transparent region of the housing, and wherein the transparent region of the housing is a portion of the housing and the radar sensor is further away from the transparent portion than from the rest of the housing, which in particular is opaque to light.