An apparatus for mobile machinery includes a sensor module configured for detachable fitment to mobile machinery, and a control module configured to interface with a control system of the mobile machinery. The sensor module includes an orthogonal sensor arrangement for sensing obstacles in three-dimensional space, an orthogonal indicator arrangement configured to provide a gradient proximity indication of an obstacle, and a wireless transceiver arranged in signal communication with the sensor and indicator arrangements. The control module includes a control wireless transceiver for communicating with the wireless transceiver of the sensor module, and a processor in signal communication with the control wireless transceiver, the processor configured to program, via the wireless transceiver of each sensor module, the sensor and indicator arrangements and with predetermined thresholds of obstacle proximity. If a sensed obstacle proximity exceeds a maximum threshold, the processor overrides the control system to facilitate situational awareness of an operator.

A warning sign arrangement for a vehicle, comprises a warning sign, a warning sign hiding device comprising an electric locking mechanism, the warning sign hiding device being configured to hide the warning sign when the electric locking mechanism is active, and to expose the warning sign when the electric locking mechanism is deactivated, The electric locking mechanism comprises a first electric lock configured to be powered by a main electric power supply of the vehicle, and a second electric lock configured to be powered by a backup electric power supply of the vehicle, wherein both of the first electric lock and the second electric lock must be deactivated to expose the warning sign.