Abstract: Safety apparatus is disclosed for a crane including a crane body that rotatably swings about a substantially vertical axis about an undercarriage that moves on endless tracks. The crane body has opposed sides, a front end and back end, and a crane boom projects forwardly from the front end. The safety apparatus includes a length of cable that is supported in spaced relation from the crane body, extending around a portion of its periphery consisting of the crane body sides and back end. The cable is supported in such a manner that it may be laterally deflected, by a person or object, which alters its effective length. The safety apparatus further includes a control device that is operably connected to the cable for generating an electrical alarm signal in response to cable deflection, and an audible alarm connected to the control means for generating an audible alarm in response to the alarm signal.