Case Study 77: Working Around Mobile Plant. Blind Spots and Exclusion Zones
Incident Overview During a site safety demonstration, an excavator (180° plant) was positioned centrally with clearly marked blind spot, exclusion zone, and safe zone areas. Cones, barriers, and signage were used to visually show how quickly visibility is lost around mobile plant. Operatives were asked to stand at various positions around the machine while the operator remained seated in the cab. From ground level, the machine appeared fully visible. From the cab, several workers disappeared completely from view, even at short distances. This exercise reflected a common live-site condition where workers believe they are “seen”, while in reality they are positioned directly inside blind spots. What Went Wrong On active construction sites, similar plant is often operating: ●Excavators (180° / 360°) ●Forklifts ●Roto 360 telehandlers Workers frequently enter the operating radius to guide, observe, or “just pass through”. Exclusion zones may exist on paper, but are not always respected or actively controlled. If a worker can enter a blind spot, the exclusion zone has failed. The risk increases when: ●The plant is slewing or reversing ●Attachments obstruct the operator’s view ●Ground workers assume eye contact equals visibility ●Exclusion zones are not physically enforced Key Hazards Identified ●Operator blind spots on all sides of the machine ●Crushing risk during slewing or reversing ●Workers standing within the machine’s operating radius ●False sense of safety due to proximity and familiarity ●No single person controlling the exclusion zone Any of these conditions can result in striking, trapping, or crushing injuries. Key Lessons Learned ●If you can see the machine, it does not mean the operator can see you ●Blind spots exist even on modern plant ●Exclusion zones must be physical, not verbal ●Standing “just outside” is still inside the risk Safety Recommendations ●Establish clear exclusion zones using barriers, cones, and signage ●Never rely on eye contact or assumptions of visibility