Being Struck by Excavator Boom or Bucket During Slewing
highExcavator booms swinging through their arc of rotation create dynamic strike zones where ground workers can be fatally crushed if they enter the swing radius during operation. A 20-tonne excavator boom with attached bucket can weigh 3-4 tonnes and extends 8-12 metres from the machine centerline, sweeping through a circular area of 200-450 square metres depending on boom configuration. The momentum of swinging booms makes them impossible to stop instantly when operators perceive collision risks, with reaction time plus hydraulic response time meaning 2-3 seconds elapse between operator perception and boom motion cessation. Workers performing tasks including concrete placement, pipe laying, formwork installation, or supervision may enter swing zones inadvertently, particularly when focused on their immediate tasks rather than equipment movements. Excavator operators have limited visibility of their full swing radius, with A-pillars, counterweights, and equipment structure creating substantial blind spots where workers become invisible to operators. The combination of limited visibility, momentum-driven collision forces, and multiple ground workers operating in proximity to excavators makes struck-by incidents the leading cause of mobile plant fatalities on Australian construction sites.
Consequence: Fatal crushing injuries when workers are struck by swinging booms or buckets, with collision forces of several tonnes causing instantaneous death, serious crushing injuries to limbs and torso even from glancing contact with boom structures, multiple casualties when operators are unaware of several workers in swing zones, and psychological trauma for operators and witnesses involved in fatal struck-by incidents.
Equipment Rollover on Slopes and Unstable Ground
highEarthmoving equipment operating on slopes, near excavation edges, or on ground with inadequate bearing capacity faces rollover hazards that can crush operators and destroy equipment. Excavators are particularly vulnerable when operating with boom extended to one side on slopes, creating asymmetric loading that shifts the centre of gravity outside the stability triangle defined by track positions. Loaders carrying loaded buckets uphill or turning while climbing slopes can exceed stability limits, with front-heavy loading during bucket carry creating forward tip-over risks. Bulldozers working across slopes rather than up/down slope contours face lateral rollover risks, particularly on loose or disturbed material. Ground bearing capacity failures can occur suddenly when equipment operates over buried voids, inadequately compacted fill, or saturated soils, with ground collapsing beneath equipment causing it to tip into voids or slide down slopes. Edge loading near excavation walls creates collapse risks as equipment weight exceeds soil bearing capacity near unsupported edges. Weather conditions including rain reducing traction and softening ground surfaces, and ice or frost affecting stability on slopes, significantly increase rollover likelihood.
Consequence: Fatal crushing of operators when equipment inverts and cab structures are compressed or operators are ejected and crushed beneath equipment, serious crush and impact injuries even with ROPS and seatbelt protection due to violent rollover dynamics, destruction of earthmoving equipment valued at $200,000-$2,000,000 requiring replacement, and extended project delays during incident investigation and equipment replacement procurement.
Underground Service Strikes During Excavation
highExcavation activities using earthmoving equipment create risks of striking underground services including high-voltage electrical cables capable of causing electrocution and fire, gas pipelines that can explode or release toxic/flammable gas, water mains causing flooding and service disruption, telecommunications cables disrupting essential services, sewer lines releasing sewage and creating environmental contamination, and fibre optic cables causing data service outages. Despite dial-before-you-dig services providing service location information and requirements for potholing to physically verify service positions, service strikes remain common due to inaccurate service records, unmarked services installed without proper documentation, services deflected from shown positions during previous works, and human error when interpreting service information or controlling excavation. The precision required for excavation near services exceeds normal operator capability when using buckets—a 600mm wide bucket can strike services when positioned 300mm horizontally from service location due to bucket width. Excavation depth control is challenging without laser or GPS guidance systems, with bucket teeth potentially penetrating services located shallower than shown on plans.
Consequence: Electrocution of operators and ground workers when excavators strike high-voltage cables energizing equipment and creating step potential zones lethal to nearby workers, explosions and fires when gas lines are ruptured with ignition sources present, service disruptions affecting thousands of customers for extended periods, massive financial penalties imposed by service authorities for service damage ($50,000-$500,000 per incident), criminal prosecution under electrical safety legislation for strikes on electrical assets, and project delays while emergency repairs are completed and investigations conclude.
Contact with Overhead Powerlines
highEarthmoving equipment with elevated components including raised loader buckets, excavator booms, and tipper bodies can contact overhead powerlines causing electrocution of operators and nearby workers. Australian electricity networks operate at various voltages including 230/400V low-voltage lines, 11kV and 22kV high-voltage distribution lines, and 66kV, 132kV, or higher transmission voltages. Equipment contact with any voltage level can cause fatal electrocution, with higher voltages able to arc across air gaps before physical contact occurs. Operators concentrated on ground-level activities may not maintain awareness of overhead bucket or boom positions, particularly when boom movement is required to follow traveling equipment. Travel routes beneath overhead lines create repeated hazard exposure with each equipment pass. The legislated minimum approach distance of 6 metres from overhead lines for uninsulated equipment and untrained personnel creates substantial clearance requirements often incompatible with site access constraints, forcing difficult decisions about powerline relocation or equipment operational restrictions. Excavator booms conducting electricity create electrified zones around equipment with step potential that can electrocute workers up to 10 metres from contact point. Electrical arcing creates intense heat causing fires in hydraulic systems and fuel tanks, often trapping operators in burning equipment.
Consequence: Fatal electrocution of equipment operators when booms, buckets, or elevated components contact powerlines, electrocution of ground workers attempting to assist operators or who are within step potential zones around energized equipment, massive electrical faults causing widespread power outages affecting thousands of customers, severe burns from electrical arcing and fires in equipment, permanent disability for survivors of electrical contact including amputation and neurological damage, and criminal prosecution of PCBUs and officers for breaches of electrical safety legislation.
Visibility Limitations and Blind Spots
mediumAll earthmoving equipment has substantial blind spots where operators cannot see ground workers, obstacles, or hazards despite using mirrors and visual aids. Excavators have major blind spots immediately adjacent to tracks where counterweights and boom structures obstruct visibility, directly behind the machine where operator seats face forward during travel, and in the arc of boom swing where A-pillars and equipment structure create obstructed sight lines. Loaders have very limited rear visibility due to raised engines and operator cab positioning, requiring complete reliance on mirrors or cameras for reversing operations. Bulldozers have almost no visibility directly in front of blades when blades are raised, with blade height obscuring ground immediately ahead requiring operators to blade-down before stops. Environmental conditions including dust from excavation activities, rain on windows and mirrors, sun glare on glass surfaces, and fog or darkness in early morning create additional visibility impairment. The dynamic construction environment means hazards and workers move constantly into and out of operators' fields of view, with momentary distraction causing operators to lose situation awareness. Modern equipment fitted with cameras and proximity sensors improves but does not eliminate visibility limitations, with cameras providing two-dimensional view lacking depth perception and sensors only detecting very close objects.
Consequence: Workers struck by reversing or traveling equipment resulting in fatal crushing injuries, collisions between earthmoving equipment and light vehicles or other plant, equipment striking stockpiles, excavation edges, or structures causing damage and potential equipment tip-over, loads being placed on workers or structures with operators unaware of impending contact, and continuing normalisation of poor visibility practices where operators rely on luck rather than positive clearance verification.
Hydraulic System Failures and Fluid Injection
mediumEarthmoving equipment hydraulic systems operate at extreme pressures typically 280-350 bar (4,000-5,000 psi) enabling powerful bucket and boom operation. Hydraulic hose failures can occur from mechanical damage, age deterioration, contamination causing internal wear, or exceeding pressure ratings. Failed hoses release high-pressure hydraulic fluid as fine spray capable of penetrating human skin, with fluid injection injuries causing tissue destruction requiring amputation of affected limbs. Checking for hydraulic leaks using hands to feel for spray causes injection injuries, with pinhole leaks invisible to naked eye creating injection risks. Hydraulic fluid spraying onto hot exhaust components or engine surfaces creates fire hazards, with mineral oil-based hydraulic fluids igniting readily when heated to autoignition temperatures around 300°C. Sudden boom or bucket drop caused by hydraulic failure creates crushing risks for workers beneath equipment, with boom structures weighing several tonnes falling from height generating fatal impact forces. Equipment repairs conducted without proper hydraulic isolation procedures expose maintenance workers to stored energy hazards from pressurized hydraulic systems.
Consequence: Fluid injection injuries requiring surgical debridement and frequently amputation of affected fingers or limbs, fires caused by hydraulic spray ignition resulting in equipment destruction and burn injuries to operators, fatal crushing when hydraulic failures cause boom drops onto workers below, and permanent disability from hydraulic fluid injection even with immediate medical treatment due to tissue destruction from pressurized fluid.
