Struck-By and Caught-In/Between Hazards

Defining the Last Two of the Fatal Four

The Fatal Four are falls, struck-by, caught-in/between, and electrocutions, together causing about 60% of construction deaths (BLS CFOI). This section covers the two that are easiest to confuse on the exam.

• Struck-by: injury from forcible contact with a moving object — flying, falling, swinging, or rolling. Examples: a falling tool, a swinging crane load, a nail from a nail gun, a backing dump truck, a collapsing wall fragment.
• Caught-in/between: injury when a worker is squeezed, caught, crushed, pinched, or compressed between two or more objects, or buried. Examples: trench cave-in, being pinned between a truck and a wall, an unguarded machine pulling in a hand.

The exam's favorite distinction

The test rule: if the injury comes mainly from the impact of the object, it is struck-by. If the injury comes from being crushed or caught between objects (or buried), it is caught-in/between. A worker pinned between a backing forklift and a stack of pipe is caught-in/between, not struck-by, because the harm is the crushing — a classic trap.

Struck-By Categories and Controls

OSHA groups struck-by into four sub-types:

Vehicle and traffic controls

Work zones with mobile equipment require:

• High-visibility apparel meeting ANSI/ISEA 107 for anyone exposed to traffic or equipment.
• A spotter and an internal traffic control plan (ITCP) to separate workers from equipment.
• Functioning backup alarms or a spotter when an operator's view to the rear is obstructed.
• Barricades and signage per the MUTCD for public road work.

High-visibility apparel is rated by class: Class 2 for moderate-traffic and roadway work, and Class 3 (more reflective material, full sleeves) for high-speed traffic or low-light conditions. A flagger directing traffic on a highway needs at least Class 2, and often Class 3 at night — a detail the exam may probe.

Falling-object protection

When workers are below overhead work, protect them with toeboards (minimum 4 inches in vertical height, per 1926.502(j)), screens, debris nets, canopies, and hard hats (ANSI Z89.1). Barricade the danger zone beneath the work so no one stands under suspended or overhead loads. The danger zone should account for the load's swing radius and the path a dropped object could bounce or roll.

Caught-In/Between Categories and Controls

The major caught-in/between hazards a supervisor must control:

1. Trench/excavation cave-ins — the deadliest; controlled by sloping, shoring, or shielding (Subpart P).
2. Unguarded machinery — rotating parts, augers, gears, belts; controlled by machine guarding and lockout/tagout during servicing.
3. Pinning hazards — being caught between equipment and a fixed object, or between two pieces of equipment; controlled by spotters, blocking, and standing clear of pinch points.
4. Collapsing materials or structures — wall sections, masonry, formwork; controlled by bracing and shoring.

Nail guns and powder-actuated tools

Flying-object struck-by injuries often come from pneumatic nail guns and powder-actuated tools. Controls the supervisor must enforce:

• Use sequential-trip triggers (not bump/contact triggers) for most framing to prevent unintended double-fires.
• Require eye and face protection (ANSI Z87.1) for the operator and nearby workers.
• Powder-actuated tool operators must be trained and certified and carry a card.
• Never point a tool at anyone; treat it as loaded.

Machine guarding for caught-in

Under Subpart I (1926.300), exposed moving parts — belts, gears, chains, rotating shafts, points of operation — must be guarded. A worker whose sleeve is pulled into an unguarded auger suffers a caught-in injury. Guards must be secured, not easily removed, and not create a new hazard. During servicing, guarding is replaced by lockout/tagout so the machine cannot start.

Cranes, Rigging, and Steel Erection

Many struck-by and caught-in events involve lifting:

• Subpart CC (Cranes): keep loads at least 10 feet from power lines up to 50 kV; use a signal person when the operator's view is blocked; never stand under a suspended load.
• Subpart R (Steel Erection): fall protection is required above 15 feet for most workers; connectors between 15 and 30 feet must be provided fall-protection equipment and training.
• Subpart T (Demolition): a written engineering survey by a competent person must be completed before demolition begins to assess collapse potential.

Step-by-Step: Setting Up a Drop Zone

A supervisor controlling overhead-load risk should:

1. Identify the swing radius and load path.
2. Barricade the area below and downrange of the load.
3. Post a signal person and use tag lines to control the load.
4. Keep all non-essential workers out of the zone.
5. Require hard hats and verify rigging before each lift.

Common Mistakes

• Calling a crushing/pinning injury "struck-by" — if the harm is being caught/crushed, it is caught-in/between.
• Forgetting steel erection uses a 15-foot trigger, not 6 feet.
• Allowing workers under suspended loads.
• Skipping the demolition engineering survey.
• Treating high-visibility apparel as optional around mobile equipment.