Common Causes of Struck-By Accidents

Struck-by accidents around heavy equipment share a striking trait: they are rarely random. Behind almost every incident lies a predictable set of conditions that put a worker on foot and a moving machine in the same space at the same moment. When you understand these root causes, you can target them directly and build a prevention program that addresses the real problem rather than the symptom.

This guide breaks down the most common causes of struck-by accidents on jobsites, why each one persists even on well-run operations, and how you can close the gaps they create. For a broader overview of what these incidents are and how they are classified, see What is a Struck-By Incident?

Blind spots are the single largest contributor to struck-by incidents around heavy equipment. Every large machine has zones the operator simply cannot see from the cab, created by the size of the body, the position of the seat, and the attachments or loads the machine carries.

• They exist on every machine. Loaders, excavators, dump trucks, dozers, forklifts, and telehandlers all have areas the operator cannot view directly, particularly behind and along the sides.
• They grow with machine size. On a larger machine, the area a driver cannot see can extend well beyond the length of the vehicle, easily concealing a worker standing directly behind it.
• They are not always an operator failure. A skilled, attentive operator managing a load, a work sequence, and a schedule still cannot see a worker standing in a zone the cab physically blocks from view.

Because blind spots are a matter of machine geometry rather than human error, they cannot be trained away. They can only be managed. For a deeper look at how to address them, see Blind Spot Risks and Awareness.

Active jobsites are demanding environments, and the conditions that define them work directly against safe operation. Even where a worker would normally be visible, environmental factors can hide them at the worst possible moment.

These conditions are especially common:

• Dust. Airborne dust from excavation, hauling, and material handling reduces how far and how clearly an operator can see. On mining and aggregate sites, dust can obscure a worker within a short distance of the machine.
• Low light. Early mornings, night shifts, and poorly lit work areas cut visibility sharply. High-visibility apparel helps, but it still depends on the worker being within the operator's line of sight.
• Noise. Constant engine noise, backup alarms, and equipment operation make it difficult for workers to hear approaching machines and for operators to catch verbal warnings. This can also lead to noise fatigue.

Dust

Low Light

Noise

These conditions rarely appear one at a time. A dusty, noisy site at dusk stacks multiple visibility challenges together, and each one narrows the operator's ability to detect a worker before contact.

Where a worker stands relative to a machine often determines whether they are safe or exposed. Struck-by incidents frequently occur when a worker on foot enters a danger zone without the operator's awareness.

Many struck-by incidents trace back to a breakdown in communication between the operator and the workers on foot around the machine. When both parties do not share the same understanding of who is where and what happens next, the margin for error disappears.

These gaps take several forms:

• Clear or inconsistent signals. When hand signals are not standardized and confirmed, an operator may misread an instruction or begin moving before a worker is clear.
• Assumed awareness. A worker may assume the operator has seen them, while the operator assumes the area behind the machine is empty. Both assumptions can be wrong at the same time.
• Spotter Limitations. Spotters add real value, but their attention can lapse during long shifts, and they introduce another person into the hazard zone.
• Noise Interference. As noted above, a busy site can drown out verbal warnings exactly when they matter most.