20th June 2025
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6 minutes
Real-time alerts for pedestrian workers in close proximity to moving machinery are a critical component of modern site safety. These systems drive behavioral change and prevent accidents but only when alerts are trusted and acted upon. One of the most significant barriers to effectiveness is alarm fatigue, where excessive or poorly calibrated warnings lead workers to ignore alerts entirely. But what do we really mean when we say “too many alarms”?
Strictly speaking, a false positive occurs when an alert is triggered unnecessarily; i.e., when there is no actual risk. The SensorZone multiband radio frequency system is specifically designed to minimize these incidents. It uses a secure “handshake” between the pedestrian tag and the base station, which prevents alerts caused by radio interference or background noise. As a result, the risk of genuine false positives with SensorZone is extremely low.
However, in practical terms, many users refer to any unwanted alert as a false positive. These typically arise not from system errors, but from misaligned zone calibration.
The most common source of unwanted alerts is improperly set detection zones. SensorZone offers precise zone calibration, with adjustable ranges from 2 to 10 metres per antenna. Before installation, a thorough application assessment must be completed to define the hazardous area around each vehicle or machine. The system should then be calibrated to reflect this assessed danger zone focused on keeping this to a minimum acceptable level.
A common misconception is that a larger detection zone equals a safer worksite. In reality, overly large zones increase the number of alerts in low-risk areas, which can desensitize workers. When alerts do not correspond to real, immediate danger, they become a nuisance and safety suffers as a result.
Another key source of perceived false positives stems from the disconnect between risk assessments and worker experience. For example, if operators have regularly worked within 5 metres of a machine without incident, they may view that space as safe, even if it falls within the risk zone identified by safety teams.
To address this, it is essential to involve workers during the design and calibration phase. Their on-the-ground experience offers valuable insight into how tasks are actually performed. This collaboration ensures the system supports “work as done,” not just “work as imagined.”
Safety professionals understand that tasks evolve over time. Procedures adapt, and the way work is carried out on site often diverges from original plans or risk assessments. This gap creates both safety vulnerabilities and friction with automated systems like Proximity Warning Systems (PWS). If the system alerts during a routine task, workers may dismiss the warning as erroneous, even when it's functioning correctly.
True false positives are rare in well-designed systems like SensorZone. More often, issues arise from misunderstandings about when the system should alert. The solution lies in precise calibration based on actual risk, and clear, collaborative engagement with workers during implementation.
