AI Safety Monitoring: Camera vs Sensor vs Wearable Compared
Camera-based systems excel at PPE compliance and zone monitoring on open sites, wearable sensors are strongest for heat stress and fatigue in confined spaces, and fixed environmental sensors handle air quality and noise. No single category covers all hazards, and most mid-size jobs need at least two.
Three years ago I put safety cameras on a mid-size commercial job after a near-miss with unsecured floor openings. Two years ago I trialed wearable clips on a bridge rehab project with a tight confined-space component. Last spring I used fixed sensors on a demo project where air quality was the primary concern. After running all three approaches on real jobs, I have a clearer picture of what each one actually does — and where each one falls apart.
This is not a vendor comparison. It is a category comparison. I will name specific products where they are the clearest example of a category, but the point is to help you pick the right type of system before you start evaluating vendors within it.
OSHA data consistently shows falls, struck-by incidents, and caught-in/between events account for roughly 60% of construction fatalities in a given year. All three monitoring categories claim to address these hazards. They do not address them equally, and they do not work in the same environments.
How I Evaluated Each Category
I used four criteria that matter for day-to-day operations, not just demo conditions:
Coverage reliability. Does the system actually detect hazards when the site is noisy, dusty, crowded with workers, or reconfigured after the first week? Systems that work beautifully in controlled pilots often degrade quickly when your site conditions look like an actual construction job.
Alert actionability. When the system fires an alert, can your superintendent do something with it in time? An alert that takes 15 minutes to surface is not the same as one that appears in 30 seconds.
Worker friction. Any system that workers actively defeat or forget to use is not a safety system — it is a liability audit trail. Compliance rates matter more than feature lists.
Total cost of ownership. Upfront hardware is rarely the biggest number. Software subscriptions, IT support, and the time cost of managing the platform matter.
Camera-Based AI Monitoring
How it works: Fixed cameras at key site locations feed video into an AI model that identifies unsafe behaviors — no hard hat, no vest, workers in exclusion zones, unsecured openings, improperly stacked materials. Products in this category include Intenseye, Voxel (now part of Samsara), and Buildots when configured for safety overlays.
Coverage reliability: High for the specific zones you cover. The critical limitation is field of view. A camera covering the east side of a floor deck does not see what is happening on the west side. On a site with significant vertical work or multiple active levels, you need more cameras than vendors typically quote in their initial proposals. Budget for 30-40% more coverage points than the site plan suggests you need.
False positive rates are real. In high-traffic areas with workers moving quickly, the models can generate 40-60 alerts per shift, a large portion of which are misclassifications. You need someone to triage this. Sites that set up camera monitoring and then do not assign anyone to review and tune the alert thresholds end up ignoring the system within 30 days.
Alert actionability: Good. Most platforms surface alerts to a mobile dashboard within 60-90 seconds of detection. Intenseye’s supervisor app sends push notifications with a video clip, which lets a foreman see the violation without walking to the location first.
Worker friction: Low, because workers do not have to do anything. No device to wear, no app to open. This is the category’s biggest practical advantage on large crews with variable turnover.
Where it fails: Underground work, confined spaces, interior work in unlit areas, and any location without reliable WiFi or LTE connectivity. Camera systems require power and network at each camera location. On a horizontal site — utility work, roadway construction, pipeline — the logistics of powering and connecting cameras across a 2-mile right-of-way are prohibitive.
Sensor-Based Monitoring
How it works: Fixed sensors placed throughout a site measure specific environmental conditions: gas concentration (LEL, O2, CO, H2S), noise levels, temperature, structural vibration, or proximity to heavy equipment. Sensors transmit readings to a gateway that triggers alerts when thresholds are exceeded. Products range from BW Technologies gas detection systems to proximity warning systems like Preco Electronics’ PreView Detect for equipment zones.
Coverage reliability: Very high for the specific hazard the sensor measures. A four-gas monitor at a confined space entry gives you continuous, accurate atmospheric data that no camera-based system can replicate. Proximity sensors on excavators and dump trucks catch pedestrian-vehicle conflicts in ways that cameras on fixed structures cannot because the camera moves with the machine.
The limitation is that sensors only detect what they are designed to detect. A well-placed gas sensor tells you nothing about whether workers are wearing their fall protection.
Alert actionability: Excellent for environmental hazards. When a gas sensor trips, the alert is immediate and the required response is clear: stop work, evacuate, investigate. There is no triage ambiguity the way there is with camera-based behavioral alerts.
Worker friction: Variable. Fixed sensors require no worker interaction. Clip-on proximity detection systems like the Triax Spot-r require workers to carry a small device. Compliance rates on clip-on systems run 85-95% on well-managed sites and 50-70% on sites where the safety culture was not strong before the system arrived.
Where it fails: Behavioral safety — nobody is wearing their fall protection, the housekeeping is terrible, workers are taking shortcuts in general. Sensors catch atmospheric and proximity hazards, not the hundred other ways construction workers get hurt.
Wearable AI Monitoring
How it works: Workers wear a device — typically a vest-integrated sensor, a helmet clip, or a wristband — that collects physiological and positional data. Systems vary by focus: Kenzen monitors heart rate, core body temperature estimates, and sweat rate to flag heat stress risk. SmartCap and Fatigue Science products use movement and heart rate variability to flag fatigue. Guardhat integrates gas detection, fall detection, and location into a single helmet-mounted device.
Coverage reliability: Good for individual-level hazards where you have consistent device wear. Because the sensor is on the worker rather than fixed in space, it moves with them across the site, into confined spaces, up scaffolding, wherever they go. This is the category’s primary structural advantage over cameras and fixed sensors.
Fall detection accuracy in wearables has improved significantly. Current devices using accelerometer and gyroscope fusion can distinguish a fall from a worker bending down with roughly 90-95% accuracy in controlled conditions, though field accuracy drops somewhat in high-activity environments.
Alert actionability: Depends on hazard type. Heat stress alerts are excellent — the system can flag rising risk 20-30 minutes before a worker is in acute danger, which gives you time to rotate them out proactively rather than responding to a heat illness. Fall detection is retrospective: it tells you a fall occurred, not that one is about to occur.
Worker friction: This is the category’s biggest weakness. Wearables require consistent, correct use by every worker, every shift. Devices get left in the truck, worn incorrectly, shared between workers, or written off as surveillance. On jobs with high day-labor turnover or multiple subcontractor crews, achieving 90%+ wear compliance is genuinely difficult. Budget time for enforcement and replacement devices — attrition rates on wearable hardware run 10-20% per year through loss and damage.
Where it fails: Sites with high crew turnover, jobs where workers are skeptical of monitoring, and any scenario where you need site-level spatial awareness rather than individual-level data.
Pricing Comparison
| Category | Hardware | Software / Subscription | Typical Site Cost (50-worker job, 6 months) |
|---|---|---|---|
| Camera-based | $1,500–$4,000 per camera | $800–$2,000/month per site | $15,000–$35,000 |
| Fixed sensors | $300–$1,200 per sensor | $200–$600/month per site | $8,000–$20,000 |
| Wearables | $150–$500 per device | $15–$40/worker/month | $14,000–$27,000 |
These are rough ranges based on publicly available pricing and vendor conversations. Camera systems look expensive upfront but require no per-worker costs once installed. Wearables scale linearly with headcount. Fixed sensors depend heavily on which hazards you are monitoring — a gas detection setup for a confined-space-heavy job is different from a proximity warning system for a demo project.
Best For: Recommendations by Scenario
Camera-based AI monitoring is best for: Permanent or long-duration facilities, vertical construction with defined work zones, GCs who need documentation more than real-time response, sites where worker compliance with wearables would be low.
Sensor-based monitoring is best for: Confined space entry programs, any job with atmospheric hazard risk, equipment-heavy sites where pedestrian-vehicle separation is the primary concern, sites where you need defensible, continuous environmental data for OSHA compliance documentation.
Wearable monitoring is best for: Heat-intensive outdoor work where heat stress is the dominant risk, jobs with a stable crew that will consistently wear devices, operations focused on individual physiological monitoring rather than site-wide behavioral compliance.
Honest Verdict
No single category is a complete solution. The sites I have seen get the most value from AI safety monitoring use two categories together — typically cameras for behavioral compliance in defined work zones paired with either sensors or wearables for the hazard type that cameras cannot address.
If you are picking one and your budget is limited, start with the category that addresses your actual injury history. If you have had near-misses with pedestrian-equipment conflicts, proximity sensors pay back faster than cameras. If heat illness has been a problem in past summers, wearables make more sense than cameras. Cameras are a better fit when your biggest compliance gap is PPE adherence and housekeeping in areas you cannot be in constantly.
The honest trade-off in all three categories is that the systems that require the least from workers (cameras, fixed sensors) also have the least visibility into individual-level risk, and the systems that provide the richest individual data (wearables) depend entirely on consistent human behavior to work. That tension does not go away. It just shifts based on which category you choose.