A restricted zone on a plant drawing is a line. On the floor it is a painted boundary that someone crosses forty times a shift, usually for a good reason and occasionally for a bad one. Restricted area monitoring puts a camera-based check on that line so the crossing is recorded and, where it matters, alarmed within seconds instead of surfacing in a near-miss report a week later.
WHY THE ZONE FAILS
The Gap Between A Marked Boundary And A Controlled One
Machine guarding and lockout/tagout sit permanently near the top of OSHA’s most cited standards. Lockout/tagout alone drew 2,177 citations in FY 2025, and OSHA estimates the standard prevents roughly 120 fatalities and 50,000 injuries a year (Advanced Safety & Industrial Supply). The common thread in those cases is presence: a person in a place where stored energy, a moving part, or a forklift aisle was assumed to be free of people.
Under the ISO 45001 hierarchy of controls, paint, signage and toolbox talks are administrative controls, which the standard ranks below engineering controls precisely because they depend on worker behaviour to work (Advisera). Camera-based zone monitoring does not move a hazard up that hierarchy. What it does is measure how often the administrative control is being ignored, and give the people responsible for the area a signal at the moment of entry rather than a count at the end of the month.
That distinction matters when you are asked to justify the spend. The system produces evidence and response time. Physical guarding, interlocks and light curtains produce protection. Most plants that deploy zone monitoring well are using it on areas where fixed guarding is impractical: an outdoor tank farm, a crane load path, a chemical store, a maintenance bay whose boundary changes with the job.
WHAT IT SEES
Detection, Zones And Rules
ARSA Basic Safety Guard treats a restricted area as a region of interest drawn on a specific camera view, with its own rule set. A human entering that region raises an event. Because zones are per camera and per rule, one camera covering a transfer aisle can carry a permanent exclusion zone around a press and a time-based rule on the aisle itself, so that a pallet truck route is unremarkable at 09:00 and alarmable at 23:00.
Events leave the system the way your site already works. The AI Box fires to its local dashboard, a siren relay, a webhook, or whatever alerting stack you already run. The software edition ships the same events as JSON over webhook or REST, with camera, zone, class and confidence in the payload, plus CSV and PDF export for the audit trail.
Three things this does not do, stated plainly because someone will ask.
It Does Not Identify Who Crossed
The zone rule fires on a person. Matching that person to an employee record is a separate capability with far harsher camera requirements, and it is not what Basic Safety Guard’s zone module provides.
It Does Not Detect Weapons Or Intent
ARSA does not sell weapon or firearm detection. If a vendor comparison put that on your requirements list, it will not be met here, and you should discount any claim that a general person detector covers it.
It Does Not Stop Anybody
The system raises an event. Interlocking a machine or a door off that event is an integration your controls engineer designs and owns, with its own functional safety assessment. Detection latency and camera failure modes are not appropriate as a primary protective function.
THE NUMBERS
What The Camera Has To Deliver
Restricted-zone intrusion is one of the least demanding analytics ARSA runs, because a person-shaped object at the boundary is a much coarser target than the edge of a hard hat. The governing figure in ARSA-CVS-001 is pixel density at the point where the rule must work, written as pixels per metre.
| Requirement | Restricted-Zone Intrusion | Safety Helmet Present Or Absent |
|---|---|---|
| Pixel density at target | 71 PPM | 262 PPM |
| Camera tilt below horizontal | Optimal 15 to 40°, maximum 55° | Optimal 10 to 25°, maximum 35° |
| Minimum light at target | 10 lux | 50 lux |
| Maximum range, 2 MP, 60° lens | 23.6 m | 6.3 m |
| Maximum range, 4 MP, 60° lens | 31.4 m | 8.4 m |
| Maximum range, 8 MP, 60° lens | 47.1 m | 12.7 m |
Read those two columns together, because the practical consequence is the whole reason this article exists. A 2 MP camera on a 60 degree lens covering a 20 metre yard will hold a zone rule across that yard and will fail helmet detection past 6.3 metres. Plants routinely discover this the wrong way round, having specified one camera position to do both jobs. Zone coverage and PPE compliance are usually different mounting distances on the same site, and sometimes different cameras.
Tilt is the other thing people get wrong. Zone intrusion tolerates a steep view down to 55 degrees, because the rule only needs a person to be resolvable inside a boundary. PPE analytics are prohibited above 45 degrees, since the wearer’s own body hides the helmet, the vest front and any harness strap. A camera mounted high for tamper resistance is often a perfectly good zone camera and a useless PPE camera. The full table for every analytic function, along with the camera settings we ask sites to change, is published at /system-requirements/, and the lens and field of view visualiser will show you what a given lens actually covers at your standoff before you buy anything.
Cameras must meet 2 MP minimum, 4 MP recommended, 15 fps minimum on the analytic stream, with IP66 and IK08 for outdoor cabinets. Infrared illumination is acceptable for zone rules, which depend on shape rather than colour. Any colour-coded rule, hi-vis vests included, needs white light at night.
HOW IT DEPLOYS
Hardware, Licensing And Where Processing Happens
Detection runs on site. The AI Box Mini handles up to three camera streams at $1,890, the AI Box Server up to 25 at $10,900, and the Basic Safety Guard licence is $1,350 per camera perpetual or $45 per camera per month. If you already run servers with CUDA-capable GPUs, the software edition deploys as Docker containers against your ONVIF or RTSP streams at the same per-camera licence, with a four-camera minimum. Camera hardware is not included in either path. The AI Box Series page sets out both configurations.
Video stays inside your network in both cases. What crosses the boundary, if you configure it to, is metadata: timestamps, camera and zone identifiers, event classes, and where enabled small cropped images. For defence and government sites that requirement is usually absolute, and the appliance is the only device bridging the camera VLAN.
Before committing, a Remote Camera Design Review at $1,500 returns a pass or fail against ARSA-CVS-001 for each camera position, with priced remediation where a position fails. On-site survey is $4,500 plus travel for up to 50 cameras. Both fees are deducted from the project fee if you contract within 90 days. Engagement tiers are listed on /services/.
Frequently Asked Questions
Can My Existing 2 MP Cameras Do Restricted Area Monitoring?
To 23.6 metres on a standard 60 degree lens, yes. Distance decides this, not the sensor alone. A narrower lens roughly doubles the reach while halving the width covered, which suits a long aisle and suits a wide yard poorly. Send the camera schedule with mounting distances and the Design Review returns a verdict per position.
Will It Work At Night?
Zone intrusion needs 10 lux at the target and works under infrared, because the rule depends on the shape of a person rather than colour. Hi-vis vest detection and any other colour-coded rule stop working under infrared and require white light at the target plane.
Can We Allow Entry During Some Hours And Alarm It In Others?
Yes. Zone rules carry time-based access rules, so the same boundary can be permitted on day shift and alarmed overnight. Different zones with different rules can sit on one camera view.
Does It Tell Us Who Entered The Zone?
The zone module reports that a person entered, with camera, zone, timestamp and confidence. It does not attach an identity. Identity matching is a separate capability with much steeper camera requirements and should be scoped as its own question.
Does ARSA Detect Weapons Or Intruders Carrying Objects?
No. ARSA does not offer weapon or firearm detection in any product line. Restricted area monitoring here means detecting a person inside a defined zone under defined rules.
How Are Events Audited For A Regulator Or Insurer?
Every event is logged with timestamp, camera, zone and detection class, and exports as CSV or PDF. Retention is configured by your administrator against your own storage allocation.
Draw The Zone, Then Measure It
Restricted area monitoring earns its place when you can say how many times last month someone stood where the risk assessment says nobody stands. Basic Safety Guard runs that check on the cameras already covering the plant, on hardware in your own cabinet, with the footage staying where it is.
See Basic Safety Guard for hardware configurations, licensing and the full site requirements.