PTZ Camera Coverage Radius on a Jobsite — Aim, Zoom, and Blind Spots

The industry standard (Australian AS 4806) defines three tiers:

Identification — you can identify a specific individual from footage. Requires 80+ pixels per foot of subject.

Recognition — you can recognize a known person or vehicle. Requires 20 pixels per foot.

Detection — you can see there's a person or vehicle. Requires 4 pixels per foot.

• Identification: 80+ ppf — 200–400 ft with 4K PTZ
• Recognition: 20 ppf — 400–800 ft with 4K PTZ
• Detection: 4 ppf — 600–1,200 ft with 4K PTZ
• Standard: Australian AS 4806 (industry norm)

Standard spec: 4x 4K PTZ cameras with 30x optical zoom and auto-tracking. Mount height: ~22 feet on the extended mast.

That mount height + zoom range gives identification-grade coverage across a 4-acre rectangular site with the four cameras aimed at 90-degree quadrants.

Directly under the trailer (0–25 feet radius) is a natural blind spot with a fixed-position PTZ. Guardtress deployments address this with a downward-fixed camera on the trailer chassis or a supplementary pole-mounted camera 40 feet from the trailer.

Corners of an irregular site beyond 400 feet from the trailer are the other common blind spot. Address with pole cameras or a second trailer.

• Under-trailer blind spot: 0–25 ft — fix with chassis cam
• Beyond-radius corners: fix with pole cam or 2nd trailer
• Perimeter fencing shadows: plan around at deployment
• Adjacent building shadows: rotate camera position seasonally

Four cameras at 90-degree quadrants is the default. On irregular sites, aim adjusts to concentrate on high-value zones and known intrusion paths.

Auto-tracking follows a subject once detected — the camera zooms and pans to keep the target in identification-grade frame through their movement across the site.

Standard Guardtress deployments across the Houston metro land in 24–72 hours from signed quote to live monitoring. A single solar-powered mobile security trailer covers roughly 1.5–2 acres of open ground, carries 5–7 days of no-sun autonomy, and runs on bonded cellular so it needs no site power, no trenching, and no permanent mounting. Units relocate with a standard pintle hitch as the work front moves — a real advantage on phased Houston builds where the exposure point changes every few weeks.

Every unit ships with license plate recognition (LPR), analytic tripwires tuned to human and vehicle shapes, and two-way talkdown from a live U.S.-based monitoring center. Verified events escalate to the Houston Police Department or the Harris County Sheriff's Office as a confirmed crime in progress, which moves the call up the priority queue instead of into the false-alarm pile. Site plans, camera angles, and escalation contacts are set during a 30-minute assessment before the trailer leaves the yard.

• Assessment to live monitoring: 24–72 hours
• Coverage per unit: 1.5–2 acres, 360° with LPR at entry
• Power: solar with 5–7 days no-sun autonomy, no site power required
• Escalation: verified talkdown, then HPD / Harris County Sheriff dispatch
• Service area: Houston, Sugar Land, The Woodlands, Pasadena, Baytown, Conroe, Katy, Galveston, League City, Pearland

Houston contract guards run roughly $28–$42 per hour loaded, so a single unarmed guard on a 12-hour night shift costs about $10,000–$15,000 per month — for one set of eyes that can only be in one place, takes breaks, and turns over often. A monitored Guardtress trailer covers the same perimeter continuously at a fraction of that, and the spend moves from a headcount line to a predictable OPEX line you can hold to the schedule.

The math usually turns on two numbers: what a single loss event costs you in materials plus schedule slip, and whether your carrier offers any credit for a written 24/7 monitoring plan — a question worth asking your broker directly. Full site-by-site pricing is in our construction site security cost guide, and the head-to-head breakdown is at Guardtress vs. security guards.

• Houston guard rate: $28–$42/hour loaded
• One 12-hour guard shift: $10,000–$15,000/month
• Monitored trailer: fixed monthly OPEX, no overtime or turnover
• Builder's risk documentation: written monitoring plan formatted for broker review