Type 09 · Structural steel
Steel that is out by an inch is out for the life of the building
The drone flies the frame instead of a crew climbing it. Anchor bolts before the columns land, plumb and bay dimensions as they go up, bolt counts at every connection, weld coverage, deck placement and fireproofing — all measured in blue laser against the erection drawings, at height, with nobody in a harness.
The system
Bolts → erection → connections → record
Pre-steel
Anchor bolt patterns and base plate elevations verified before the first column is picked.
During erection
Daily flights capture plumb, bay dimensions and top-of-steel as the frame rises.
Connections
Macro imaging counts bolts and reads weld coverage at every joint, at height.
Record
A dimensioned as-built frame handed to management before it is clad or fireproofed.
Anchor bolts · base plates
Check the bolts the day before the crane, not the day of
Every pier is scanned and the bolt group compared to the anchor bolt plan: spacing in both directions, bolt-circle diameter, rotation of the pattern, thread projection and base plate elevation. A group that is out gets fixed with a template and epoxy the day before the crane is on the clock — not discovered by an erection crew holding a column in the air.
- Bolt patternSpacing and bolt circle
- RotationPattern orientation vs plan
- ProjectionThread length above the pier
- Plate elevationTied to site control
- Grout & shimsPack condition and stack height
Cost of not catching it
A crane crew standing down while a bolt group is re-drilled costs thousands per hour before anyone touches the schedule. Steel-erection disputes are among the most expensive on a job — the average construction dispute in North America runs into the tens of millions, and geometry nobody measured is a routine root cause.
Coverage
Every steel check, and the sensor that makes it
| Inspection | What is verified | Sensor |
|---|---|---|
| Anchor bolt layout | Bolt pattern, spacing, bolt-circle and projection before steel arrives | LiDAR + RGB |
| Base plate setting | Plate elevation, level, grout pack and shim stacks | LiDAR |
| Column plumb | Lean per column over its full height | LiDAR plumb plane |
| Bay dimensions | Column-to-column spacing against the erection plan | LiDAR tied to control |
| Beam elevations | Top-of-steel elevation at every connection | LiDAR + site control |
| Connection completeness | Bolts present and counted at each connection | High-res RGB + computer vision |
| Bolt condition | Missing, loose or unturned nuts and missing washers | High-res RGB |
| Weld coverage | Visual weld presence, length and obvious surface defects | Macro RGB |
| Bracing & moment frames | Bracing installed where the drawings call for it | RGB + plan comparison |
| Metal deck | Deck placement, side laps, bearing and puddle welds | LiDAR + RGB |
| Camber & deflection | Beam profile against the specified camber | LiDAR profile |
| Fireproofing | Spray-applied coverage and obvious thin or missing areas | RGB + thermal |
| Erection sequence | What is erected versus the sequence plan, by day | RGB progress capture |
Sample output
The frame exception list, by gridline
| Location | Checked item | Spec | Drone measured | Status |
|---|---|---|---|---|
| Col. B-4 | Plumb over 32'-0" | H/500 (¾") | 1⅜" out to the north | Fix now |
| Conn. B4-C4 | Bolt count | 8 bolts | 6 installed, 2 open holes | Fix now |
| Grid C | Anchor bolt spacing | 10" × 10" | 10" × 11⅝" | Fix now |
| Beam C4-D4 | Top of steel elevation | +42'-6" | +42'-5⅜" | Review |
| Bay D1-D2 | Column spacing | 30'-0" | 30'-1¼" | Review |
| Deck L3 | Side lap fastening | 12" O.C. | 18" O.C. over 2 sheets | Review |
| Frame A | Bracing present | HSS diagonal both bays | Both bays installed | Pass |
Illustrative report format. Every finding carries the gridline, the elevation and the image the measurement came from.
What it costs when nobody's watching
Steel gets inspected at height, or it gets inspected from the air.
389
fatal falls in U.S. construction in 2024 — 38% of construction fatalities, 95.9% falls to a lower level.
Source: BLS, Census of Fatal Occupational Injuries 2024 (released Feb 2026)
$1.3M+
average total cost of a single fatal work injury.
Source: National Safety Council, Injury Facts
52%
of total project cost overrun traces back to rework.
Source: CII, analysis of 150+ industrial construction projects
5–9%
of total project cost lost to rework typically; 20–30% on troubled jobs.
Source: CII; Dodge Data & Analytics, SmartMarket Report on Project Rework (2018)
$60.1M · 12.5 months
average construction dispute value and time to resolve — erection tolerance arguments live here.
Source: Arcadis, 2025 Global Construction Disputes Report
$15.8B / yr
industry cost of poor data and interoperability between model, shop and field.
Source: NIST GCR 04-867 / NIBS (2004) — historical baseline
Government-grade sources (BLS, OSHA, NIST/NIBS) are cited as published. Industry research (Arcadis, FMI/Autodesk, CII, NSC) is survey- and estimate-based. Vendor case studies and vendor pricing pages are labeled where used and should be read as documented examples, not industry averages.