CASE C23 · US · 2018
NJDOT: cost comparison of drone inspection for 244 high-mast light poles at highway interchanges
In 2018 NJDOT compared the cost of drone inspection for 244 high-mast light poles at highway interchanges. Drones were far cheaper than bucket-truck inspection of every pole, but their direct cost was higher than the current ground-based method. They came out slightly ahead only after avoided lane closures were given a monetary value.
| Owner | New Jersey Department of Transportation (NJDOT) |
| Provider | Cambridge Systematics (research contractor) |
| Location | New Jersey, United States |
| Aircraft | UAS (model not named) |
| Sensors | HD video, 20 MP stills |
Before
Two engineers inspect from the ground with binoculars; about 10% of poles get a bucket-truck follow-up, sometimes needing shoulder/lane closures. Historically every pole was inspected by bucket truck.
With drones
A pilot plus two engineers image each pole by drone, with close stills of suspected defects; base, anchor bolts and luminaires are still checked by other means.
Outcomes
| Metric | Value | Basis |
|---|---|---|
| labour-hours per cycle | UAS 1,476 vs traditional 1,264–1,552 vs bucket truck (all poles) 3,312 | Estimate |
| direct cost per cycle | UAS $186,025 vs traditional $167,600–177,667 vs bucket truck $477,022 | Estimate |
| total cost incl. safety and efficiency | UAS $186,025 vs traditional $190,988–201,055 | Estimate |
Caveats & limits
- On direct cost the drone was more expensive than the ground-based traditional method; it came out ahead only after monetising avoided closures and follow-up trips.
- Six of 244 poles could not be flown (ground cover, airspace, or need to cross live traffic, which NJDOT does not allow).
- Savings depend on an assumed 10% defect rate; the report's efficiency figure is internally inconsistent ($1,736 vs $1,666 per pole).
- Desk-based cost model from a research study, not a multi-year operational record.
Sources
- High Mast Drone Inspection (Report NJ-2018-003)New Jersey DOT Bureau of Research / USDOT ROSA P Full text read
Sources checked: 2026-10-22