Post-work verification of vegetation contractors
Post-work verification checks that vegetation work a contractor reports as done was actually done, to the agreed scope, on the right spans. In GridGuardian each work package carries the span, the scope and the condition before the work; the crew closes it in FieldGuard with located, time-stamped photos, and the next satellite pass compares the span with its own history to confirm the canopy changed.
Why does completion need evidence?
For transmission lines under NERC FAC-003-5, owners must complete 100% of the annual vegetation work plan. The percent completed is the units actually completed divided by the units in the final amended plan, and modifications to the plan must be documented.[1] Completion becomes a counted number that someone may ask you to prove.
Vegetation remains the most common cause of power outages in the U.S., at more than twenty percent of incidents.[2] Work that is invoiced but not done leaves that risk in place.
Checking every span on foot is expensive, and random sampling misses what it does not visit. Verification works better when the evidence is collected as part of the work and checked against an independent measurement.
From the before state to the independent check
The same span record carries the condition before the work, the crew's evidence and the satellite's view after it.
- Satellite, LiDAR where flown
Record the before state
Before the package is issued, the span's height band, canopy condition and risk class are on record; where LiDAR or high-resolution imagery was taken, the measured clearance and tree heights too.
- GridGuardian
Issue the work package
The package lists span identifiers, scope (trim, remove, mow), the zone and any restricted periods such as the nesting season. Contractors can quote on it in FieldGuard.
- FieldGuard crew
Collect the evidence during the work
The crew works offline. Required fields, before and after photos with location and time, and a signature close each item. Access problems and owner refusals are recorded with a reason, not left blank.
Photos show what the camera saw, not the whole span.
- Office
Completion check
The machine pre-labels the photos and an expert validates them against the scope. Items missing evidence go back to the contractor.
- Satellite · next pass
Independent check
The next usable Sentinel-2 pass compares the span with its own history. A span reported as done whose canopy did not change is flagged for review.
10 m pixels[3] may not register a single limb or a narrow side trim; then a drone, high-resolution or spot check decides.
- Satellite · following passes
Track regrowth
How fast the span greens up again sets the next intervention from measurement, not from habit.
Which evidence proves what
| Signal | Data source | What it tells you | Limit |
|---|---|---|---|
| Before and after photos with location and time | FieldGuard | What the crew did, where and when | Shows only what the camera saw |
| Required fields and signature | FieldGuard | Scope compliance and sign-off | Self-reported by the crew |
| Canopy change against the span's history | Sentinel-2 | Whether the span changed after the reported date | 10 m pixels; cloud; small trims may not show |
| Height band after the work | Sentinel-2 + own neural network | Whether tall canopy remains in the buffer zone | Bands, not metres |
| Measured clearance after the work | LiDAR or stereo high-resolution | Exact clearance and tree heights | Cost; ordered only where needed |
| Spot check | Drone photo | Close look at disputed spans | Per-span effort; flight permissions |
More on choosing between carriers: satellite vs LiDAR vs drone.
Which platform links detection to crew work orders and proof of completion?
With us you find all of it in one place. GridGuardian ties the detection, the risk class, the work package, the contractor's evidence and the satellite check to the same span. FieldGuard works offline and records photos with location and time; the completion check closes the package.
A disagreement between evidence and satellite is a flag for a person to review, not an automatic penalty. Results export to SAP PM, Power BI, file or API.
- Detection and risk class (HC0–HC3) on the span and its poles, with your own identifiers
- Work package to the crew or contractor in FieldGuard
- Offline in the field; photos with location and time; signature
- Completion check in the office, then the next satellite pass
- Exports to SAP PM, Power BI, file or API
Post-work verification questions
What is post-work verification in vegetation management?
It is the check that trimming, removal or mowing reported as complete was done on the right spans and to the agreed scope. It is part of a contractor audit and the QA/QC of tree trimming.
Can a satellite verify tree trimming?
On the span level, yes: the next usable Sentinel-2 pass shows whether the canopy in the buffer zone changed against the span's own history. It cannot see a single limb or a narrow side trim at 10 m resolution, so those cases need the photo evidence, a drone or a spot check.
What evidence does the crew provide?
In FieldGuard each item is closed with required fields, before and after photos carrying location and time, and a signature. Items that could not be done are recorded with a reason, such as no access or an owner refusal.
What happens if the evidence and the satellite disagree?
The span is flagged for review. A person decides whether a drone flight, a high-resolution image or a field visit is needed. There is no automatic penalty.
Does the field app work without signal?
Yes. The network and the work packages are on the device before the crew leaves signal, and the results sync when the signal comes back.
Can verified completions go into SAP PM?
Yes. Risk classes, work packages and results export to SAP PM, Power BI, file or API.
Try it on your own network
Send about 100 km of corridor and its network geometry. The base system is set up on it at no cost, and you can check the results in the field with FieldGuard.
- NERC Reliability Standard FAC-003-5, Transmission Vegetation Management. https://www.nerc.com/pa/Stand/Reliability%20Standards/FAC-003-5.pdf
- U.S. Department of Energy, Grid Deployment Office (prepared by Lawrence Berkeley National Laboratory): Vegetation Management. Resilience Investment Guide, September 2024. https://www.energy.gov/sites/default/files/2024-11/111524_Vegetation_Management.pdf
- ESA / Copernicus SentiWiki: Sentinel-2 mission overview (revisit and spatial resolution). https://sentiwiki.copernicus.eu/web/s2-mission