Why one percentage misleads
A vehicle can drive 100% of a corridor while the camera faced the sun, rain covered the lens, or the GPS dropped out under a flyover. A reviewer may then watch only part of the footage. If all of that is reported as “96% covered”, the client cannot tell which sections were actually inspected.
The four coverage states
| State | Meaning | Typical cause of gaps |
|---|---|---|
| Travelled | The GPS track passes along the section | Wrong turn, missed section, GPS outage |
| Usable footage | Clear, in-scope video exists for the section | Night, rain, glare, camera off |
| Explicitly reviewed | A reviewer deliberately marked the range as reviewed | Review not finished |
| Observation confirmed | Findings or observations were saved for the section | No defects present, or not yet recorded |
Watching playback alone should never count as “reviewed”. In RouteLens, reviewing is a deliberate action on a range.
Dual carriageways, loops and repeat passes
Coverage matching has to be direction-aware. A divided highway has two carriageways that must each be covered; a pass in the opposite direction does not cover the other side. Loops, crossings and parallel service roads can also confuse simple distance checks. Repeat passes and overlapping recording chapters should not be counted twice.
Building the resurvey list
- Import the assigned scope as sections with IDs and direction.
- Run coverage against the recordings.
- List sections that were not travelled or have no usable footage.
- Export a gap and resurvey CSV for the field team, with section IDs and direction.
- Record reviewer exceptions, such as sections excluded by the client, in the run.
What to hand the client
A summary with the scope, exclusions, thresholds and the four totals with their definitions; a section table; the gap list; and a readable coverage report. RouteLens produces all four from a saved coverage run.
Questions
What is survey coverage?
The share of the planned survey scope that was travelled, has usable footage, was explicitly reviewed and has confirmed observations, reported per section.
Does watching the video count as reviewed?
No. Reviewed should be a deliberate reviewer action on a range, so playback alone is never counted.
How do I handle both directions of a highway?
Treat each carriageway and direction as its own scope sections and use direction-aware matching, so one direction never covers the other.
RouteLens is built by UGAC. Where this guide describes RouteLens behaviour, it reflects the release status published on 29 October 2026; see the product overview for what is verified.
