From reception to operating picture
StraitWatch combines overlapping observations into a single track for each vessel. Automated checks remove duplicate or implausible reports before positions and movement states appear on the dashboard.
Receive
Collect terrestrial and satellite AIS messages, environmental observations, and navigational notices.
Normalize
Standardize timestamps, identifiers, coordinates, speed, course, vessel type, and destination fields.
Resolve
Match reports by MMSI and IMO number, then reconcile overlapping satellite and shore-based observations.
Validate
Flag stale, duplicate, out-of-sequence, or physically implausible positions before publication.
Counting a transit
A transit is recorded when a resolved vessel track crosses the monitored passage gate in a consistent direction. Multiple position reports from the same passage count once; reversals and movements that remain inside anchorage areas are excluded.
Daily total
Completed eastbound and westbound gate crossings during the preceding rolling 24-hour period.
Prewar baseline
The mean daily transit count across the defined 90-day comparison window before the reference disruption.
Direction
Assigned from the sustained course of the resolved track through the traffic separation scheme.
Coverage control
Periods with insufficient reception are marked incomplete and excluded from baseline comparisons.
Dashboard measures
Each headline measure uses a consistent operational definition so that changes over time reflect vessel behavior rather than labeling changes.
Vessels tracked now
Unique vessel tracks with a validated report inside the coverage area during the active freshness window.
In transit
Tracks moving through the monitored passage corridor with a sustained speed and directional course.
Waiting / anchored
Tracks inside designated waiting or anchorage areas with low speed over ground or a stationary pattern.
Signal coverage
The share of expected monitoring intervals containing at least one usable observation from the feed network.
Assessment confidence
Confidence reflects source agreement, signal recency, coverage continuity, and the amount of corroborating evidence behind an operational judgment.
Multiple current sources agree, coverage is continuous, and no material contradictions remain unresolved.
The assessment is supported, but one source is delayed, coverage is uneven, or a limited inconsistency remains.
Evidence is sparse, stale, or contradictory. The dashboard treats the conclusion as provisional.
What the picture cannot guarantee
AIS is a cooperative reporting system. Transmissions can be delayed, incomplete, incorrectly entered, switched off, or affected by interference. Satellite reception also introduces latency, and classifications may change as better identity information arrives.