Observed data stays observed. Predictions stay predictions.

Fort Madison Live is built around provenance. Every event is internally classified as observed, official, scheduled, estimated, inferred, historical or unavailable. The interface must never turn model output into an apparent railroad or bridge-operator fact.

River

Current river data uses NOAA/NWS National Water Prediction Service gauge FMDI4. Observations are provisional. The original USACE gauge is located at the Fort Madison bridge and reports an elevation-style stage near the 528 ft flood threshold, so it should not be confused with conventional lower-number stage readings at other Mississippi River gauges.

Commercial tows

USACE Lock Performance Monitoring System records from Locks 18 and 19 can identify the vessel, direction and number of barges. A recent lockage becomes a candidate Fort Madison movement only when its travel direction is toward the bridge. Initial travel windows are deliberately broad until enough Fort Madison ground truth is accumulated.

Passenger rail

Southwest Chief #3 and #4 are exact passenger-train identities. A configured live provider can supply current location and delay. Without one, the interface uses the official published timetable and labels the result SCHEDULED.

Freight rail

No public BNSF GPS feed is assumed. Freight is published as an identified train only when a licensed commercial provider or authorized partner supplies an observation. The adapter accepts physical identity such as carrier + locomotive + direction, which is more useful and safer than guessing an internal train symbol.

Bridge interaction

The engine compares a train's arrival interval with a tow's modeled bridge-unavailable interval. An overlap is described as a likely interaction, never as a claim that BNSF dispatch has stopped a particular train.

Release standard

Wrong identity is treated as a more serious error than missing identity. “Identity resolving” or “provider unavailable” is preferable to manufactured precision.