Route processing is a state machine built around imperfect position data.
A GPS fix is only an observation. The application still has to interpret where the train is on a configured route and decide what that means operationally.
Separate position, route context and station state
Keeping these concepts separate makes the behavior easier to reason about. Position answers “where”; route context answers “where on this journey”; station state answers “what operational phase are we in”.
Derived values need consistent time and distance models
Speed, average speed, distance and ETA should be computed from coherent data and validated against realistic movement—not just the most recent raw point.
Startup and recovery matter
A production system may start mid-route or temporarily lose position. Good design can rebuild useful context instead of assuming the journey always begins at station one.
Detect inconsistent progression
Movement trends can help identify when the observed direction does not match expected route progression. Exact thresholds and algorithms remain implementation-specific.
This article intentionally discusses engineering concepts at a public-safe level. Customer-specific configuration, proprietary protocols, credentials, internal network topology and private source code are excluded.