How we measure reliability.
Every number here is derived from the same real-time feeds the agency publishes — scored against ground truth we reconstruct ourselves. No schedules taken at face value, no agency-supplied grades. This is what the data actually shows.
Expected wait the headline
The single most honest number for a rider: how long you actually wait at a stop you arrive at randomly, once buses bunch and gaps open up. It is not half the scheduled headway — irregularity makes the real wait longer.
Where h̄ is the mean headway (time between buses) and CV is its coefficient of variation — the random-incidence wait. A perfectly even route waits half a headway; a bunched one waits much more.
The metrics
- Mean headwayAverage observed time between consecutive buses on a stop, per direction.
- Headway regularityCoefficient of variation of headways. Lower is steadier; high values mean bunching and long gaps.
- On-timeShare of arrivals within a window of schedule — 1 minute early to 5 minutes late.
- Schedule deviationMedian minutes off schedule. Positive means running late.
- Detour rateShare of trips that left their scheduled path — surfaced, not hidden.
- GradeAn A–F letter summarizing punctuality, calibrated to the realistic range of urban-bus on-time performance: a C is a median DC route, an A is genuinely strong, an F is the real bottom. An absolute scale, not a curve — we don't grade on a curve any more than we'd let an agency. Expected wait is still the headline number.
- TrendThe arrow by a grade is week-over-week: average on-time over the last 7 days vs the 7 before. ↑ improving, ↓ declining, → steady (small swings are treated as steady, not noise). We compare full weeks so day-of-week differences cancel out, and we show nothing until there's enough history to be honest — no arrow on a route we've only watched a few days.
Our forecast vs the agency's the moat
On each route detail page we publish our arrival predictions head-to-head against WMATA's own TripUpdates feed, both scored against the same ground-truth arrivals we derive. We hold ourselves to the same bar we hold the agency. Where we're more accurate, we say so; where we're not yet, the number shows it.
Where the data comes from
Vehicle positions, trip updates, and schedules are read continuously from WMATA's public GTFS and GTFS-Realtime feeds. Arrivals are reconstructed by map-matching each bus to its route geometry. Routes with too little data to score honestly are left ungraded rather than guessed.
Independent · derived from GTFS-Realtime · not affiliated with WMATA.