About Trackside

Every reliability figure on this site is built from the agency’s own realtime feed, recorded continuously — a record of how each train actually ran, not a promise about how it “should” run.

How we measure delay

Delay is measured against each train’s published timetable — the same schedule the agency prints for riders. We record each train’s real-time position continuously and log how it actually arrived against that schedule, stop by stop.

What “on time” means

A train arriving within 2 minutes of its scheduled time counts as on time here. A minute or two of variance is noise, not lateness, so a train that’s consistently a minute early or late reads as “usually on time” — the way a rider would actually describe it — rather than technically late by a few seconds.

Many transit agencies count a train as on time if it arrives within about five or six minutes, so the figures here — measured to the 2-minute mark — read a little stricter than an agency’s own headline number.

Counted at every stop

An on-time percentage here counts every stop a train makes along its route — not just whether it reached its final destination on time. A train that runs late through the middle of its trip counts as late at each of those stops, even if it makes up the time and arrives at the end on schedule. This reflects the ride riders actually experience: a stop that was late was late, wherever it fell on the line. We leave out each train’s starting terminal, where it is departing rather than arriving, and count its arrival at every stop after that.

Arrival at the final stop

At a train’s last stop, the realtime feed’s reported arrival can run a few minutes later than the train physically reaches the platform — the feed tends to hold a cushioned estimate through the slow final approach into a busy terminal. So rather than take that estimate at face value, we use the train’s own recorded position to log when it actually arrived. It means a train’s arrival at its destination reads as the moment it really got there, not a padded one — the number a rider standing on the platform would recognize.

Recent trips count more

A train’s reliability figure is not a flat average of every day on record. Recent service is weighted more heavily than older service, so the numbers track how a train is running now rather than being anchored to how it ran earlier in the record. Older days still contribute, but their weight fades gradually over time.

When a schedule changes

When the agency retimes a train — moving its scheduled arrival at a stop — what “on time” means at that stop changes with it. Rather than blend the old and new schedules into one misleading average, we measure against the schedule in force and restart the record for that stop at the change. So a train’s figures always reflect its current timetable, not a schedule it no longer runs. A routine feed republish that does not actually move a train leaves its history intact.

Confidence & sample size

Most figures here are built from enough days of service to report a precise on-time percentage, so we lead with that number and leave the day count off — it is provenance, not something a rider needs to weigh a train by. When a train has fewer than 8 recorded days, we say so directly — a “based on N days — early data” caveat in place of a precise percentage, because a handful of trips can only land on a few coarse numbers and presenting that as a confident percentage would be false precision. Weekend service in particular tends to carry fewer recorded days than weekdays, simply because there are fewer trains and fewer Saturdays and Sundays in the observation window.

Disclaimers

• Trackside is an independent project — not affiliated with or endorsed by MARC, the Maryland Transit Administration, Amtrak, CSX, Alstom, or VRE.
• All schedules, route names, and trademarks belong to their respective transit agencies.
• The reliability figures here are unofficial, compiled by Trackside from public realtime feeds, and provided as-is, with no guarantee of accuracy.
• Do not rely on Trackside to catch a train or to make safety-critical decisions — always confirm with the agency’s official schedule and alerts.

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