Quick answer: a scheduled arrival is the time a bus or train is planned to reach a stop. A real-time arrival is a prediction updated from current operations, such as a vehicle position, delay report or dispatcher change. Trust a real-time estimate only after confirming the correct stop, direction and trip, checking when the information was updated, and reading any service alert. If live data disappears or stops changing, fall back to the timetable cautiously and verify with the operator.
A screen that says “5 min” feels precise, but it is still a forecast. The vehicle may be moving through traffic, waiting to begin its route, held by a dispatcher or represented by incomplete data. Meanwhile, a clock time such as “08:42” may be either a timetable entry or a live prediction depending on the app. Learning the difference prevents two common mistakes: arriving too late because a bus came earlier than expected, and waiting indefinitely for a trip that is no longer operating.
This guide applies worldwide. Transit systems label information differently, so use the operator’s legend and official alerts as the final authority.
The three types of time you may see
Scheduled time
A scheduled time comes from the published timetable. It describes the service the operator intends to run for a particular date, route, direction and stop. It does not prove that the vehicle is currently operating or on time.
Schedules are essential for planning future journeys, checking first and last services and understanding normal frequency. Transport for New South Wales explicitly notes that ordinary timetables do not include real-time information, short-term changes or disruption alerts. That distinction is useful everywhere: a timetable is the baseline, not a live status report.
Estimated or predicted time
An estimated arrival combines the schedule with current information. The prediction may use a vehicle’s location, progress along the route, traffic, historical running times or an operational update. The General Transit Feed Specification (GTFS) describes trip updates as predicted arrivals or departures that represent changes from the timetable.
Some apps display a countdown—“6 min”—while others replace the scheduled clock time with an updated one. Look for visual labels such as “live,” “real-time,” “estimated,” a vehicle icon, pulsing marker or distinct color. The exact symbol is local.
Observed or actual time
An observed time records something that already happened, such as a vehicle passing a stop. It may appear in operational tools or journey history rather than the passenger countdown. Do not confuse a map dot with an arrival prediction: location is an observation, while time-to-stop is a calculation.
Where real-time transit information comes from
Many agencies publish data that journey planners and apps transform into passenger information. GTFS separates static schedules from GTFS Realtime. The real-time side can include:
- Trip updates: predicted stop times, delays, cancellations, added trips or reroutes;
- Vehicle positions: a vehicle’s reported location and, optionally, direction, speed or timestamp;
- Service alerts: disruptions affecting a trip, route, stop, station or network; and
- Trip modifications: structured changes such as detours or skipped stops.
Not every operator provides every type. A bus may have a live position but no reliable prediction for later stops. A train may show a dispatcher-supplied delay without a public map position. A third-party app can only interpret the feeds and other sources it receives.
Transport for London says its live bus-arrival interface provides predictions for upcoming buses and refreshes frequently. Transport for NSW offers real-time departures and live vehicle information in its planner. Washington’s WMATA developer portal distinguishes train arrivals, bus predictions and schedules. Different networks, same principle: “live” information is a layer placed over the planned service.
How to tell whether an arrival is scheduled or real-time
Start with the app or display legend. Then check five clues:
- Label: look for “scheduled,” “timetable,” “estimated,” “predicted,” “live” or “real-time.”
- Symbol: a radio-wave, satellite, vehicle or pulsing icon often indicates live data.
- Update behavior: a prediction should normally change as the vehicle moves or conditions change.
- Vehicle marker: a mapped vehicle may support the estimate, provided its position timestamp is recent.
- Fallback styling: some apps switch to a lighter color, plain clock or timetable icon when live data is unavailable.
Never assume that a countdown is automatically live. An app can calculate “12 minutes” simply by subtracting the current time from the timetable. Conversely, a clock time can be a real-time prediction. The operator’s help page or legend matters more than the display format.
Verify the stop, direction and trip before trusting the number
An accurate prediction for the wrong stop is useless. Stops on opposite sides of a road may share a name. A station can have separate platforms for branches or express services. Large interchanges may contain several bus bays.
Confirm:
- stop ID, platform or bay;
- route number or line name;
- destination or travel direction;
- express, limited-stop or local pattern;
- service date when traveling after midnight; and
- whether your destination is served by this particular trip.
Transport for NSW promotes stop IDs and stop-specific QR codes precisely because a unique stop is more reliable than a familiar-looking name. If you are assembling the full journey, our step-by-step public transport planning guide explains how to verify every leg and transfer.
Check how fresh the data is
A vehicle position includes or can include a timestamp for when the location was recorded. That is different from the time an app fetched the feed. If the vehicle last reported several minutes ago, the dot may be frozen while the prediction continues to count down.
Warning signs of stale information include:
- the map marker does not move across several refreshes;
- “last updated” becomes increasingly old;
- the countdown reaches zero and resets upward;
- several vehicles occupy exactly the same location;
- the app shows live data but the official alert reports a suspension; or
- one app changes while every official channel remains static.
Refresh once, then compare the official stop display, operator app or status page. Repeatedly refreshing cannot create data that the vehicle is not transmitting.
Why a predicted arrival moves backward or forward
A prediction may change because the vehicle encounters traffic, spends longer at a busy stop, receives priority, changes drivers, waits to regulate spacing or is reassigned. Downstream estimates can also change when an earlier vehicle begins a new trip.
Prediction uncertainty is usually greater farther from the stop. A bus that is 35 minutes away has more opportunities to meet traffic than one visible around the corner. Treat distant estimates as planning guidance and near-term estimates as stronger—but never perfect—evidence.
For an important connection, do not plan to arrive at the exact predicted departure time. Leave a buffer and use the principles in our guide to choosing enough time between train connections.
What it means when a vehicle disappears
A missing prediction does not have one universal meaning. The trip may be cancelled, the tracking equipment may have stopped reporting, the vehicle may have changed identifiers, or the app may have lost the data feed. GTFS guidance is explicit that the absence of a trip update should not automatically be interpreted as the trip running on time.
Use this response:
- check the official service alert for cancellation, detour or stop closure;
- confirm that you still have the correct stop and direction;
- compare the operator app or station display with one other source;
- look for the next scheduled trip as a fallback, not a guarantee; and
- set a personal decision time for waiting versus rerouting.
If the route is disrupted, follow our public transport disruption playbook rather than chasing a disappearing countdown.
How to travel when only scheduled times are available
Scheduled-only information is normal on smaller systems, rural routes and services without tracking. Arrive before the published departure, because local rules may permit an early pass at intermediate stops or define times as approximate. At a timed-transfer point or origin, the timetable may be more tightly controlled.
Check whether the timetable marks:
- exact or approximate times;
- request stops;
- school-day, weekday, weekend or holiday variants;
- short trips that terminate early;
- footnotes applying only to selected journeys; and
- frequency bands such as “every 10–15 minutes.”
Use the route map to confirm the direction and stay visible at the stop. If boarding is by request, signal according to local practice. Save the operator’s contact or alert page before entering an area with poor connectivity.
How to read frequency-based service
Some high-frequency networks publish intervals rather than exact times. “Every 8 minutes” describes an intended average gap, not a promise that a vehicle will arrive eight minutes after you reach the stop. Congestion and uneven passenger loads can cause bunching: two vehicles arrive together, followed by a longer wait.
When live positions are available, compare the first two vehicles rather than focusing only on the first. A packed bus one minute away may be followed by a quieter one in four minutes. However, do not let a close prediction tempt you into an unsafe road crossing or platform rush.
Read service alerts before optimizing the arrival time
A perfect arrival prediction does not tell you whether the vehicle will serve your destination. An alert may report a detour, skipped stop, partial closure, elevator outage or modified platform. GTFS treats service alerts separately from trip updates because the two answer different questions:
- Prediction: when might this vehicle reach the stop?
- Alert: what has changed about the service or its usability?
Check alerts first whenever the app shows a warning badge. For an accessible journey, an elevator or boarding change can matter more than a two-minute delay. Revalidate the complete path with our accessible transit journey checklist.
Which source should you trust when apps disagree?
Use a source hierarchy:
- safety instructions and staff at your location;
- the operator’s official alert and stop display;
- the official journey planner or app;
- a third-party planner for comparison; and
- social posts as unverified clues.
Two third-party apps can receive the same agency data but refresh, filter or model it differently. A difference does not automatically mean either is dishonest. Check timestamps, vehicle identity and the official disruption status.
A 30-second arrival-time checklist
- Correct stop, platform and direction
- Correct route, destination and stopping pattern
- Scheduled or real-time label identified
- Update timestamp recent
- Vehicle marker moving, if available
- Service alerts checked
- Next option identified if the trip disappears
- Personal wait-versus-reroute deadline set
Frequently asked questions
Are real-time transit arrivals always accurate?
No. They are predictions based on available operational data. Accuracy can change with distance, traffic, stale vehicle positions, dispatch decisions and data outages.
Does “scheduled” mean the vehicle is on time?
No. It means the time comes from the timetable. If no live update exists, you should not assume that the trip is operating normally.
Why did the countdown reach zero without a bus or train?
The vehicle may be delayed, the location may be stale, the stop may have moved, or the app may have reverted to timetable math. Check the official alert, stop identity and update timestamp.
Is a vehicle shown on the map definitely in service?
Not necessarily. A position can be old or attached to a vehicle that is not boarding passengers. Confirm the trip, direction and freshness of the position.
Which app has the best real-time information?
The answer varies by network. Start with the official operator’s tools, then compare reputable apps that disclose live-versus-scheduled labels and update times.
The practical takeaway
Scheduled and real-time transit arrivals answer different questions. The schedule tells you what should happen; the prediction estimates what is happening now. Use both, but verify the stop, direction, data freshness and alerts before acting. A live countdown is valuable evidence—not a guarantee—and a missing prediction is not proof that the vehicle is on time.
Official sources and further reading
- GTFS: scheduled and real-time transit data overview
- GTFS Realtime: trip updates and predicted stop times
- GTFS Realtime: vehicle positions and timestamps
- GTFS Realtime: service alerts and affected entities
- Transport for London: live bus-arrival data
- Transport for New South Wales: timetables versus live information
- WMATA: train arrivals, bus predictions and schedules