How our bus information works

Where the data comes from

The main source is the Department for Transport’s Bus Open Data Service, usually shortened to BODS.

BODS makes timetable, route, fare and vehicle-location information published by bus operators available as open data. We currently use the timetable and vehicle-location parts of that service.

Data freshness

These times show when this website last completed a successful refresh of each type of public information. They do not necessarily represent the time of the operator’s most recent change.

A missing time does not prevent the map or departure boards from working. It usually means the relevant information has not completed its first refresh since freshness reporting was enabled.

Timetables, routes and stops

Published timetable data describes routes, stops, trips, service calendars, stop sequences and scheduled departure times. We import this into local GTFS-style tables used by the website.

This gives us the planned order of stops for each individual trip, rather than assuming that every journey on a route follows exactly the same pattern. This matters because a route may have:

• different directions;
• branches and alternative route patterns;
• short workings that terminate before the usual final stop;
• school-day or event-specific journeys;
• different weekday, weekend and bank-holiday schedules.

Route lines shown on the map are generated from the published route shapes. Where a route has several legitimate variants, the map can display more than one shape.

Live vehicle positions

Vehicle positions are obtained from the BODS SIRI-VM feed. SIRI-VM is a standard format for sharing automatic vehicle-location information between transport systems.

A live record can contain information such as:

• the vehicle reference;
• the advertised route number;
• its latest latitude and longitude;
• the time that position was recorded;
• its origin and destination references;
• a journey reference and direction;
• an optional bearing.

A position is the latest observation received from the vehicle. It is not necessarily its exact location at the moment the map is viewed. Feed, network and processing delays can all make a marker appear behind the real bus.

Why an operator’s app may be ahead

There is an extra hand-off between a bus reporting its position and that position reaching this website. Operators and their tracking suppliers may have access to their own lower-latency vehicle tracking systems. The public copy has to be published through BODS and then collected and processed by us, so it can be a little older by the time it reaches the map or a departure board.

That means an operator’s own app, control room or stop display may sometimes show a bus a few seconds further along the road, or update an arrival before we do. We cannot see the operator’s private live feed; we can only work with the latest public BODS observation we have received. Our prediction code can estimate movement between observations, but it cannot turn an older observation into a truly instant location.

How we match a vehicle to its journey

A location alone is not enough to identify a journey. Two buses may be close together, travelling in opposite directions, or serving different branches of the same route.

We therefore compare several pieces of information, including:

1. An exact published journey reference, when it corresponds to an imported timetable trip.
2. The route number and the ordered origin and destination stops.
3. Whether the timetable service is active on the relevant date.
4. The vehicle’s location compared with stops on the candidate trip.
5. The timetable time at nearby stops compared with the time of the vehicle observation.
6. The trip direction and ordered progress along the published route shape.

If the evidence is not strong enough, we prefer not to claim that a vehicle serves a particular stop. This may mean that a genuine bus is temporarily absent rather than shown on the wrong side of the road or against the wrong journey.

Non-public and special journeys

Live feeds can occasionally contain school-only, positioning or otherwise non-public journeys using a familiar route number. Confirmed examples can be excluded using their exact route, origin and destination references. We do not broadly hide every journey that mentions a school, because many ordinary public services legitimately serve schools and colleges.

How departure predictions are calculated

The timetable is our starting point, but a live bus is rarely running exactly to it. When a recent vehicle position can be matched to a particular journey, we use that journey’s stop order and route shape to work out how far the bus has actually got.

We then compare its observed progress with where the timetable says it should be. Stops that the bus has already passed are removed, and the remaining times are adjusted from that live position.

Recent movement

When the bus is reasonably close to a stop, we can also use its recent movement to improve the estimate. We look at several recent observations rather than trusting a single GPS jump, and ignore readings that are stale or imply an unrealistic speed.

This is most useful over the last part of a journey to a stop, where the timetable alone cannot tell us whether the bus is moving freely, crawling in traffic or waiting at lights.

What previous buses tell us

We keep recent observations of how long buses actually took to travel between neighbouring stops. Where there is enough good data, we use journeys from a similar day and time of day to help estimate the road ahead. A weekday morning, for example, is treated differently from a quiet Sunday afternoon.

For each section we use the middle of the recent observations rather than a simple average. That makes the result less likely to be thrown off by one unusually slow journey, a long wait at a stop or a bad location reading. Samples that do not meet the quality checks are not used.

These historical timings do not take over from the live position. They are a limited adjustment to the live estimate. If there is not enough reliable history for part of the route, the published timetable is still used for that section.

In practice a live time can therefore use several pieces of evidence at once: the timetable, the bus’s current position, its recent movement and, where there is enough evidence, recent real-world travel times over the road ahead. The balance changes as the bus gets closer.

Predictions are recalculated regularly and cached briefly so every visitor does not have to process the complete live feed separately. The displayed time is still an estimate rather than a guarantee that the bus will arrive at that exact minute.

What “Live” and “Scheduled” mean

“Scheduled” does not necessarily mean that the bus is cancelled or not running. It only means that this website cannot currently attach a reliable live observation to that departure.

How the map works

The browser uses MapLibre to display route lines, stops and vehicle markers over OpenStreetMap-based mapping.

Static information—such as stops and route shapes—is generated periodically and served as GeoJSON. Frequently changing vehicle and departure information is prepared by a background task and stored in a short-lived cache.

Between live observations, a marker may be moved along the matched route shape to make movement easier to follow. We limit how far a position can be corrected. If an observation is too far away from the expected route, the site avoids drawing an invented straight line across buildings or unrelated roads.

When a bus marker is selected, its popup uses the matched trip’s remaining ordered stops. Passenger-facing destinations prefer a curated route mapping where one is available, followed by the matched trip’s final stop. Timetable and live-feed names are used only as fallbacks. This keeps ordinary termini consistent while still preserving branches and short workings.

Further information

• Find and use bus open data — GOV.UK
• SIRI-VM technical guidance — GOV.UK
• OpenStreetMap copyright and attribution
• Return to the live bus map