How to read the Bulletin

The Bulletin looks at where buses, trams and urban trains really are, every few seconds, and compares it with the official timetable. From that it works out how many runs there were, how long people waited at the stops, where vehicles slow down and when they travel in pairs. A five-minute read.

1 · The basics

Where the data come from

Transit companies publish two streams of open data: the timetable (GTFS), with every scheduled trip, and the real-time positions of their vehicles (GTFS-Realtime). A server collects the positions day and night; every night it matches them to the lines' routes and turns them into passes at the stops.

This page downloads those summaries (the last two weeks) and does all the arithmetic in your browser. No sign-up, and nothing leaves your computer.

2 · The first page

The bulletin of the day

At the top you choose the day (today too, updated every half hour or with «update today too»). The headline sums the day up in one sentence; below it, the figures for the whole network:

Runs madeHow many of the passes the timetable promises at a checkpoint (halfway along the line) actually happened.

Average wait at the stopHow long someone waits who turns up without checking the timetable, compared with the wait «if regular»: why they differ.

Passes in pairsVehicles arriving almost on top of the one before: two together, then a gap.

Vehicles in serviceHow many vehicles were really running at rush hour, against how many the timetable needs.

SpeedCommercial speed, stops included, terminals excluded.

Longest gapBetween 7am and 8pm, the biggest gap relative to the interval scheduled at that time: «3×» means three times the promised wait (30 minutes where the timetable said 10).

Then the ranking of the lines, worst first: click a row to open its page. Click a column heading to re-sort. The ⓘ symbols explain every number.

3 · The key idea

Frequency and wait are not the same thing

If a vehicle comes every 6 minutes, someone arriving at random waits 3 minutes on average: but only if the vehicles are evenly spaced. With the same vehicles per hour arriving in pairs, the wait grows: whoever arrives almost always lands in a long gap.

Each triangle is an interval between two vehicles: its height is how long someone arriving at that moment waits, its area is everyone's wait. Here nine people in ten arrive during a 10–11 minute gap.

That is why the Bulletin always shows the real wait next to the wait «if regular»: the difference is the price of irregularity, which counting the runs made cannot see.

4 · One line

A line's page

It opens when you click a line in any ranking. From top to bottom:

The line's figures and the rush hours: runs, wait, pairs, speed, compared with the average.
The last ten days at rush hour: wait and speed day by day. Hovering over a number shows how it went hour by hour that day.
Hour by hour: runs made and missed, with the historical forecast.
The longest waits and exceptional events (line blocked, a vehicle leaving service halfway along the line).
The space-time diagram and the spiral, explained below, with a replay of the day (▶ Start) and the map of the vehicles.
The stops of the line, in both directions: click one for its page.
Where time is lost: the 200 m stretches where the line runs slower than its usual pace, with an estimate of what that costs in a year.

5 · The main chart

The space-time diagram

Time runs across, position along the line runs up, from one terminal to the other. Each coloured line is a vehicle: blue in one direction, orange in the other.

Steep: the vehicle is moving fast. Flat: it is standing still (stop, traffic light, queue).
Lines evenly spaced: regular service.
Two lines touching: vehicles in a pair, and a gap ahead of them.
The spaces between one vehicle and the next are coloured by how long people wait there: the warmer the colour, the longer the wait.

Drag to choose the period; click a vehicle to highlight it, a stop to see its passes.

On the left, regular vehicles. On the right a vehicle stands still halfway: a gap opens ahead of it, the next one catches up and at the following stops they arrive together.

6 · Another way of looking

The spiral

The same diagram rolled up: time grows outwards and one full turn is a trip out and back (for circular lines, one lap of the line). The vehicles go round like clock hands, and bunches show up as crowded slices followed by empty ones.

Wheel with Ctrl (or ⌘), or two fingers: zooms without changing the period.
+ and − in the centre and on the rim: change the start and end time.
Measure: drag between two points to read the time elapsed (it snaps to stops and vehicles).
Hovering over an interval shows how long people waited there.

7 · The other tabs

The other pages

Period reportThe same measures over several days together, to see the trends.

Junctions and signalsWhere the network loses most time at traffic lights and junctions, on a map.

LinesAll the lines in one table, searchable by number.

StopsEvery stop has its own page: the lines that call there, the runs made and scheduled, the longest waits. You get there from the search, from the list of stops on a line's page, or from the ↗ sign next to the names in the diagrams.

FleetHow many vehicles of each series are in service, and when during the day.

Every vehicleClick a vehicle’s number (in the Fleet or on a line’s page): what it did over the last ten days, on which lines, how many kilometres, and its day hour by hour.

JourneyTwo clicks on the map: how long it should take according to the timetable and how long it really took on past days.

How the lines are doing nowThe simple page for your phone: the state of the lines right now, the vehicles on the map, how to get there.

8 · Honesty

Limits

A «missed» pass may be a vehicle without a signal, not necessarily a trip not run: the Bulletin flags it when data coverage is low.
The causes of delays (traffic light, queue, doors, breakdown) cannot be seen from the positions: they are inferred from the place and the moment.
The average wait assumes people arrive at the stop without checking the timetable, as they do on frequent lines.
Days with little data are marked as such; forecasts get better with at least two weeks of history.

Every line and every stop has its own address: the one in the browser bar can be copied and sent, and reopens the same page (with the same day).

This is an independent analysis of open data: it is not a service of the transit companies, which remain the official source for timetables and notices.