This train schedule template has saved thousands of lives since its invention in the 19th century.
This simple chart (probably invented by the French railway engineer Charles Ibry) allows railway companies to easily schedule trains on a single rail-line. Most importantly it helps schedulers to avoid time-tabling two trains on the same piece of track at the same time. It can therefore help rail companies avoid disastrous head-on collisions between two speeding trains traveling on the same train line.
This train schedule when completed would show the locations of every train traveling on the Paris to Rouen and Le Havre line in one twenty-four-hour period. It would enable rail workers to see every train's departure time, the time of each train's scheduled station stops, and each train's scheduled destination arrival time.
The horizontal axis on this chart is used to denote time. You can see that the chart starts at midnight. Each vertical line represents two minutes of time and the hours of the day are displayed along the top of the axis.
The vertical axis is used to show every train station, starting at Paris at the top and ending at Le Havre (at the bottom of this axis). The stations are marked according to distance. Each horizontal line represents one kilometre of distance. The distance from Paris to Havre is 227 km in total.
To the left of the station names (on the vertical axes) an elevation chart (labeled 'Height scales for profiles') runs down the page and shows the height above sea level along the whole line from Paris to Havre.
We can schedule a train from Paris to Maisons simply by drawing a line on the map. Here the blue line shows a train journey which leaves Paris at midnight, arrives at its first stop at Batignolles at 12.10am. The train then proceeds to stop at Colombes and Houilles, before finally arriving at Maisons at 1.20am
Let's now add a second train to our schedule. This train (shown in green) leaves Paris at 12.30am, 30 minutes after the first train left Paris. This train travels faster than the first train and arrives at Maisons at 1.24am. Although leaving half an hour after the first train the second train arrives at Maisons only 4 minutes after the first train.
Our small daily service of two trains works perfectly well. However the newly appointed fat controller decides that he wants to add a new slow train, leaving Paris at 12.20am and arriving at Maisons at 1.40am.
If the lines of two separate trains touch on Ibry's chart that means those trains will crash.
As you can see our new train (the red line) is scheduled to crash into the 12.30am train from Paris (the green line) at 12.38am 4 km after leaving Paris.
This is one of the main advantages of Charles Ibry's schedule format. It allows railway engineers to immediately spot potentail train collisions when they add a train to the schedule. The line of the scheduled train on the timetable must not cross the line of any other train. If it does then those trains will crash at the time and location shown by the horizontal and vertical axes.
Chemins de Fer is owned by the Bibliothèque nationale de France. The Chemins de Fer can also be viewed in detail on the Bibliothèque's website. You can also view a completed chart of the Paris to Boulogne line on the bibliothèque's website.
You can learn more about how this presentation was made at Maps Mania.
Charles Ibry's timetabling graph is discussed in Hannah Fry's BBC Podcast This Train has Been Delayed (Part of Hannah Fry's Uncharted series). This Train is Delayed discusses how Ibry's graph helped Singapore's transit network finally discover a glitch which was causing their driverless trains to seemingly stop at random between stations, when they weren't meant to.