In both "The Visual Display of Quantitative Information" and "Envisioning Information" by Edward Tufte, he writes quite a bit on graphical timetables. Even the cover of "Visual Display" is a graphical timetable. You can read some extracts on the graphical timetable from the books here on his website. Below is an example created by Tufte. On the above viz, Tufte says, "My design of a bus schedule and route combines a graphical timetable with a route map overlaid on a precisely detailed aerial photograph, so much richer than the typical schematic diagram of bus routes. Hourly, daily, and weekly rhythms of the buses are clearly revealed, as well as details of each journey."
This has led me to see if my local bus services (Singapore) provide some sort of graphical timetables for the bus timings. This "quest" has then led to me a website that contains a gallery of Singapore bus brochures. For this blog post, I will focus on commenting on charts on 3 graphical timetables of the same bus route that has evolved over time. The bus service that I have chosen is the one that services my alma mater.
There are 2 main charts in this brochure. 1 with the pie charts representing the colour legend for the bus frequency and the bus frequency on the different days and times. At first glance, the colours used to represent the timings seem to be accessible with a quick check on Adobe Colour. The grids in the stacked bar chart representing the bus service time for the day break down the hour marks for readers.
The updated version uses a stem and leaf plot (discussed in a previous post) to show the timings of the bus arrival times at the first stop. I do not see stem and leaf plots being used frequently these days, but this helps to arrange the timings shown hourly. It also helps readers to determine which hours have a higher frequency of bus service which can also be seen from the colour-coded timeline.
The second edition updates not only come with a change in the main timetable and its colour legend, but it also includes icons that identify the nature of the stop locations on the route map. The thing that has been removed is the pie chart which represents a clock face. It has been replaced with simple colour coding for the legends. Perhaps, an improvement as the pie charts say the same thing as the words, but it takes more time to decipher than the words. The stacked bar chart for the timelines no longer has individual gridlines for each hour. This gives off a cleaner look in the spirit of data-ink maximisation. The stem and leaf plot has been replaced by a table that lists the timings at a glance. It is hard to say which is better. The stem and leaf plot allows users to find the hour mark easily, but this version had to break the single-day timeline into 2.
All in all, it has been interesting to see how the graphical timetable has changed over time for the bus route I used to ride. The data viz enthusiast in me would have preferred the updated version with the cleaner bar chart from the second edition and the stem and leaf plot from the first edition. Nonetheless, the general population who are the audience may just prefer an easier way to read time regardless of aesthetics, principles or charts used. Who knows? A market study might already have been done to determine the updates made.