I was asked if Sankey diagrams could meaningfully be used to visualize passenger loads on a tram or bus line. Here is what I came up with:

These are fictitious values. I just labeled the stops A, B, C, … and decided to go for a short feeder line. At the last stop all passengers get off (e.g. to transfer to a train).

At each stop there are passengers that get on (green) and get off (red). The number of pax on the bus is shown by the blue arrows.

The profile would probably look differently at different times of day, so depending on the data availability one would have to create diagrams for off-peak/peak hours, weekdays/holidays and so on.

Your thoughts?

4 Responses to “Visualizing Passenger Boarding/Alighting”

  1. phil Says:

    I like the concept, but I would recommend that the “Boarding” and “Alighting” arrows be distinguished by more than just color. I think if the Boarding arrows flowed down from the top, and the Alighting arrows flowed down toward the bottom of the page, that would help make the diagram easier to read.

  2. phineas Says:

    @phil: good point! Thanks for this suggestion. I’ll have the red ‘Alighting’ arrows exit below.

  3. Gerardus Says:

    Then the main trunk wanders upward though… hmmm… terrible being perfectionist 🙂

  4. phineas Says:

    @Gerardus: When doing a Sankey diagram I always find that the “fine tuning”, giving it the final touch, can be quite time-consuming. Depends on your degree of perfectionism when to stop 😉

    Here is a version with phil’s suggestion.
    Alternative version, out arrows downward
    Indeed the main trunk now kind of wanders upward, as you said.