Thoughts on the original chart
The chart being made over is actually a series of Tableau dashboards within a story (set of tabs). I like the way I can work through the story from an overview of the data to some summary charts and then down to some detail. The card type dashboard interested me. They key story that jumped out to me was that around 70% of trips were made using an Adult Opal Card. I don’t think we need to see this proportion visually per month and then again per line. Perhaps other angles from the data could have been visually represented too? Nice dashboard though and I enjoyed clicking through to the map for some context.
I wanted to try getting the breakdown by ferry line, card type and month onto one viz so targeted an iPad portrait layout. First up I tried a heat map. This was okay but not quite what I was looking for.
A line or bar chart of trips per month, with a panel per ferry line and card type worked well but there were too many card types to show nicely! Also the trips using certain card types (e.g. employee) were negligible compared to the main types. Grouping the types together allowed me to fit everything in. School and Concession (concession being for tertiary students) seemed to bundle in with Child / Youth quite nicely, and single trips could be bundled in with other outliers.
The viz ended up looking like this:
This allows me to see at a glance the top lines and card types, plus I get a brief idea of trends over time from the monthly bars (with labels on the first and max values). In some ways it’s working a little bit like a heat map if you consider whitespace a lack of heat in comparison to the space take up by the bars. In some ways the bottom right part is a little empty. Still that does tell a story.
The viz is also available on Tableau Public.
A note on image reuse
My original design concept had a different image at the top of each column; I wanted to use images of the main Opal card types. My thoughts were that this would add useful context for those users who were familiar with Sydney ferries or similar networks. It would be clear at a glance that column one related to the ferry lines and the subsequent columns to the various card types.
Unfortunately whilst the data is open access under a creative commons licence, their logos and trademarks are not. I interpreted this to mean that I couldn’t use the Opal card type images, because they included trademarked logos. I followed up with the relevant department (who were very helpful) just to be sure and had those thoughts confirmed. No drama – it was useful experience to research this angle and I’ve still been able to use coloured rectangles to give my viz some context. In fact if I were redoing the viz I’d probably use that space for some summary numbers whilst retaining the colour for context. I’d also revisit my column headings to make the groupings clearer.