In this article, I’m writing about the 4th dashboard I build this week. The topic is the crash stats in Victoria, and I’m focusing on the collisions in the Melbourne CBD area.


The dataset is from Vic Roads; it contains all accident details from 2006 to 2020. Data is pretty clean, but it’s not in the same data source; you can either join the tables in Alteryx or build a relationship in Tableau, as in the past 3 days, I did all data manipulation in Alteryx, so I decide to build a relationship in tableau directly.

Dashboard Designing

After data exploration, I find the topic I’m interested in; As I said before, there is not much on data preparation, I spend the most time on designing, inspired by new zen master Judit Bekker, her dashboards are really awesome at designing, which create a rounded map in Tableau, basically create an image with a transparent circle (shows as below) in Adobe Illustrator or Figma, you can also make it in PowerPoint, and then float this image above the map, take this image to the dashboard, after that you need to duplicate the map sheet and drag the duplicate map on top of the image, the last thing about this duplicate map is change map background to none, in my case, because the bottom layer map is tiled in the dashboard; therefore I have to find a transparent map background to make it working properly, Mapbox is one of the solutions. Please check the below gif image; it demonstrates how to achieve this. The most difficult part finish, other charts just floating on top of the map.

Custom Map

The map I used in this dashboard is not a default map in Tableau; it’s called Mapbox; there are many great custom maps you can choose and custom based on that. The Mapbox studio gallery link is here.


I think it’s ok for one day project, but it could be better if I have more time. I hope you like this viz. You can also find mine viz in here.

Jason Hu
Author: Jason Hu