Rolling with the homies to work. How my vehicle miles traveled (VMT) have changed.
Here you can see how my commuting patterns have changed over the past few years. I have owned a 1998 Volvo S70, a Ford Focus, and a Chevy Equinox. The Volvo was driven exclusively by me, and the Focus/Equinox have been a mix of me and my wife. For the past several years I have been recording my mileage in a program called Vehical. It is available for the iPhone. Unfortunately it only records 1 car, but since my cars were all a very different miles, its was easy to distinguish over the years. This brings me to the point of this visualization, which is adjusting Tableau Table calcs to display disparate quantities in a comprehensible way.
By using table calcs, we can force all lines into the same range so that they can be compared easily. Now we can see some interesting things. First off, although my wife and I have traded off driving the Equinox and Focus, for the entirety of my vanpooling I was driving the Focus (orange). You can see a significant departure in cumulative mileage of the focus from the other two cars. In addition, although the Equinox is no longer used to commuting, we put more road-trip miles on it and those are far more visible than the above graph.
In addition there are other questions that remain unanswered. For instance, how am I doing compared to the US average. Although diagonal reference lines are very-much possible, I will choose another approach and create a rate table calculation. I used nearly the same formula from above, but used “-1″ to tell Tableau to make the calculation relative to the previous value instead of “first().” More tends become visible and road trips become far more obvious.
Sweet! Now as you can see some of the trends are way more obvious. Road trips are obvious and a job change during the Volvo days starts to become more visible. In additiona, I added a reference line at the 40 Mi/Day mark. This represents the current VMT that I found from the Federal Reserve. If you’re interested in US economic data, then the FRED is it. They also have a nice Excel add-in, and their data is also in .txt files directly linkable via the web.
US 12 month rolling VMT Per working-age population:
Now we will add a moving average table calc. This mellows out the data and you can see how the trends have moved over time. Tada! I’m driving much less than average.