This rarely happens. So rarely that I don’t remember the last time, if ever, I had a clean drive to my destination. You know, the drive where you not only hit every single green light, but cars shift out of your lane so you don’t have to compensate for their slowness. Ah! It was most satisfying.
Putting that obviously aberrant experience aside, most times I drive I seem to hit every traffic light and inevitably get stuck behind morons that can’t drive. This is woefully true when I am running late for an appointment. “C’mon dude! Can’t be lettin’ everyone in!” I feel as if the Fates were mocking me and laughing harder with each curse word I would let loose. (You’ll have to trust me that I am a defensive driver. I promise.)
But, is it really so? Are there alway special causes? Would it all be okay if ‘this guy’ or ‘that girl’ would just drive better — like me? I decided to check. Everyday I’ve been logging my commute time to and from work. They are shown in the charts below.
Sure, the average (solid red line) commute to work (~35 minutes) is less than the average commute from work (~43 minutes). And, yes, the variation about the average commute to work is a lot less than that about the average commute from work. But, all points are within my control limits (dashed red lines)! That means, all the variation about the average is from common causes! There are no special causes.
If there were special causes, as would have been highlighted by points outside the limits, I could do something about them. If I ran out of gas during my trip which then added to my commute, I could start my future trips with a full tank of gas. If my tires ran flat because they were bald and delayed me, then before all future trips I would make sure my tires were okay. If there was an accident, then I have a legitimate excuse for being late.
Thing is I have no control over common causes for variation like traffic signals changing to red or getting stuck behind some random slow driver or rain or fog. Sometimes, all these things and others combine in a ‘perfect storm’ to make the commute unusually long… or unusually fast. What the charts tell me is, by and large, the time it takes me to get to work will be between 26 – 45 minutes, and the time it takes me to get home from work will be between 27 – 59 minutes. No amount of frustration is going to change that.