Friday, December 3, 2010

A VMT oddity and the latest TWIP

I have been writing about the use of the monthly reports from the Federal Highway Administration (FHA) on vehicle miles travels, at intermittent intervals over the past couple of years. It provides an informal way of trying to see how fuel demand is going in the United States, and perhaps some indications of the recovery of the economy. The figures are now out for September 2010 and I was looking at the plot I usually use of the rolling 12-month average of miles driven:

Rolling 12-month VMT (Source FHA )

I hadn’t been paying much attention to the lower scale, it shows years and it wasn’t until I tried to see when it was that the driving was last at this level that I realized that the scale does not include years that end in 4 or 9. Which is my oddity for the day.

Other than that the recovery of driving seems to be holding up both in urban and rural areas, and generally across the country. Texas seems to be doing a little better than most, but other than that the picture appears to be, as the plot shows, one of steady growth at a rate similar to that before the great oil price boost.

Moving over to This Week in Petroleum the picture similarly shows nothing particularly out of the ordinary. The EIA is going to take a slightly different look at storage capacity data, and that is their front page story of the week, but as one looks at the plots, other than the slow creep up in oil prices, there is little untoward in them. Domestic production has continued to increase, lowering the need for imports, at a time of year when refinery inputs in general are down.

Source EIA

At the same time ethanol production is continuing its steady climb in production:

Source EIA

At a time when the gilt seems to be wearing off the ethanol gingerbread, the public discussion seems to be having little effect on that reality.

But other than that, nothing much of significance that I can see, (which doesn’t mean that I’m not missing something – perhaps that gasoline demand has dropped to the same level as last year?)


  1. You have to go back to 2002 in the EIA's statistics to find a lower four-week average for November. Yet the FHA graph seems to tell a different story. Why would that be?

  2. Sorry, that should be "four-week average gasoline demand"

  3. OK, it was a silly question. I have to compare 12 months to a 12-month average. Doing that, there's no big disconnect between the two data sets.

  4. Since even under the Obama Administration, the Federal gov't does not make US citizens fill out forms in triplicate each month listing miles travelled in each vehicle, the "Vehicle-Miles Traveled" has to be an estimate based on actual measurements of something else -- or maybe even based on estimates of measurements of something else.

    For example, Gov't could get estimates of fuel sold each month -- but if people think prices are going up and all fill up their vehicle tanks, there would be a temporary change in the relationship between fuel sold & miles travelled. Etc, etc.

    It would be better to focus on actual measurements.