cartky.org

Gas tax, in cents per gallon, is starting to come under fire. How are we to maintain our roads if everyone switches to plug-in electric cars? Although this may seem like an absurdly far-off event to worry about, Oregon is already exerimenting with taxing motorists per-mile. That's silly too, since it ads no incentive to conserve gasoline.

I asked "What would a completely fair tax of motor vehicles look like?" Taxing people for the road damage they cause, the carbon & other pollutants they emit, and the threat they pose to others should all be considered. This is the answer I received:

Roadway damage:

It goes up by weight divided by the number of axles to the 4th power, so a 2 ton car does 16 times more damage than a 1 ton car. If we assume the 2 ton, 2 axle car is currently paying it's share of the roadway damage at 1.5 cent/mile, then a 20 ton semi truck on 5 axles should pay about $4/mile. Right now, the trucks aren't paying anywhere close to that, (they have good lobbyists,) and if they did pay their share then it would be obvious that the cars are actually paying too much at 1.5 cents, so the real numbers might be more like 1 cent/mile for cars, and $3/mile for 20 ton trucks, but that is roughly what that part of the equation looks like. (A bicycle does less than a 1 cent/year even if the rider never sleeps or eats or otherwise stops.) Yes, that hurts trucker, but it doesn't really hurt freight movement: There are much cheaper ways to ship heavy things long distance than the interstate highway system right now, so that only really works out to $3/mile for the last few miles of the trip, with the rest being done by train/boat/whatever. However, there is also the capacity issue: A single semi truck takes up about the same amount of room on the road as two cars, so the truck should simply pay double, (and not 300 times,) the cost of any roadway expansion project, and since some of the gas tax "maintenance" money is being spent on roadway expansion, we'd need to break those apart, and that might put the cars charges at 2 cents a mile instead of 1, although the trucks would still be very close to $3/mile. Ultimately, capacity should be handled as a congestion charge, and many of those are in the $5-$10/day category in the central city.

There is also parking, and people have written whole books about that, but the estimate says that we should charge somewhere around $100k/car for all the parking spaces that go with them. (That isn't a typo, read "The high cost of free parking." (In Japan you actually have to own a parking space in order to license a car, in much the same way that we require proof of insurance.)

Carbon:

The gas tax is not a carbon tax, and if we wanted to add that to the gas tax, that is in addition to the roadway damage/capacity issues. In 1991, Sweden passed a carbon tax at $100/ton, and there are 19 pounds of CO2 in a gallon of gasoline, so that is $.95/gallon, or 4 cents a mile at 25 mpg. For a 12,000 mile/year driver, that works out to $450/year, and while that may seem high, it quite a bit cheaper than dealing with the damage from global warming. As such, Sweden has since decided that the carbon tax is too low, and have raised it to $150 in 1997, and have discussed raising it again recently.

Danger to others:

In theory, insurance rates should reflect how much danger you are to other roadway users, although most people only have a hundred thousand in insurance, not the $2-3M that taking people's lives actually costs. But liability coverage alone ran me $500/year, back when I drove 12,000 miles/year and I have a perfect driving record, so that is 4 cents a mile for a safe driver in a fairly safe car, and it would probably go up from there. Of course, not all miles are equal: Freeways kill far less people per mile than downtown or 82nd, so...