Help me do the math: "ton miles"

I watched a Modern Marvels program on television that showed how train locomotives are constructed. During the program, a claim was made that a locomotive can move 1 ton about 200 miles on 1 gallon of fuel ( a recent CSX TV ad claims about 400). In contrast, the program said a truck can move 1 ton about 59 miles on 1 gallon of fuel. I am trying to verify the truck calculations by using data from two recent trips (NY to GA and GA to Ontario), but I fear my algebra is a bit weak.

Trip 1: Distance = 1,158 miles, total weight = 23 tons, total fuel consumed = 146 gallons.

Trip 2: Distance = 1,246 miles, total weight = 32 tons, total fuel consumed = 199 gallons.

The total weight includes the empty weight of the truck and maximum fuel load. If the "tons moved" in the claim means only cargo, then subtract 17 tons from the total weight.

Now, the miles/gallon and gallons/ton are easy enough to figure, but I do not understand how to translate that information into 1 ton moved by 1 gallon of fuel X number of miles. Can anyone here figure this out for me?

Kevin

Ton miles: number of tons times the number of miles. Thus 10 tons going two thousand miles is 10 x 2000 or 20,000 ton miles. Then divide by fuel consumed. As for the tare weight of the truck, I'm not sure you wan't to elminate that from the equation because it is part of the cost of the movement.

In your example, an AVERAGE of 27.5 tons was moved a TOTAL of 2404 miles, using 345 gals. of fuel.
You don't need algebra to compute the ton-miles as 66110 (2404 X 27.5). Dividing by 345 (the no. of gals. of fuel) yields a result of 191.6, the number of miles a gal. of fuel would move one ton of freight.
This calculation includes the tare weight; a much lower figure results if you exclude it.


Ocala Mike

Thank you Henry and Mike. I forgot about "ton-miles", which is a multiplication and not a division like MPG.

So, according to these calculations, my truck was moving freight at nearly 200 miles per ton per gallon, or just about what the Modern Marvels show claimed is the figure for trains. Just for your information, my second trip included traversing several ranges in the Appalacian (sp) Mountains.

The claim that trucks only get 59 miles per gallon per ton seems misleading. Using an example of a fully loaded truck (40 tons) going 2000 miles, the truck would have to burn 1356 gallons of fuel to get 59 miles per ton per gallon, or about 1.5 MPG (way way too low for even the heaviest leadfoot).

So, I'm not quite sure what to make of the claims by MM or CSX. Is there anyone that has the same kind of trip data for trains that I provided for my truck?

Here is some data we can use from another topic:

conrail_engineer wrote:A typical CSX freight is between 8000 and 10,000 tons. Typical fuel taken on would be between 2000 and 3500 gallons per unit...most trains with to locomotives. And Selkirk's roughly 400 miles away from Cleveland.

If we use the figures of 9,000 tons, 400 miles, and 3000 gallons, then the "typical CSX freight" gets 1,200 miles per ton per gallon. This would make it six times better than a truck.

It's 3,000 gals. PER UNIT, but there are two units, so you need to figure 6,000 gals. Your calculation would then be more like 600 miles per ton/gal.

Oops, my bad. Ok, so that train example still makes it three times more than a truck.

Hi,

I've been reading this site for a while but I have never left a comment before. I've actually had to do these sorts of calculations before and the data from your two truck trips is valuable but it leaves out some of the inherent overhead energy costs of trucking. That would be overnight idling, deadheading / return trip, or even fuel lost due to congestion.

The railroad fuel intensity given on the History Channel and by CSX is almost certainly drawn from the Transportation Energy Databook (put out by DOE) which takes data from the AAR. They use the total fuel consumption of the entire industry (or at least class I's which account for over 80%) and the total ton-miles. Your point to point truck delivery data did not capture all of the energy used to pick up and deliver the cargo to its end-user.

condu200 wrote:Hi,

I've been reading this site for a while but I have never left a comment before. I've actually had to do these sorts of calculations before and the data from your two truck trips is valuable but it leaves out some of the inherent overhead energy costs of trucking. That would be overnight idling, deadheading / return trip, or even fuel lost due to congestion.

The railroad fuel intensity given on the History Channel and by CSX is almost certainly drawn from the Transportation Energy Databook (put out by DOE) which takes data from the AAR. They use the total fuel consumption of the entire industry (or at least class I's which account for over 80%) and the total ton-miles. Your point to point truck delivery data did not capture all of the energy used to pick up and deliver the cargo to its end-user.

The inherent "overhead energy costs" are also part of railroading --- idling; deadheading (for which trucking has the advantage of more-easily getting backhauls); and congestion. One other very important factor that would mitigate trucking fuel inefficiency (vs. rail) is route circuity -- railroad circuity on a point-to-point basis runs around 8% (additional miles) more than highway miles, and often is much higher as railroads route via longer-distance routings to achieve volume via larger classification yards. While industry ton-miles are aggregated across all commodities, for lighter-weight density commodities like consumer products, which cube out before weighing out, the rail advantage would greatly shrink and I would wonder what, if any, fuel efficiency advantage would exist for rail.

QB 52.32 wrote: The inherent "overhead energy costs" are also part of railroading --- idling; deadheading (for which trucking has the advantage of more-easily getting backhauls); and congestion. One other very important factor that would mitigate trucking fuel inefficiency (vs. rail) is route circuity -- railroad circuity on a point-to-point basis runs around 8% (additional miles) more than highway miles, and often is much higher as railroads route via longer-distance routings to achieve volume via larger classification yards. While industry ton-miles are aggregated across all commodities, for lighter-weight density commodities like consumer products, which cube out before weighing out, the rail advantage would greatly shrink and I would wonder what, if any, fuel efficiency advantage would exist for rail.

QB 52.32,

You are completely correct that using railroads has an inherent energy overhead. I did not mean to infer that their was not one. My point was that this overhead is incorporated into the data used in the Transportation Energy Databook for rail while it is not incorporated in the data from two one-way truck deliveries.

In addition to that I would agree that using rail is probably more circuitous than road. (I have no idea where you got 8% from but it doesn't seem unreasonable to me.) Light-weight consumer goods already move almost exclusively by truck and have since the 70's. Railroad intermodal shipments are incredibly fast-growing but they still make up an incredibly small portion of the total cargo shipped by rail. I would bet we here so much about it is logistically difficult to coordinate with the slower moving bulk commodities and is very profitable to the railraods.

Another issue that I think you have missed is congestion delaying shipments by truck. If you have read the report by the National Surface Transportation Policy and Revenue Study Commission (http://www.transportationfortomorrow.org/final_report/), which I have you would realize that the congestion we are experiencing today is nothing compared to what is happening. Highway congestion is not in a linear relationship with traffic demand. At a certain point you hit a tipping point and congestion increases almost exponentially. On many major urban roads in the US we started hitting this in the early 90's or late 80's. Road construction cost is very closely tied to the price of oil (basic inputs of the road plus the necessary heat input on the work site). Rail is also somewhat energy intensive but this can be more easily centralized to a steel foundry or factory with the energy inputs coming from non-oil sources.

I think all of the combined plus many other issues come to a net energy and economic profit that can be gained by transferring freight to rail. This doesn't even begin to cover the environmental aspects.

QB, thank you for the interesting points.