# Question About Transportation Modeling

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Hi!

I want to model the transportation of components from suppliers to the main manufacturing facility. Every shipment is made by truck. I plan on using predefined processes available in the database I use. However, I am a bit perplexed concerning the unit kgkm (or tkm).

Let's say there are two scenarios. 1) A truck of a certain type transports a 10 kg package a distance of 100 km. 2) The same truck transports a 10 000 kg package a distance of 100 meters. For both scenarios, as I've understood it, one would enter the value 10 000 kgkm (10*100 = 10 000*0.1 = 1000 kgkm). But it would logically seem reasonable that scenario 1 would produce more emissions than scenario 2, or is that an unreasonable assumption?

Is there something that I've misunderstood about how these processes are meant to be used and interpreted?
in openLCA

## 2 Answers

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by (74.1k points)
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Hi Nils,

good question and you are right, the tkm calculation is often not too exact, but it is as you describe: transporting 2t 1km is the same as transporting 1t 2km (with the same e.g. truck).

Best wishes,

Andreas
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by (230 points)
There are often underlying assumptions on truck capacity and load factors. For example, it is assumed that a truck with a 10 000 kg capacity would not transport just one 10 kg package but many of them, allocating only part of the overall truck emissions for the trip to the one 10 kg package.
by (100 points)
Hi, I wanted to measure the transportation between China ,Shanghai port and GĂ¶teborg port Sweden which is almost 21000 km. My functional unit is a. Carton of tissue , 6.58 kg , 48 roll inside . I assumed that it is shipped by a 22000 TEU ship , in every TEU can be placed 560 carton . So now how can I measure the amount of transportation in t.km?