## Learn how to model transport in a scalable way in Mobius!

In this article you will learn how to **model your transport in a scalable way in 5 steps**.

Before you start reading this article, make sure you have read the first three articles on transport or that you have watched the corresponding video tutorials. If you haven't done that yet, we recommend you to read the articles Step 1 - "Calculating ton kilometer", Step 2 - "Linking transport to objects" & Step 3 - "Adding references: tips & tricks".

The functional unit used to represent transport in the Ecoinvent database is tonne-kilometer (metric ton*km), which represents the transport of one tonne of goods over one kilometer. But this is actually a bit of an intransparent unit because the amount of weight and the number of kilometers that you're transporting are combined into one number. You cannot easily pull them apart again without knowing one or the other. Sometimes it would actually be very convenient if you could *scale the number of tonne-kilometers based on the amount of mass that you're transporting*. This can be done when the distance for multiple goods is identical (i.e. same supplier), but the weight of the goods that are transported is different.

**Step 1: Create a new transport object**Go to the object library and create a new object by clicking the plus sign (+) and give it a recognizable name. For example “150km transport from supplier ‘X’ to factory ‘Y’”. Fill in kg as a unit, so we can make it scalable by mass. This is because the distance will be the same for every material that is transported from supplier ‘X’ to factory ‘Y’ (see the picture below).

**Step 2: Calculate the tonne-kilometer (tkm) for 1kg of material for a given distance. **In this case, the distance from supplier ‘X’ to factory ‘Y’ is 150km. First, convert the weight from kg to ton (divide by 1.000). Thus, the weight of the material = 1 kg / 1000 = 0.001 ton. Multiply this by the distance. This gives: 0.001 * 150 = 0.15 tkm.

**Step 3: Add a new subitem underneath the object "150km from supplier ‘X’ to factory ‘Y’"**

Add the transportation mode in the model by clicking the plus sign (+) button to add a new subitem. Fill in the value you just calculated for 1kg of material transported over 150km = 0.15 tkm (see the picture below).

**Step 4: Add an impact reference (dataset)**Read the previous article Step 3 - "Adding references: tips & tricks" to find the correct reference from the database.

**Step 5: Add the object "150km from supplier ‘X’ to factory ‘Y’" to your product or material**

Go to your product or material you want to add the transport object to. In this example, we want to add transport to cotton yarn. Add the object of “150km transport from supplier ‘X’ to factory ‘Y’” to the cotton yarn in the model by clicking the plus sign (+) button. Add the amount of cotton yarn that is transported. In this example, 0.24 kg of cotton yarn was transported 150km from supplier ‘X’ to factory ‘Y’ (see the picture below).

**The result: **Mobius automatically scales the tonne-kilometer to the correct value. This means that you don't have to calculate the tonne-kilometers yourself. Time saver alert! ⏰

Curious how this works for other units as well? Our environmental specialist, Emma, will demonstrate how to model your transport in a scalable way in the video below.