# A4 Transportation Emissions

A4 emissions, or transportation emissions, are associated with deliveries of materials from the point of manufacture to the jobsite. This includes activities such as ready-mix trucks delivering concrete to the jobsite, deliveries of steel and other materials. EC3 has an A4 calculator to help users easily convert fuel from these activities into emissions or global warming potential (GWP).

To access the A4 calculator, click on the "A4 Transport" tab in the building project planner. The materials, quantities, units, collections and EPDs that are populated in the "A1-A3 Manufacturing" tab will automatically carry over to the A4 calculator. 

EC3 calculates the impact of transport from manufacturing plant to project site for each material. This result is then shown as A4 transportation impact. This calculation takes into account:

1. product weight
2. transportation mode(s)
3. transportation distance(s)

Product weight is the mass per declared unit when available; otherwise EC3 calculates it from the default density for the product category.  You can manually enter a more accurate product weight, for example to include packaging (if known).

Transportation mode defines the carbon footprint per ton of product transported over a km or mi distance, i.e., [kgCO2e ](https://www.wikidata.org/wiki/Q57084901)per [t](https://www.wikidata.org/wiki/Q191118)\*[km](https://www.wikidata.org/wiki/Q828224) or [ton](https://www.wikidata.org/wiki/Q469356)\*[mi](https://www.wikidata.org/wiki/Q253276). Our [list of transportation modes](https://docs.google.com/spreadsheets/d/1sviO5qm9bPKSm1biDl9i64yU1_hX17-1Pnduebnj9cc/edit#gid=339076095) and the associated impact factors come from regional LCA datasets, such as [USLCI](https://www.lcacommons.gov/) in the United States [\[1\]](https://www.zotero.org/google-docs/?66e278). Associated impacts are well-to-wheel, i.e., they include both fuel production and combustion emissions, unless noted otherwise in the transportation mode table.

Transportation distance can be custom calculated, but EC3 provides a default initial estimate.

If the user has selected a facility-specific product EPD, EC3 uses the straight-line distance from the manufacturing facility to the project site, plus a [40% routing factor](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3835347/) to account for the actual road, rail, and waterway routes [\[2\]](https://www.zotero.org/google-docs/?jevV21).

If no product EPD is selected yet, EC3 uses a [default distance](https://docs.google.com/spreadsheets/d/12ha9Nb5jClIqez-SmYJK9OfMMix01PmZbwO1amdNu28/edit#gid=1802945804) and mode for the general product category that was selected. These default values represent the typical distance based on national or regional data (e.g., U.S. [Census Bureau’s Commodity Flow Survey](https://www.census.gov/programs-surveys/cfs.html) in the United States [\[3\]](https://www.zotero.org/google-docs/?AhhHnz)).

You can also enter specific info about multiple transportation modes and distances manually, where you have more complete information.  We recommend [Ecotransit ](https://www.ecotransit.org/en/)as a resource.

To calculate the A4 transportation impact, we multiply: 

GWP\_a4\_leg1 = product\_weight \* transport\_mode\_gwp\_intensity \* leg\_distance 

For multiple legs, each leg is calculated as above and results of all legs are summed:

GWP\_a4\_total = GWP\_a4\_leg1 + GWP \_a4\_leg2 + GWP\_a4\_leg3 +  …    

As usual, EC3 handles the unit conversions.

## References

[\[1\] National Renewable Energy Laboratory, USLCI Database, National Renewable Energy Laboratory Golden, CO, 2021.](https://www.zotero.org/google-docs/?H5xFAJ)

[\[2\] F.P. Boscoe, K.A. Henry, M.S. Zdeb, A nationwide comparison of driving distance versus straight-line distance to hospitals, Prof. Geogr. 64 (2012) 188–196.](https://www.zotero.org/google-docs/?H5xFAJ)

[\[3\] U.S. Department of Transportation, U.S. Department of Commerce, U.S. Census Bureau, 2017 Commodity Flow Survey, Washington, DC, 2020. www.census.gov /content/dam/Census/library /publications/2017/econ /ec17tcf-us.pdf.](https://www.zotero.org/google-docs/?H5xFAJ)

<br>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.buildingtransparency.org/ec3/main-features/plan-and-compare-buildings/a4-transportation-emissions.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.