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Guidance

Vehicle emissions carbon tool (VECAT)

Vehicle emissions carbon tool to quantify road user carbon emissions for scheme appraisal.

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Request an accessible format.
If you use assistive technology (such as a screen reader) and need a version of this document in a more accessible format, please email webmasterdft@dft.gov.uk. Please tell us what format you need. It will help us if you say what assistive technology you use.

Details

The vehicle emissions carbon tool (VECAT) allows transport practitioners to quantify road-user carbon emissions.

You can use it to:

  • annualise road-user emissions and calculate emissions over a set appraisal period
  • estimate the long-term carbon impact of a transport scheme as part of a business case

The tool works on a link-by-link basis using the parameters and formulas from DfT’s Transport analysis guidance (TAG) and the TAG data book.

Read the user guidance on this page and download the Excel spreadsheet to use the tool.

For any queries about VECAT, contact: vecat@dft.gov.uk.

Updates to this page

Published 16 October 2025
Last updated 19 December 2025 show all updates
  1. Vehicle emissions carbon tool (VECAT) updated.

  2. First published.

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