TAG unit A4-2 distributional impact appraisal

Guidance on the analysis of distributional impacts caused by transport interventions.


TAG unit A4-2 distributional impact appraisal

This file may not be suitable for users of assistive technology. 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 Please tell us what format you need. It will help us if you say what assistive technology you use.


Documentation giving guidance on the analysis of various distributional impacts caused by transport.

The transport impacts considered are:

  • user benefits
  • noise
  • air quality
  • accidents
  • severance
  • security
  • accessibility
  • personal affordability

and these are analysed for their effect on individual social groups.

This Transport Analysis Guidance (TAG) unit was updated in December 2015 to reflect changes to TAG unit A3 (environmental impact appraisal) relating to the valuation of noise impacts. The changes were:

  • the addition of older people as a social group; and
  • the removal of the suggestion that analysis be completed a single year or 15 year after scheme completion

These amendments are made due to the Environmental noise: Valuing impacts on: sleep disturbance, annoyance, hypertension, productivity and quiet (PDF, 775KB) report, released by Defra November 2014.

The previous version of this unit was TAG unit A4-2 distributional impact appraisal.

TAG provides information on the role of transport modelling and appraisal, and how the transport appraisal process supports the development of investment decisions and business cases.

Published 23 December 2015