TAG unit M4 forecasting and uncertainty
Transport analysis guidance (TAG) provides information on the role of transport modelling and appraisal.
Documents
Details
This document gives guidance on the analysis of forecasting and uncertainty in transport appraisals.
The guidance is supplemented by the Uncertainty Toolkit.
The previous version of this guidance was released in May 2023.
TAG provides information on the role of transport modelling and appraisal, and how the transport appraisal process supports the development of investment decisions to support a business case.
Updates to this page
Published 31 May 2019
Last updated 3016 NovemberOctober 2023
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Update history
2025-12-11 10:00
‘TAG unit M4’ and ‘TAG uncertainty scenarios: upcoming changes’ updated.
2025-10-16 09:30
Added forthcoming change: updates to TAG uncertainty guidance.
2023-11-30 10:00
TAG unit M4 updated.
2023-10-19 10:00
Added forthcoming change about appraisal guidance updates.
2023-05-31 10:00
TAG unit M4 updated.
2023-04-19 09:43
Added forthcoming change: spring 2023 data book and guidance updates.
2023-04-05 14:14
Added forthcoming change: accounting for COVID-19 in transport modelling.
2022-12-21 15:35
TAG unit M4 forecasting and uncertainty updated.
2022-08-08 09:37
Forthcoming change to guidance note added, giving details of updates to be made in November 2022.
Details
This document gives guidance on the analysis of forecasting and uncertainty in transport appraisals.
The guidance is supplemented by the Uncertainty Toolkit.
The previous version of this guidance was released in May 2023.
TAG provides information on the role of transport modelling and appraisal, and how the transport appraisal process supports the development of investment decisions to support a business case.
Updates to this page
Published 31 May 2019
Last updated 3016 NovemberOctober 2023
+ show2025
href="#full-history">+ show all updates
-
Update history
2025-12-11 10:00
‘TAG unit M4’ and ‘TAG uncertainty scenarios: upcoming changes’ updated.
2025-10-16 09:30
Added forthcoming change: updates to TAG uncertainty guidance.
2023-11-30 10:00
TAG unit M4 updated.
2023-10-19 10:00
Added forthcoming change about appraisal guidance updates.
2023-05-31 10:00
TAG unit M4 updated.
2023-04-19 09:43
Added forthcoming change: spring 2023 data book and guidance updates.
2023-04-05 14:14
Added forthcoming change: accounting for COVID-19 in transport modelling.
2022-12-21 15:35
TAG unit M4 forecasting and uncertainty updated.
2022-08-08 09:37
Forthcoming change to guidance note added, giving details of updates to be made in November 2022.
Details
This document gives guidance on the analysis of forecasting and uncertainty in transport appraisals.
The guidance is supplemented by the Uncertainty Toolkit.
The previous version of this guidance was released in May 2023.
TAG provides information on the role of transport modelling and appraisal, and how the transport appraisal process supports the development of investment decisions to support a business case.
Updates to this page
Update history
2025-12-11 10:00
‘TAG unit M4’ and ‘TAG uncertainty scenarios: upcoming changes’ updated.
2025-10-16 09:30
Added forthcoming change: updates to TAG uncertainty guidance.
2023-11-30 10:00
TAG unit M4 updated.
2023-10-19 10:00
Added forthcoming change about appraisal guidance updates.
2023-05-31 10:00
TAG unit M4 updated.
2023-04-19 09:43
Added forthcoming change: spring 2023 data book and guidance updates.
2023-04-05 14:14
Added forthcoming change: accounting for COVID-19 in transport modelling.
2022-12-21 15:35
TAG unit M4 forecasting and uncertainty updated.
2022-08-08 09:37
Forthcoming change to guidance note added, giving details of updates to be made in November 2022.