Guidance

TAG data book

Historical and reference information on all the appraisal and modelling values referred to in the transport analysis guidance (TAG).

From:: Department for Transport
Published: 29 November 2018
Last updated: 2916 ~~May~~October 2025 — See all updates

Documents

TAG data book

5.62 MB

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Forthcoming change: appraisal data update

https://www.gov.uk/government/publications/tag-forthcoming-changes/forthcoming-change-appraisal-data-update

Details

The TAG data book provides all of the appraisal and modelling values referred to in TAG guidance. The data book features historical information and factual reference information about the appraisal and modelling values.

The previous version, TAG data book v1.24, was released in November 2024.

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.

Published 29 November 2018

Last updated 2916 ~~May~~October 2025 + show all updates

16 October 2025
Added forthcoming change: appraisal data update.

29 May 2025
TAG data book updated.
17 April 2025
Added 'Forthcoming change: appraisal data update'.
28 November 2024
TAG data book updated and forthcoming changes for May 2025 added.
17 October 2024
Added 'Forthcoming change: updates to economic and demographic data and clarified guidance on rail appraisal'.
30 May 2024
Unit updated and May 2024 forthcoming change note removed.
25 April 2024
Forthcoming changes added.
30 November 2023
TAG data book updated.
19 October 2023
Added forthcoming change about appraisal guidance updates.
6 October 2023
Added forthcoming change about carbon valuation.
31 May 2023
TAG data book updated.
19 April 2023
Added forthcoming change: spring 2023 data book and guidance updates.
18 January 2023
TAG data book updated.
30 November 2022
TAG data book updated.
19 October 2022
Forthcoming changes for November 2022.
16 June 2022
Tables A1.3.11 and A1.3.12 in 'TAG data book: fleet assumptions' have been corrected to reflect the addition of electric PSV energy consumption parameters.
30 May 2022
Updated TAG data book. Added data book: fleet assumptions, and a forthcoming change note on fleet assumptions.
29 April 2022
Forthcoming change to guidance note added, the note details guidance alterations to be implemented in May 2022.
29 November 2021
Updated TAG data book.
13 October 2021
Notification of forthcoming change for November 2021.
11 October 2021
Added forthcoming change data book with updated carbon values and marginal external costs.
30 July 2021
Added latest version of TAG data book and removed sensitivity testing document.
19 May 2021
Added forthcoming change to TAG data book.
23 July 2020
Added new data book: TAG data book - sensitivity training.
9 July 2020
Annual Parameters source note corrected to refer to source material referenced in November 2019 forthcoming change, and outturn data based on ONS March 2020 publications. Marginal External Costs corrected for weighted average of congestion bands (A5.4.1), band 5 London motorways (A5.4.2), and Scotland values (A5.4.4). Environmental analysis tables corrected for fuel/electricity price forecasts and fleet splits by fuel type. Average value of accident prevention per casualty (A4.1.1).
29 May 2020
Update to outturn and forecast data for GDP, inflation and average earnings, based on estimates from the ONS and projections from the OBR (due to be published alongside Autumn budget); update to the forecast values for Marginal External Costs based on estimation by the Department’s National Transport Model. Tables A5.4.1 - A5.4.4 will be updated as a result; update to the professional drivers’ values of time to reflect latest Annual Survey of Household Earnings data.
22 October 2019
October 2019 forthcoming changes document added.
11 July 2019
Corrected light goods vehicles formulas in table A1.3.10a.
4 June 2019
TAG Data Book re-published with slight correction affecting the look-up year in sheet A1.3.7.
31 May 2019
Updated reflecting the forthcoming changes given new forecasts from the ONS and OBR.
1 May 2019
2019 forthcoming changes document added.
29 November 2018
First published.

TAG data book

Documents

TAG data book

Forthcoming change: appraisal data update

Details

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