Guidance

Forthcoming change: spring 2024 data book and guidance updates

Updated 25 April 2024

Description: Updates to economic and demographic data, greenhouse gases valuation, fuel and energy prices, electricity emissions factors, plus updated guidance on station improvement appraisal and agglomeration elasticities.

Units: TAG data book; A2.4 (productivity impacts); A3 (environmental impact appraisal); A5.3 (rail appraisal); active mode appraisal toolkit (AMAT) and appraisal workbooks

Change announced: April 2024

Expected release date: May 2024

Description

This forthcoming change sets out updates to several TAG units and the TAG data book, to reflect the latest evidence and guidance for appraisal and modelling. Additionally, the active mode appraisal toolkit (AMAT) and relevant appraisal workbooks will be aligned with the latest evidence and guidance in TAG.

All data book and guidance updates will become definitive in May 2024, after which an updated version of TUBA, COBALT and WITA will be made available to reflect the updated appraisal values.

Detail of changes

Economic and demographic data

The TAG data book displays a range of economic and demographic data sets used in the appraisal of transport interventions. To maintain the accuracy of appraisals, these data sets are updated in line with new releases of data from the Office for National Statistics (ONS) and Office for Budgetary Responsibility (OBR). A new version of the TAG data book (v1.23), to be released definitively in May 2024, will incorporate outturn estimates from the ONS, as well as minor changes to medium-term forecasts from the OBR‘s economic and fiscal outlook. These changes will be implemented in the annual parameters table of the data book as follows:

• GDP deflator: updated for 1990 to 2023 using the ONS MNF2 series, published 15/02/2024; and for 2024 to 2028 using the forecasts from the OBR EFO March 2024, published 06/03/2024
• real GDP: updated for 1990 to 2023 using the ONS ABMI series, published 15/02/2024; and for 2024 to 2028 using the forecasts from the OBR EFO March 2024, published 06/03/2024
• population: updated for 2022 using the ONS UKPOP series, published 26/03/2024; and for 2023 to 2028 based on population implied by GDP and GDP per capita growth from OBR EFO March 2024, published 06/03/2024
• households: updated for 2023 using the  ONS families and households data set (if published prior to data book release); and for 2024 to 2028 calculated from the population growth as implied by the OBR EFO March 2024, published 06/03/2024

In table A1.2.1 of the data book as follows:

• construction output prices index (COPI): updated for 2023 to 2024 using the ONS COPI series (if published prior to data book release)

And in table A5.3.1 of the data book as follows:

• GDP deflator: updated for 2010/11 to 2023/24 using the ONS L8GG series, (if published prior to data book release); and for 2024/25 to 2028/29 using forecasts from the OBR EFO March 2024, published 06/03/2024
• CPI, RPI: updated for 2010/11 to 2023/24 using the  ONS D7BT and CHAW series respectively, published 17/04/2024; and for 2024/25 to 2028/29 using forecasts from the OBR EFO March 2024, published 06/03/2024
• average earnings: updated for 2010/11 to 2028/29 using data from the OBR EFO March 2024, published 06/03/2024

Additionally, a functionality has been added to the annual parameters table to enable users to change the base year of historic GDP-related values (real GDP, GDP per person or GDP per household), when using outturn values in analysis. This function uses the ratio of nominal GDP (using the ONS YBHA series, updated 15/02/24) to real GDP to scale the historic real GDP value. By default, the base year parameter is set to the latest ONS base year (currently 2019). Note changing the GDP base year does not change annual growth rates, indices or forecast figures.

Those appraisal workbooks that utilise the annual parameters table for price adjustments, discounting and uprating will also be updated accordingly. The relevant workbooks are:

• greenhouse gases
• air quality
• landscape monetisation
• noise
• noise (aviation)
• active mode appraisal toolkit
• cost proforma

Traded carbon valuation

TAG unit A3 advises that scheme impacts on greenhouse gas (GHG) emissions should be valued for appraisal purposes using cross-government carbon values published in TAG data book table A3.4, and that where such emissions are under the scope of the UK Emissions Trading Scheme (UK ETS), the applicable appraisal values should be adjusted to exclude any proportion already accounted for within UK ETS allowance prices.

In November 2023, the Department for Energy Security and Net Zero (DESNZ) published new traded carbon values for modelling purposes. TAG unit A3 will recommend that adjustments required for the valuation of traded emissions are informed by these values – specifically the DESNZ market carbon values series for adjustments required for central/core analysis, and the DESNZ high and low sensitivity series for adjustments required for sensitivity tests. Adjustments for sensitivity tests may be informed by other values if appropriately justified. The new traded carbon values will be published in the TAG data book and added to TUBA.

Adjustments required for traded emissions outside the UK ETS should be informed by carbon price data from reliable sources and supported by reasonable assumptions. Where schemes are expected to impact traded emissions under multiple carbon pricing regimes, analysts should refer to mode-specific appraisal guidance. Guidance for aviation scheme appraisal is provided in TAG unit A5.2.

Fuel and electricity prices

TAG unit A1.3 advises that fuel costs for use in appraisal should be informed by fuel (petrol, diesel and gas oil) and electricity prices published in supplementary Green Book guidance. In November 2023, the Department for Energy Security and Net Zero (DESNZ) published an update to these values, and these will be incorporated into table A1.3.7 of a new version of the TAG data book (v1.23), to be released definitively in May 2024.

The updated fuel and electricity price figures show a significant decrease in the long-run resource cost of liquid fuel types (petrol, diesel and gas oil) with prices settling 32 to 37% lower from 2035 to 2100, compared with the current data book. This decrease has been driven by revised long-run forecasts of global oil prices by the International Energy Agency, which now include higher-than-previous forecasts of electric vehicle uptake. For electricity, long-run resource costs feature only minor changes (~0% for road electricity, ~10% decrease for rail electricity), however in the medium-term (2026 to 2032), prices are 10 to 20% higher than previously forecast, driven by a slower decline in prices from the 2023 peak. In terms of Fuel Duty, the freeze on rates in 2023 leads to a long-run decrease of ~7%, given no change in the long-run assumption of RPI-based growth. Fuel Duty for electricity and VAT across all fuel types is unchanged.

The resource cost changes dominate the overall changes in the total pump/retail price of fuel (i.e. inclusive of Fuel Duty and VAT), with large long-run decreases (~20 to 35%) for petrol, diesel and gas oil, and minor increases in the medium term for electricity.

Updated fuel and electricity prices (data book table A1.3.7)

Source: DESNZ

Units: Pence per litre / Pence per kWh – (2010 prices)

Year	Resource cost petrol	Resource cost diesel	Resource cost gas oil	Resource cost electricity road	Resource cost electricity rail	Duty petrol	Duty diesel	Duty gas oil	Duty electricity
2010	42.56	44.30	39.63	11.87	6.88	57.20	57.20	10.99	0.00
2011	52.03	56.23	50.84	12.64	7.13	56.96	56.96	10.95	0.00
2012	53.15	58.13	52.52	13.14	7.79	55.92	55.92	10.75	0.00
2013	51.12	55.77	50.01	13.73	8.53	54.73	54.73	10.52	0.00
2014	45.31	49.67	43.85	14.25	8.69	54.04	54.04	10.39	0.00
2015	32.37	35.00	29.69	13.98	8.77	53.66	53.66	10.31	0.00
2016	30.08	30.74	26.73	13.52	8.58	52.67	52.67	10.12	0.00
2017	36.07	37.66	32.82	14.19	8.93	51.74	51.74	9.95	0.00
2018	41.04	44.20	38.94	15.12	8.92	50.86	50.86	9.78	0.00
2019	40.01	44.36	36.01	16.18	9.67	49.81	49.81	9.57	0.00
2020	30.37	33.46	26.15	15.31	9.51	46.91	46.91	9.02	0.00
2021	42.15	44.20	30.01	16.69	10.89	47.79	47.79	9.19	0.00
2022	64.58	72.55	56.84	24.12	14.98	42.91	42.91	8.25	0.00
2023	53.32	54.32	42.98	26.21	13.85	39.04	39.04	7.51	0.00
2024	48.41	49.27	38.16	24.33	14.00	42.70	42.70	7.63	0.00
2025	45.25	46.01	35.07	22.34	13.26	43.81	43.81	7.70	0.00
2026	45.56	46.28	35.36	21.39	12.41	44.23	44.23	7.77	0.00
2027	44.61	45.32	34.45	19.81	11.34	44.71	44.71	7.85	0.00
2028	44.18	44.88	34.01	18.88	9.97	45.15	45.15	7.93	0.00
2029	43.70	44.39	33.54	18.21	9.66	45.51	45.51	7.99	0.00
2030	42.74	43.43	32.62	17.80	9.43	45.38	45.38	7.97	0.00
2031	42.74	43.43	32.62	17.12	9.56	45.24	45.24	7.95	0.00
2032	42.74	43.43	32.62	16.78	9.34	45.11	45.11	7.92	0.00
2033	42.74	43.43	32.62	16.39	9.11	44.98	44.98	7.90	0.00
2034	42.74	43.43	32.62	16.05	8.84	44.85	44.85	7.88	0.00
2035	42.74	43.43	32.62	16.26	8.94	44.72	44.72	7.86	0.00
2036	42.74	43.43	32.62	15.92	8.96	44.58	44.58	7.83	0.00
2037	42.74	43.43	32.62	15.64	8.60	44.45	44.45	7.81	0.00
2038	42.74	43.43	32.62	15.70	8.65	44.32	44.32	7.79	0.00
2039	42.74	43.43	32.62	15.81	8.67	44.19	44.19	7.76	0.00
2040	42.74	43.43	32.62	15.63	8.63	44.06	44.06	7.74	0.00
2041	42.74	43.43	32.62	15.74	8.67	43.93	43.93	7.72	0.00
2042	42.74	43.43	32.62	15.59	8.82	43.81	43.81	7.70	0.00
2043	42.74	43.43	32.62	15.46	8.72	43.68	43.68	7.67	0.00
2044	42.74	43.43	32.62	15.40	8.76	43.55	43.55	7.65	0.00
2045	42.74	43.43	32.62	15.24	8.69	43.42	43.42	7.63	0.00
2046	42.74	43.43	32.62	14.95	8.59	43.29	43.29	7.61	0.00
2047	42.74	43.43	32.62	14.93	8.56	43.17	43.17	7.58	0.00
2048	42.74	43.43	32.62	14.88	8.91	43.04	43.04	7.56	0.00
2049	42.74	43.43	32.62	14.84	8.90	42.91	42.91	7.54	0.00
2050	42.74	43.43	32.62	15.00	8.84	42.79	42.79	7.52	0.00
2051	42.74	43.43	32.62	15.00	8.84	42.66	42.66	7.49	0.00
2052	42.74	43.43	32.62	15.00	8.84	42.54	42.54	7.47	0.00
2053	42.74	43.43	32.62	15.00	8.84	42.41	42.41	7.45	0.00
2054	42.74	43.43	32.62	15.00	8.84	42.29	42.29	7.43	0.00
2055	42.74	43.43	32.62	15.00	8.84	42.16	42.16	7.41	0.00
2056	42.74	43.43	32.62	15.00	8.84	42.04	42.04	7.39	0.00
2057	42.74	43.43	32.62	15.00	8.84	41.92	41.92	7.36	0.00
2058	42.74	43.43	32.62	15.00	8.84	41.79	41.79	7.34	0.00
2059	42.74	43.43	32.62	15.00	8.84	41.67	41.67	7.32	0.00
2060	42.74	43.43	32.62	15.00	8.84	41.55	41.55	7.30	0.00
2061	42.74	43.43	32.62	15.00	8.84	41.43	41.43	7.28	0.00
2062	42.74	43.43	32.62	15.00	8.84	41.31	41.31	7.26	0.00
2063	42.74	43.43	32.62	15.00	8.84	41.19	41.19	7.23	0.00
2064	42.74	43.43	32.62	15.00	8.84	41.06	41.06	7.21	0.00
2065	42.74	43.43	32.62	15.00	8.84	40.94	40.94	7.19	0.00
2066	42.74	43.43	32.62	15.00	8.84	40.82	40.82	7.17	0.00
2067	42.74	43.43	32.62	15.00	8.84	40.70	40.70	7.15	0.00
2068	42.74	43.43	32.62	15.00	8.84	40.58	40.58	7.13	0.00
2069	42.74	43.43	32.62	15.00	8.84	40.47	40.47	7.11	0.00
2070	42.74	43.43	32.62	15.00	8.84	40.35	40.35	7.09	0.00
2071	42.74	43.43	32.62	15.00	8.84	40.23	40.23	7.07	0.00
2072	42.74	43.43	32.62	15.00	8.84	40.11	40.11	7.05	0.00
2073	42.74	43.43	32.62	15.00	8.84	39.99	39.99	7.03	0.00
2074	42.74	43.43	32.62	15.00	8.84	39.88	39.88	7.00	0.00
2075	42.74	43.43	32.62	15.00	8.84	39.76	39.76	6.98	0.00
2076	42.74	43.43	32.62	15.00	8.84	39.64	39.64	6.96	0.00
2077	42.74	43.43	32.62	15.00	8.84	39.53	39.53	6.94	0.00
2078	42.74	43.43	32.62	15.00	8.84	39.41	39.41	6.92	0.00
2079	42.74	43.43	32.62	15.00	8.84	39.29	39.29	6.90	0.00
2080	42.74	43.43	32.62	15.00	8.84	39.18	39.18	6.88	0.00
2081	42.74	43.43	32.62	15.00	8.84	39.06	39.06	6.86	0.00
2082	42.74	43.43	32.62	15.00	8.84	38.95	38.95	6.84	0.00
2083	42.74	43.43	32.62	15.00	8.84	38.84	38.84	6.82	0.00
2084	42.74	43.43	32.62	15.00	8.84	38.72	38.72	6.80	0.00
2085	42.74	43.43	32.62	15.00	8.84	38.61	38.61	6.78	0.00
2086	42.74	43.43	32.62	15.00	8.84	38.50	38.50	6.76	0.00
2087	42.74	43.43	32.62	15.00	8.84	38.38	38.38	6.74	0.00
2088	42.74	43.43	32.62	15.00	8.84	38.27	38.27	6.72	0.00
2089	42.74	43.43	32.62	15.00	8.84	38.16	38.16	6.70	0.00
2090	42.74	43.43	32.62	15.00	8.84	38.05	38.05	6.68	0.00
2091	42.74	43.43	32.62	15.00	8.84	37.93	37.93	6.66	0.00
2092	42.74	43.43	32.62	15.00	8.84	37.82	37.82	6.64	0.00
2093	42.74	43.43	32.62	15.00	8.84	37.71	37.71	6.62	0.00
2094	42.74	43.43	32.62	15.00	8.84	37.60	37.60	6.61	0.00
2095	42.74	43.43	32.62	15.00	8.84	37.49	37.49	6.59	0.00
2096	42.74	43.43	32.62	15.00	8.84	37.38	37.38	6.57	0.00
2097	42.74	43.43	32.62	15.00	8.84	37.27	37.27	6.55	0.00
2098	42.74	43.43	32.62	15.00	8.84	37.16	37.16	6.53	0.00
2099	42.74	43.43	32.62	15.00	8.84	37.05	37.05	6.51	0.00
2100	42.74	43.43	32.62	15.00	8.84	36.94	36.94	6.49	0.00

Electricity emissions factors

TAG unit A3 (environmental impact appraisal) advises that the impact of transport schemes on greenhouse gas emissions can be estimated by converting estimated fuel/electricity consumption into carbon dioxide equivalent (CO2e) emissions using emissions factors published in the TAG data book (table A3.3). 

The values relating to electricity consumption (for road and rail transport) have been updated to align the values with the latest figures from DESNZ. This includes a change to the relevant parameter for rail, from the long-run marginal generation-based series, uplifted for transmission losses, to the long-run marginal consumption-based industrial series. This change is to align with DESNZ guidance on measuring greenhouse gas emissions per unit of final energy demand. The updated electricity emissions factors figures see long-run reductions compared to the current values, driven by updated DESNZ assumptions on energy production.,

Updated electricity emissions factors (data book table A3.3)

Source: DESNZ

Units: Kg CO2e/kWh

Year	Current (v1.22) electricity roads	Current (v1.22) electricity rail	New (v1.23) electricity roads	New (v1.23) electricity rail	% change electricity roads	% change electricity rail
2010	0.389	0.363	0.389	0.375	0%	3%
2011	0.384	0.356	0.384	0.370	0%	4%
2012	0.377	0.349	0.377	0.364	0%	4%
2013	0.368	0.341	0.368	0.355	0%	4%
2014	0.361	0.333	0.362	0.348	0%	4%
2015	0.351	0.325	0.351	0.338	0%	4%
2016	0.340	0.316	0.340	0.328	0%	4%
2017	0.330	0.306	0.330	0.318	0%	4%
2018	0.319	0.295	0.319	0.307	0%	4%
2019	0.306	0.284	0.307	0.295	0%	4%
2020	0.293	0.272	0.293	0.283	0%	4%
2021	0.279	0.259	0.279	0.269	0%	4%
2022	0.264	0.245	0.264	0.254	0%	4%
2023	0.248	0.230	0.248	0.239	0%	4%
2024	0.231	0.214	0.230	0.222	-1%	3%
2025	0.213	0.197	0.211	0.203	-1%	3%
2026	0.193	0.179	0.191	0.184	-1%	2%
2027	0.172	0.160	0.169	0.163	-2%	2%
2028	0.150	0.139	0.145	0.140	-3%	1%
2029	0.126	0.117	0.120	0.116	-5%	-1%
2030	0.100	0.093	0.093	0.090	-7%	-3%
2031	0.083	0.077	0.071	0.069	-14%	-11%
2032	0.069	0.064	0.055	0.053	-21%	-18%
2033	0.058	0.054	0.042	0.041	-27%	-24%
2034	0.048	0.045	0.032	0.031	-33%	-30%
2035	0.040	0.037	0.025	0.024	-38%	-36%
2036	0.033	0.031	0.019	0.018	-43%	-41%
2037	0.028	0.026	0.015	0.014	-47%	-45%
2038	0.023	0.021	0.011	0.011	-52%	-50%
2039	0.019	0.018	0.009	0.008	-55%	-54%
2040	0.016	0.015	0.007	0.006	-59%	-57%
2041	0.015	0.014	0.006	0.006	-59%	-58%
2042	0.015	0.013	0.004	0.004	-73%	-72%
2043	0.009	0.008	0.003	0.003	-67%	-65%
2044	0.008	0.008	0.002	0.002	-75%	-74%
2045	0.008	0.007	0.001	0.001	-83%	-82%
2046	0.008	0.007	0.001	0.001	-82%	-81%
2047	0.005	0.005	0.001	0.001	-73%	-72%
2048	0.005	0.005	0.002	0.001	-71%	-70%
2049	0.003	0.003	0.002	0.001	-53%	-51%
2050	0.003	0.002	0.001	0.001	-44%	-41%
2050-2100	0.003	0.002	0.003	0.002	0%	4%

Station improvement impacts

TAG unit A5.3 (rail appraisal) provides sources for parameters that can be used to express non-marketed impacts in monetary terms. This includes monetised benefits arising from improvements to rail station facilities, which should follow the principles of journey quality appraisal set out in TAG unit A4.1 (social impact appraisal).

A new version of A5.3, to be released definitively in May 2024, will reflect the latest evidence and best practice in station improvement valuation. Demand uplifts and valuations of station improvements should be applied to all passengers, including those travelling on employer’s business. This is a change to guidance, which had previously recommended the exclusion of business user impacts based upon the cost saving approach to the valuation of travel time. Where this change is expected to have a material impact on appraisal results, analysts should consider the presentation of a sensitivity test to demonstrate the impact of excluding business users.

For the convenience of practitioners, the updated guidance will additionally reference recent evidence on station improvement valuation. Evidence on station improvement valuation does however remain limited, and as such, updated recommendations on the application of values and treatment of uncertainty will also be included in the updated unit.

Wider impacts dataset update

The following inputs in the wider impacts dataset will be updated to include the most recent data from OBR and ONS:

• OBR medium-term forecasts (2024 to 2028) as part of their economic and fiscal outlook (released 06/03/2024).
  • updated values from Annex A.3 determinants of fiscal forecast - including GDP growth, earnings growth, and inflation – these values are mostly broadly similar (and often identical) to the previous figures however now cover a longer forecast period up to 2028 to 2029
• earnings and hours worked, all employees: Annual Survey of Hours and Earnings (ASHE) (released 01/11/2023)
  • this is to replace Cambridge Econometrics forecasts (which were in turn based on ASHE) since we now have ASHE outturn data
• ONS nominal and real gross domestic product, seasonally adjusted £m (released 15/02/2024)
• ONS number of people in employment (aged 16 and over, seasonally adjusted):000s (released 12/03/2024)
• ONS GDP deflator at market prices, and money GDP (released 02/04/2024)

In the dataset we are also including a new row for public sector data. This is because we are exploring the possibility of its inclusion in economic appraisal. The data is based on employment and GVApw data broken down by standard industrial classification (SIC) code from the following sources:

• ONS Business Register Employment Survey – LAD employment and employee count (accessed 25/10/23)
• ONS Annual Population Survey (accessed 16/01/24)
• ONS workforce jobs by industry (SIC 2007) (accessed 12/12/2023)
• ONS Regional gross value added (balanced) by industry: local authorities by ITL1 region (accessed 25/04/2023)

Public sector is defined as that belonging to SIC 2007 codes 84 to 88^{[footnote 1]}. SIC 85 was previously included in the consumer services sector whereas all others were included in the residual (and therefore absent from employment figures in the wider impacts databook). Therefore, there will be an increase in total employment although the employment in consumer services will decrease.

The overall effect brings the data closer in line with the Graham et al (2010)^{[footnote 2]} agglomeration sector definitions which determined the elasticities used in the TAG wider impacts databook.

Contact

For further information on this guidance update, please contact:

Transport Appraisal and Strategic Modelling (TASM) division
Department for Transport
Zone 2/25 Great Minster House
33 Horseferry Road
London
SW1P 4DR

Email: tasm@dft.gov.uk

1. 84: Public administration and defence; compulsory social security, 85: Education, 86 to 88: Human health and social work activities ↩

2. Daniel J. Graham, Stephen Gibbons, Ralf Martin,. The spatial decay of agglomeration economies: estimates for use in transport appraisal (PDF, 322KB). 2010 ↩