Carbon Account for Transport

Chapter 3: Future emissions impact of transport interventions

3.1 Background

This chapter lists those transport interventions, whether devolved or reserved to the UK/EU, which are firm commitments and are expected to have a direct and significant impact on Scottish transport emissions into the future. The interventions are separated between infrastructure projects and those that involve fiscal policy or regulation. Emissions impacts used here are taken from the available project or policy documents, and have been rounded to the nearest 1 kilo-tonne of carbon-dioxide equivalent (ktCO2e) where appropriate.

As well as reporting the emissions impacts, where possible the chapter outlines the general methodological approach for estimating the impact of both infrastructure projects and fiscal/regulatory policies. As independently commissioned projects, the precise estimation methodology may differ significantly depending upon the type of intervention and the modelling approach adopted. Emissions estimates are frequently assessed in isolation, and so will not necessarily include the full interactions between measures or take account of the impact of any future measures on the project. Furthermore, for many interventions there are likely to be a number of localised impacts which may not be captured or presented consistently between appraisals. Where possible, the impacts presented here are the net emissions impact at a national level.

As a result of such methodological variation, the emissions estimates and related timescales are to be used as an informative guide to the direction of change and the order of magnitude only. The comparison, addition or netting off of emissions estimates between interventions or against the GHGI data is not statistically valid and may lead to incorrect conclusions being drawn.

3.2 Infrastructure projects

Undertaken by Transport Scotland and announced by The Minister for Transport, Infrastructure and Climate Change in December 2008, the Strategic Transport Projects Review (STPR) sets out the strategic transport investment priorities for the next twenty years and provides the basis on which Ministers can make informed decisions about future transport spending beyond the current programme. The nature of this publication means that many of the projects will be undertaken at a future date and thus lack a designated timetable and a formal appraisal process. Individual projects from within STPR likely to have a significant emission impact will be included in the CAT commentary as and when they become committed schemes.

Methodology for measuring environmental impacts

Environmental impacts of infrastructure projects are taken from the latest available project documents. In most cases this will be the emissions estimate contained in the project specific Environmental Statement. Some recently announced projects will though not yet have begun a formal appraisal process so have no estimate. For reference, links to the project home page are also provided where an online assessment is available.

STAG recommends that greenhouse gas emissions from road traffic are calculated according to the methodology in the Design Manual for Roads and Bridges[26] (DMRB). DMRB was first introduced in 1992 in England and Wales, and subsequently in Scotland and Northern Ireland. It provides a comprehensive manual system which accommodates current Standards, Advice Notes and other published documents relating to Trunk Road Works.

For emissions associated with the running of diesel and electric trains, STAG recommends the use of the Rail Emission Model Final Report[27] that was produced for the Strategic Rail Authority. This is published on the Department for Transport website, and provides estimated emission factors and detailed data for individual diesel and electric train types.

There are no such established guidelines for estimating carbon estimates for other travel modes. Should such a project arise, the methodology used to estimate the carbon impact is tailored specifically to that individual project. Similarly, it is important to note that when considering the predicted emissions impacts of these infrastructure projects, the modelling procedures used to derive these predictions can differ significantly, particularly in the way in which they account for secondary impacts such as land-use changes resulting from the transport project.


A75 Dunragit Bypass

  • Document: Environmental Statement, Young Associates / Mouchel Parkman
  • Construction completion: March 2014
  • Estimated emissions impact: +4ktCO2e p.a. from 2022

Previously, drivers experienced limited overtaking opportunities along much of the A75, which led to traffic congestion, driving conditions with lower average speeds, increase driver frustration and the potential for accidents. The new scheme comprises an off-line road alignment and, in accordance with its stated objective, provides guaranteed overtaking in both eastbound and westbound directions. The additional CO2e emissions are expected as a result of the increase in distance that vehicles will travel due to the addition of the bypass.

M8, M74 and M73 Motorway Improvements Project

Following award of the contract to Scottish Roads Partnership (SRP) in February 2014, the M8 M73 M74 Motorway Improvements Project is currently well underway and scheduled for completion in Spring 2017. This project bundles together three individual projects: M8 Baillieston to Newhouse, M74 Raith Interchange, and M8 M73 M74 Network Improvements.

SRP anticipate that the project will create in excess of 1,000 jobs in Scotland - the large majority of these jobs are expected to be filled by workers from the local area, similar to the M74 Completion project where 70% of site-based staff came from the local area. The motorway improvements project is expected to reduce the journey time for the 115,000 vehicles that use the busiest sections of the M8 each day.

It is predicted that the scheme will lead to a reduction of more than 100 accidents per year and more freely flowing traffic on these strategic routes will reduce the emissions associated with queuing traffic and improving both air quality and health.

M74 Raith Interchange

  • Document: Environmental Statement (2007), Mouchel Fairhurst JV
  • Anticipated construction completion: 2017
  • Estimated emissions impact: +10ktCO2e p.a. from 2017; +10ktCO2e p.a. from 2020

The scheme is aligned with the M8 Baillieston to Newhouse works and the Associated Network Improvements. These are vital links in the trunk road network of Central Scotland and serve substantial existing developments as well as some of the most significant future development sites in Scotland.

Severe traffic problems exist at Raith Junction due to the interaction of heavy turning volumes from the A725 and the M74 at the signalised roundabout. This scheme aims to relieve traffic congestion at the junction creating free-flow conditions on the A725.

M8 Associated Network Improvements

  • Document: Environmental Statement, 2008 (Mouchel Fairhurst JV)
  • Anticipated construction completion: 2017
  • Estimated emissions impact: +2ktCO2e p.a. by 2020

This scheme comprises capacity improvements on sections of the M73, M74 and M8 adjacent to Baillieston and Maryville interchanges as a result of changes to east-west traffic patterns following completion of the M74 and once improvements to the M8 are in place. The scheme will be procured as a package with the M8 Baillieston to Newhouse Scheme and M74 Raith Junction.

M8 Baillieston-Newhouse

  • Document: Environmental Statement (2007), Mouchel Fairhurst JV
  • Anticipated construction completion: 2017
  • Estimated emissions impact: +30ktCO2e p.a. from 2017; +30ktCO2e p.a. from 2020

This project is a proposal to upgrade the existing A8 between Baillieston and Newhouse to dual three-lane motorway standard equivalent.

The DMRB was used to calculate the change in greenhouse gas emissions, therefore the assessment has included all traffic on the entire modelled network, in addition to links that were explicitly included in the local assessment. The increase in emissions is due to an increase in predicted traffic levels.

A90 Aberdeen Western Peripheral Route (AWPR) and A90 Balmedie-Tipperty

  • AWPR Document: Assessment of Effects of Updated Traffic Model submitted for PLI (2008), which updates previous source of 2007 Environmental Statement, Jacobs
  • Balmedie - Tipperty Document: Environmental Statement (2007), Grontmij / Natural Capital
  • Anticipated construction completion: It had been hoped to start construction of the AWPR in 2011 however, legal challenges submitted to the Court of Session challenging the decision to proceed with the project will delay construction until resolution of the challenges. AWPR has now been combined with B-T to form one project.
  • Estimated emissions impact for AWPR: +8ktCO2e p.a. from 2012; +10ktCO2e p.a. from 2027. For Balmedie- Tipperty : +2ktCO2e p.a. from 2010 (assumed opening year in environmental statement)

A peripheral route around Aberdeen is proposed to reduce the high volumes of traffic using the A90 in the centre of Aberdeen, and to reduce the traffic congestion that the city experiences as a result of the volume of traffic using the A90 and its associated radial roads. The overall increase in the number of road vehicles, however, is expected to lead to an increase in carbon dioxide emissions.

The AWPR will provide substantial benefits across the whole of the North East of Scotland and will provide a boost to the economy; increase business and tourism opportunities; improve safety; cut congestion as well as increasing opportunities for improvements in public transport facilities.

This proposed dualling of the A90 between Balmedie and Tipperty will provide continuous dual carriageway between Aberdeen and Ellon, which will remove the bottleneck caused by the existing single carriageway. The local community has been pressing for this upgrade for a number of years. The increase in emissions through Balmedie -Tipperty is mainly due to the increase in the road sections that make up the total road network assessed.

Forth Replacement Crossing

The Forth Replacement Crossing (FRC) is a major road infrastructure project being delivered by Transport Scotland. The project was driven by uncertainty over the future viability of the existing Forth Road Bridge, and is designed to safeguard this vital connection in Scotland's transport network. It comprises a new cable-stayed bridge across the Firth of Forth (the Queensferry Crossing), to the west of the existing Forth Road Bridge, and associated new and improved road infrastructure to the north and south of the bridge. The scheme will retain the existing Forth Road Bridge as a public transport corridor for use by buses, taxis and other specified users and for continued use by pedestrians and cyclists. The Queensferry Crossing will be used by all other traffic including private cars and heavy goods vehicles. Emergency vehicles will be able to use either bridge.

The FRC was identified as a key strategic investment project in Scotland's national transport network in the Strategic Transport Projects Review (STPR) undertaken by Transport Scotland in December 2008, and the National Planning Framework (NPF2) published by the Scottish Government in June 2009. There are eight specific transport planning objectives for the FRC which have underpinned the work on the project. These are to:

  • maintain cross-Forth transport links for all modes to at least the level of service offered in 2006
  • connect to the strategic transport network to aid optimisation of the network as a whole
  • improve the reliability of journey times for all modes
  • increase travel choices and improve integration across modes to encourage modal shift of people and goods
  • improve accessibility and social inclusion
  • minimise the impacts of maintenance on the effective operation of the transport network
  • support sustainable development and economic growth
  • minimise the impact on people, and the natural and cultural heritage of the Forth area.

Construction commenced in 2011 and the FRC remains on target to open late 2016.

Dualling of A9

  • Document: Environmental Statement: not yet available
  • Anticipated construction completion: 2025
  • Estimated emissions impact: not yet available

This programme will address issues of driver frustration on the A9 caused by the limited guaranteed overtaking opportunities that current exist, resulting in improved connections between Perth and Inverness. Options for the proposed dual carriageway are currently being developed but it is likely that it will largely comprise on-line widening due to the environmental and physical constraints in the corridor.

It is too early to say how CO2e emissions may change as a result of the scheme. Design development work is now underway and the emerging findings are that the dualling will increase emissions as a consequence of changes to vehicle speeds. Quantification of that impact across the programme is not yet available and a number of route options are still being assessed. Quantification will take place as part of the preparation of the Environmental Statements for the component projects.

Dualling of A96

Document: Environmental Statement: not yet available

  • Anticipated construction completion: 2030
  • Estimated emissions impact: not yet available

This programme will address issues of driver frustration on the A96 caused by the limited availability of overtaking opportunities. It will also address issues of community severance by introducing bypasses to communities along the route. Both objectives will serve to improve connectivity between Inverness and Aberdeen. Baseline information and constraints mapping is currently being collated to support future option development for the proposed dual carriageway.

Given the likelihood of extended lengths of dual carriageway to provide bypasses it is likely that CO2e emissions will increase as a result of the scheme. However further work will be undertaken during the design development to understand changes to vehicle speeds and their consequences for emissions before and after the scheme is in place.


Borders Railway

  • Document: Borders Railway Design Development Appraisal (2008), Transport Scotland
  • Construction complete - Borders Railway operational as of 6/9/2015
  • Estimated emissions impact: Cumulative impact of 32ktCO2e by 2030, 2ktCO2e by 2050 and -29ktCO2e by 2070[28].

This project has reinstated part of the former Waverley rail route from the Scottish Borders to Edinburgh.

The change in CO2e emissions has been calculated in line with STAG guidelines. For road traffic, the calculations are based on changes to the number of car journeys between the different stations, with each journey modelled separately. The emissions from the railway have been calculated in line with the Rail Emissions Model produced by the Strategic Rail Authority.

Overall, the Borders Railway Project will have a beneficial impact on CO2e levels but most recent assessments suggests that it will see a small net increase in emissions in the early years before removing approximately 29ktCO2e over the appraisal period to 2070.

Edinburgh-Glasgow (Rail) Improvements Programme

  • Document: Edinburgh Glasgow Improvement Programme (EGIP) Appraisal and Analysis Model (2013), Transport Scotland
  • Anticipated construction completion: Phased to 2016
  • Embodied carbon emissions: +112ktCO2 (Phase 1 only) or +157ktCO2 (Phase 1&2) from construction and rolling stock provision
  • Operational emissions[29] :
  • Average annual savings of -28ktCO2 (Phase 1 only) or -30ktCO2 (Phase 1&2) p.a. from 2017
  • Cumulative savings of:
    • -234ktCO2 (Phase 1 only) or -236ktCO2 (Phase 1&2) by 2025.
    • -946ktCO2 (Phase 1 only) or -995ktCO2 (Phase 1&2) by 2050.
    • -1,743ktCO2 (Phase 1 only) or -1,843ktCO2 (Phase 1&2) by 2075.

This intervention was identified early in the STPR and brought forward in a study which considered improvements to the capacity, frequency and journey time of rail services between Edinburgh and Glasgow.

The change in CO2e emissions has been calculated in line with guidance from the Department for Energy and Climate Change. Previous estimates derived from the Network Modelling Framework (NMF) have been significantly revised to reflect the latest operational assumptions for the programme. There is estimated to be a reduction in road emissions of around -3ktCO2e p.a. which is included in the overall figures presented.

The Edinburgh Glasgow Improvement Programme is expected to result in a significant reduction in emissions, through the electrification of approximately 350 km of single track and the resulting move from diesel to electric trains. The programme therefore achieves its emissions reductions reported here through transferring emissions from the non-traded sector to the traded sector, as demonstrated in the table below. If electricity emissions and those from embodied carbon are included, the total net impact of EGIP is -1,116 (-1,114 for Phase 1 only) ktCO2e by 2075. Of this total, -1,669 ktCO2e arises from diesel savings from trains removed from the network (same value for Phase 1 only), -174 (-74 for Phase 1 only) ktCO2e from cars removed from the road network, and +570 (518 for Phase 1 only) ktCO2e from the new electric trains added to the network. Table 4 demonstrates the precise breakdown of the emissions impact across the different sectors.

Aberdeen to Inverness

  • Document: Not yet available
  • Environmental Statement: not yet available
  • Anticipated construction completion: In phases through to 2030
  • Estimated emissions impact: not yet available

This project will deliver significant journey time improvements and greater connectivity for both passenger and freight services operating on the Aberdeen to Inverness rail corridor. It is too early to say how CO2e emissions may change as a result of the improvement project. Further work will be undertaken during the design development to understand the impact the increased frequency and additional services will have on emissions following their introduction.

Highland Mainline

  • Document: Not yet available
  • Environmental Statement: not yet available
  • Anticipated construction completion: In phases through to 2025
  • Estimated emissions impact: not yet available

This project will deliver significant journey time improvements and greater connectivity for both passenger and freight services operating between Inverness and the Central belt. It is too early to say how CO2e emissions may change as a result of the improvement project. Further work will be undertaken during the design development to understand the impact the increased frequency and additional services will have on emissions following their introduction.

Table 5: Change in emissions from EGIP (Phase 1&2, 'Phase 1 only' impact in brackets) by sector (ktCO2e)

Operational Embodied**
Budget Period Transport
Non-transport sector*
2013 - 2017 -17 (-17) +16 (+16) +105 (+105)
2018 - 2022 -132 (-132) +129 (+129) +7 (+7)
2023 onwards -1,694 (-1,595) +425 (+373) +46 (+0)
UK Net -1,843 (-1,743) +570 (+518) +157 (+112)

* Electricity production and distribution sector
** Primarily manufacturing and construction

Table 6: Estimated net emissions impact of individual transport infrastructure projects

Project title Published emissions estimate
A75 Dunragit Bypass +4 ktCO2e p.a. from 2022
M74 Raith Interchange +10 ktCO2e p.a. from 2020
M8 Associated Network Improvements +2 ktCO2e p.a. by 2020
M8 Baillieston-Newhouse +30 ktCO2e p.a. from 2020
A90 Balmedie-Tipperty +2 ktCO2e p.a. from 2013
A90 Aberdeen Western Peripheral Road +10 ktCO2e p.a. from 2027
Forth Replacement Crossing +20 ktCO2e p.a. in 2032
Stirling-Alloa-Kincardine Railway Line +2 ktCO2e p.a. from 2009
Borders Railway +32 ktCO2e total by 2030
+2 ktCO2e total by 2050
-29 ktCO2e total by 2070
Edinburgh-Glasgow (Rail) Improvements Programme -28 ktCO2e average p.a. from 2017
-1843 ktCO2e total by 2075
+167 ktCO2e p.a. from 2031

The emission estimates within this table are forecast changes in carbon dioxide emissions with the project compared to without the project in a given future assessment year. These estimates have been calculated using a variety of methodologies and, consequently, it is not statistically valid to aggregate the individual figures or directly compare them with one another.

3.3 Fiscal / regulatory measures

The current split between devolved and reserved powers means that the majority of fiscal and regulatory decisions that impact on Scottish transport emissions are taken at either the UK or EU level.

Those areas over which Scottish Ministers have direct control are though still extremely important for Scottish emissions, particularly in respect of behaviour change, a vital component of long term emissions reductions, and the removal of certain key barriers that could affect the significant uptake of ultra-low or zero carbon vehicles by households.

Published in June 2013, the Second Report on Proposals and Policies provides the most up to date and comprehensive analysis and assessment of these Scottish policies and the potential impact these measures can have on emissions out until 2027[30]. The impact of tightening EU car and van emissions standards and the Renewable Fuels Transport Obligation are also covered within the RPP's analysis.

With a narrower focus on road transport emissions, and particularly on the transition from reliance on fossil-fuelled vehicles towards plug-in cars and vans, Switched on Scotland[31] sets out the necessary steps and barriers to be overcome on the pathway to the almost complete decarbonisation of road transport.

It is more difficult to ascertain the potential emissions impact in Scotland from UK and (other) EU fiscal or regulatory measures, not least because the impacts are analysed and estimated at a more aggregate level. That said, some Scottish estimates have been generated and where available these are recorded below alongside the description of the policy intervention.

The best and most readily available sources of information for the remaining aggregate UK emissions impacts include published Impact Assessments, associated documents accompanying the annual HM Treasury (HMT) Budget and Autumn Statement/Pre-Budget reports, HMRC notes and the House of Commons Library for more general topic background and briefing.

Air Passenger Duty (APD)

Key documents and analysis:

Air passenger duty (APD) is charged on all passenger flights from almost all UK airports[32]. The rate of tax varies according to passenger destination and the class of passenger travel. Between 1 2009 and 2014 APD was been structured around four distance bands, set at intervals of 2,000 miles from London. Since 2013 APD rates have been increased in line with inflation.

The 2014 Budget announced the merging of highest APD bands (B, C and D) so that any flight to a country with a capital city more than 2000 miles from London would now be charged at the current Band B rate. Very few current direct flights from Scotland are affected by this simplification of the banding structure. This change is estimated in increase annual UK emissions by 0.3 MtCO2e but is unlikely to have a material impact on Scottish emissions.

More recently, Transport Scotland has published its assessment of the likely impact on emissions following a reduction in APD in Scotland. This work used Scottish information and data wherever possible and also checked the result against the earlier UK analysis. This analysis suggests that cutting APD by 50% in Scotland would lead to an annual increase in Scottish emissions of 0.05 MtCO2e to 0.06 MtCO2e[33].

In May 2015 children under 12 travelling in the lowest class of travel became exempt from APD, and from March 2016 an extension is planned to include children up to the age of 16 in this exemption. The impact at the UK and Scottish level on demand and the economy more generally is expected to be negligible.

Inclusion of aviation in EU ETS

Key documents and analysis:

  • Implementation date: 2010
  • Estimated emissions impact: up to - 183 MtCO2e p.a. in 2020 across Europe relative to no cap

Following a Commission proposal in December 2006, a directive was adopted that required all operators flying into or out of aerodromes in the European Economic Area (EEA) to monitor annual carbon emissions, to report them and to surrender the corresponding number of carbon allowances.

The Aviation Greenhouse Gas Emissions Trading Scheme Regulations 2010 came into force in the UK on 31 August 2010. The inclusion of aviation within the emissions trading system allowed the sector to take responsibility for its carbon emissions in the most cost effective way. While it is difficult to predict the exact impact of the scheme, particularly with the ongoing economic uncertainties, earlier estimates made by the Commission suggest that the aviation cap could reduce emissions in 2020 by up to 183 million tonnes CO2e.

In the face of international opposition to the Directive the European Commission announced in November 2012 that it would "Stop the Clock" on the implementation of the "international" aspects of the Aviation Emissions Trading System in an effort to facilitate a global based trading system through the International Civil Aviation Organisation (ICAO). The effect of the Commission's action is that only flights between EAA aerodromes need comply with the Aviation ETS at this time. The impact of this revision on the Commission's original assessment of emissions reductions is unclear but the revision is unlikely to have any material effect on the impact of the regulation on Scottish aviation emissions as the majority of flights from Scotland are within the EEA.

Fuel duty

Latest documents and analysis: Budget March 2015:

  • Estimated emissions impact: +0.2 MtCO2e per year, +0.3 MtCO2e (UK).

Due to high oil prices, Budget 2011 cut the fuel duty by one penny per litre and since then all increases in fuel duty have been cancelled. Up until 2014, the cancellation of these fuel duty rises has been estimated to add 0.5 MtCO2e per annum to the UK emissions total compared to where it would otherwise have been. It should be noted that this assessment does not take account of the dampening effect of the rise in wholesale fuel prices and therefore pump prices on demand, or the continued freeze in duty announced in the March 2015 budget.

From 31 May 2015 the Rural Fuel Rebate allowed customers in certain rural post codes to benefit from a cut of 5 pence per litre in the fuel price. Thirteen of the seventeen named post codes eligible for this cut are in Scotland, eleven in Highland and two in Argyll and Bute. These cuts would be expected to lead to a negligible increase in emissions.

Reform to vehicle excise duty

Latest documents and analysis:

  • Budget 2015 HMRC documentation
  • Estimated emissions impact of 2010 change: -0.9 MtCO2e by 2020
  • Estimated impact of 2017 proposal:- not quantified

In April 2010, the Government introduced a new first-year rate of VED. Under this system, all cars emitting up to 130 g CO2e per km paid no VED in the first year. Cars emitting over 165 g CO2e per km paid additional VED in the first year. First year rates were introduced to encourage the purchase of more fuel-efficient cars. Together, these changes are estimated to result in a cumulative UK emissions saving of 0.9 MtCO2e by 2020. Subsequent budgets increased VED rates by inflation but froze HGV rates.

In 2017 a new VED banding system will be introduced. First year rates for newly registered cars will depend on CO2 emissions. Thereafter all but zero emitting vehicles will pay £140 with a 5 year supplement of £310 for cars costing over £40,000. This is likely to have an initially small but negative impact on the emissions outcome with all but zero rated cars in 2017 seeing an increase in VED over their existing equivalent makes and models. The reverse is true for more polluting cars as newer cars will see a reduced rate of VED.

Company car tax

Latest documents and analysis:

  • Anticipated implementation date: Ongoing
  • Estimated emissions impact: Not quantified

The UK Government's June 2010 budget set out to reform company car tax and provide incentives to purchase the lowest emitting vehicles on the market. This has been reinforced in subsequent budgets to incentivise the purchase and manufacture of ultra-low emission vehicles in the UK. Budget 2013 set out rates for company cars emitting 75g CO2e per km or less from 2016-17 onwards and provides a commitment that in 2017-18 there will be a 3 percentage point differential between the 0-50 and 51-75 g/km CO2e bands and between the 51-75 and 76-94 g/km CO2e bands. The 2014 budget further lifted the percentage of a company car list price that would be subject to tax for cars emitting more than 75 g CO2e /km.

This policy aims to encourage the purchase of ULEVs and hence contribute to the objectives of reducing greenhouse gas emissions from road transport. However, given that the market is at an early stage of development it is not possible to precisely estimate the impact on ULEV sales or emissions savings. That said the savings are likely to be small to begin with.

Fuel benefit charge (FBC)

The provision of free fuel to company car drivers provides a perverse environmental incentive. The aim of the fuel benefit charge is to tax this benefit as though it were income. The figure on which the calculation is based rises each year and for cars currently stands at £22,100. The van fuel benefit charge - on which tax on free van fuel is payable - stands at £594. The Government has committed to pre-announcing the FBC multiplier one year in advance.

Table 7 summarises the previous information. As with Table 6, these emissions estimates are not produced using a single, consistent methodology so are not directly comparable.

Table 7: Net emissions impact estimates of fiscal / regulatory measures

Project title Published emissions estimate
Air passenger duty i) -0.3MtCO2e p.a from 2015-16 (UK)
ii) +0.05 MtCO2ep.a in Scotland from 50% cut in APD
Inclusion of aviation in EU ETS -183MtCO2e* p.a. in 2020 (Europe)
Fuel Duty +0.5 MtCO2e p.a. by 2013 from two freezes (UK)
Negligible impact from Rural Fuel Rebate
Reform of Vehicle Excise Duty[34] -0.9 MtCO2e total savings by 2020 (UK)
2017 proposal - impact not quantified
Company car tax Not quantified
Fuel benefit charge Not quantified
RPP2 - Decarbonising Vehicles -2.5 MtCO2e in 2027
RPP2 - Sustainable Communities -0.3 MtCO2e in 2027
RPP2 - Business Transport Measures -0.5 MtCO2e in 2027
RPP2 - Network Efficiencies <-0.1MtCO2e in 2027
RPP2 - Additional Measures -0.75 MtCO2e in 2027

The emission estimates within this table are forecast increases or decreases in carbon dioxide emissions with the policy compared to without the policy in a given future assessment year. These estimates have been calculated using a variety of methodologies and, consequently, it is not statistically valid to aggregate the individual figures or directly compare them with one another.

* Estimate from before the introduction of 'Stop the Clock' - see relevant section in EU ETS above

3.4 Projected net emissions impact from Scottish projects

The Carbon Account for Transport collates information from a variety of sources and outputs with one of the key sources being the findings generated from the application of the Scottish Transport Appraisal Guidance (STAG) to transport proposals. Two key concepts in STAG are that an appraisal:

  • should be applied proportionately but comprehensively. The whole process should be used and the level of detail required will be determined by the scale of the impacts of the transport issue being addressed.
  • should not prioritise between options. Instead, it is an aid to decision makers in order to make more informed choices. STAG may provide an initial rationale for investment and it is important that the STAG outcomes are revisited as the Business Case for an intervention develops.

As such, a study undertaken using STAG is not required to provide an absolute prediction of all of the outcomes of an intervention. Instead, it provides sufficient information to understand the relative impacts between different options. The individual results cannot therefore simply be summed to produce an aggregate impact.

While these assessments provide one of the key purposes of the CAT - to improve transparency - something further is needed to monitor progress towards the NTS strategic outcome of reduced transport emissions. In 2010 a single model run of the Land-Use and Transport Integration in Scotland (LATIS) service was commissioned to estimate the net impact of all measures within the CAT that fall under the competence of the Scottish Government or other Scottish public body[35]. LATIS includes a strategic transport and land-use model covering all of Scotland and all motorised modes of transport so the use of LATIS to assess the carbon impacts of Scottish transport schemes ensures network consistency and takes full account of the potential displacement of developments between one area and another. The modelling of this set of projects over the timescale of their introductions also provides a greater understanding of the full impact that Scottish interventions are having, or are expected to have, on underlying emissions from transport. The model is not a complete assessment of the likely impact as it does not include the impacts of those measures taken at a reserved level - for example changes to fuel duty or some of the demand side measures outlined in RPP2.

The updating of the baseline data within LATIS enabled a revised set of projections to be run 'with' and 'without' the identified infrastructure projects over which Scotland has direct control. The latest estimates from the revised projection are shown in Table 8. The table shows that the combined impact of the projects generates a small increase in overall emissions, with the long-run impact estimated at an additional 50 ktCO2e p.a. by 2027. This is equivalent to an additional 0.4% on annual transport emissions in 2027 relative to where emissions would otherwise have been.

Table 8: Projected net emissions impact of Scottish projects[36]

Year Annual Change in Emissions (ktCO2e)
2017 30
2022 30
2027 50