7. Emissions Impact of Transport Interventions

Carbon Account For Transport Volume 9, 2017

7. Emissions Impact of Transport Interventions

This chapter examines the emissions arising from infrastructure projects and policies expected to impact Scottish transport emissions in the future. 

7.1 Infrastructure Projects

As each project is independently commissioned, the exact methodology used to estimate the emissions impact may differ, depending on the type of intervention and the modelling approach adopted.  Furthermore, emissions estimates are frequently assessed in isolation, and therefore do not consider any interactions between measures and resulting emissions. There are also likely to be local impacts which may not be captured or presented consistently between infrastructure projects. Where possible, the net impacts at a Scottish level are presented. Because of these variances, the impacts presented are intended only to inform the direction and order of magnitude of the resulting change in emissions. In most cases, the impact quoted is from the project specific environmental statement. Note that comparisons between these impacts and the published NAEI data are not statistically valid, and may lead to incorrect conclusions being drawn.

7.1.1 Methodology

Scottish Transport Appraisal Guidance (STAG) recommends that greenhouse gas emissions from road traffic are calculated according to methodology in the Design Manual for Roads and Bridges (DMRB). This is a comprehensive manual which accommodates current standards, advice notes and other published documents relating to trunk road works.

For rail projects, STAG recommends using the Rail Emissions Model Final Report produced for the Strategic Rail Authority. It contains the estimated emissions factors for different models of diesel and electric trains.

No established guidelines exist for other travel modes.

7.1.2 Emissions Impacts

The projects and their respective emissions impacts are shown in the table below. Details of each project are shown through the hyperlinks in the table. The emission estimates are forecast changes in greenhouse gas emissions with the project compared to without the project in a given future assessment year or in aggregate in the case of the Edinburgh to Glasgow (Rail) Improvement Project. 

Figure 20: Estimated emissions impacts of infrastructure projects
Project title  Published emissions estimate 
M74 Raith Interchange  +10 ktCO2e p.a. from 2020 
M8 M73 and M74 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 2010[19] 
A90 Aberdeen Western Peripheral Road  +10 ktCO2e p.a. from 2027 
Forth Replacement Crossing  +20 ktCO2e p.a. in 2032 
Edinburgh-Glasgow (Rail) Improvements Programme  -33 ktCO2e from 2017[20]

Sources: Assessments of individual projects

7.2 Fiscal and Regulatory Measures

Certain fiscal and regulatory measures have the potential to impact greenhouse gas emissions from transport, though the Scottish Government has limited influence on many of them because the majority are reserved to either the UK Government or the European Union. However, Scottish Ministers still have considerable autonomy over many other policies which can affect greenhouse gas emissions, particularly in regards to behavioural changes and mode switching to lower or zero emitting modes.

The Climate Change Plan, due to be published in early 2018, will provide an up to date and comprehensive analysis of policies under the jurisdiction of The Scottish Government, and their impact on emissions out to 2032.

The measures for which impact assessments have been conducted are:

  • Air Departure Tax: this is the Scottish replacement to Air Passenger Duty, which is a tax levied on seats departing from UK airports. It is set by the UK Government. The new tax is set by The Scottish Government, and is levied on flights departing from Scottish airports only. The Scottish Government wishes to reduce the overall burden of the tax by -50%, which is expected to increase demand for air travel.
  • Inclusion of aviation in European Union Aviation Emissions Scheme: these are regulations which came into force in the UK in 2010. Under the regulations, each airline operating in Europe receives a tradable allowance covering a certain level of emissions each year. They are required to monitor, report and verify their emissions, and to surrender allowances against them. This allows the aviation sector to take responsibility for its greenhouse gas emissions in the most cost effective way.
  • Fuel Duty: this is a tax levied on petrol, diesel and other hydrocarbon based fuels. Due to high oil prices, the 2011 budget cut fuel duty by 1 penny per litre. All subsequent planned rises have been cancelled. 

There are also some policies which are likely to impact emissions which have not been quantified in analysis. These are:

  • Vehicle Excise Duty: from 1st April 2017, the first year rates for newly registered cars will be determined by emissions levels. Thereafter petrol or diesel cars are charged £140 per year, alternative fuel[21] cars are charged £130, and electric vehicles are not charged. Cars with a retail price exceeding £40,000 pay a higher annual rate. The emissions impact is not quantified, but the UK Government website states “by strengthening the incentive to purchase zero-emission cars and ULEVs over conventionally fuelled cars this measure is expected to contribute to the UK's carbon emissions targets”[22]
  • Company car tax: the June 2010 budget introduced measures to make this tax more favourable to lower emitting cars. These have continued to be revised in subsequent budgets.
  • Fuel Benefit Charge: the provision of free fuel to company car drivers results in a perverse environmental incentive. The aim of the fuel benefit charge is to tax this benefit as though it were income by calculating the personal benefit a car gives to its user(s). The charge for a car in 2017/18 is £22,600. The amount paid is a percentage of this amount which depends on the emissions per kilometre of the car. A more lenient scheme is in operation for vans. 

The table below shows the impact of measures with quantified impacts affecting Scotland at the time of publication.

Figure 21: Estimated emissions impacts of fiscal and regulatory measures
Project title  Published emissions estimate 
Air Departure Tax (currently Air Passenger Duty UK wide) Maximum +104.8 kt CO2e in 2021 as a result of a -50% reduction across all bands.
Inclusion of aviation in EU ETS  -183 Mt CO2e* p.a. in 2020 (across Europe) 
Fuel Duty  +0.5 Mt CO2e p.a. by 2013 from two freezes (UK) 

Negligible impact from Rural Fuel Rebate 

Sources: Various – see hyperlinks.