Supplementary memorandum submitted by
the Department for Transport
This memorandum responds further to the Committee
Session of 14 June where the Secretary of State for Transport
14 JUNE HEARING
A. What is the impact on carbon emissions
of the road schemes that are being built, in particular for the
35 major road schemes built since 2001 and the M6 Toll road? How
this was calculated?
1. Our modelling suggests the impact to
be significantly less than 0.15 million tonnes of carbon (MtC).
2. The impact on carbon emissions is estimated
at different levels of detail. Modelling provides a strategic
assessment of the impact of the roads programme, whilst appraisal
provides more localised information on individual schemes.
3. The National Transport Model is a multi-modal
surface transport model. It covers walking, cycling, bus, rail,
light rail, cars, vans and lorries. It can provide estimates of
the effect on each mode and on emissions of CO2, NOx
and PM10. It has considerable detail on the household composition,
area type, road type and time of day. It can show the effect of
changes to policies and other inputs, including on capacity and
prices. Details of the model can be found at: http://www.dft.gov.uk/stellent/groups/dfteconappr/documents/divisionhomepage/030708.hcsp
4. Results from the model have suggested
that Highways Agency road improvements, as assumed in our modelling
for the Future of Transport White Paper, would add around 0.16
MtC in 2010 for Great Britain. The equivalent figure for England
is around 0.15 MtC.
5. Modelling of 45 schemes in the Highways
Agency Targeted Programme of Investment (TPI) in 2000which
includes 31 of the 35 schemes completed since 2000suggests
these schemes would add around 0.03 MtC in 2010.
6. The relatively small impact reflects
two conflicting results of road investment. Enhanced capacity
reduces congestion and can improve the fuel efficiency and reduce
emissions of vehicles. However there will be some increase in
traffic levelsaround ½% in 2010which off-sets
7. In addition, these figures need to be
seen in context. In particular, the modelling performed for the
Future of Transport White Paper in 2004 suggested that (in the
absence of the SR04 road programme and other transport policies)
carbon emissions from transport would increase by nearly 3 million
tonnes between 2000 and 2010. The main drivers of this increase
were a growth in freight traffic and assumed increases in population
and incomes leading to an increase in distance travelled by car.
8. Recent modelling also suggests that other
transport policies (eg sustainable distribution, public transport
investment and smarter travel choice measures) would reduce annual
emissions from surface transport by 0.8 MtC between 2000 and 2010. More
recently we have announced the Renewable Transport Fuels Obligation
that is expected to reduce emissions in the UK by a further 1.6
MtC by 2010 (though only a net global reduction of 1MtC, once
production abroad and transport of the fuel is taken into account).
Consequently the modelled impact of road schemes on carbon emissions
is rather small in comparison to "background growth"
and the total savings that we expect to achieve through other
9. An alternative method of calculating
the impact of the 35 schemes would be to sum the carbon impacts
of individual schemes according to their estimated impacts as
detailed in each appraisal. Appraisal allows a more detailed assessment
of the economic, social and area specific environmental impacts
of a particular scheme. However, this may not give an accurate
picture of the total emissions from all schemes, as the interaction
between individual schemes may not be taken into account in appraisals.
Strategic modelling as described above, looks at cumulative impacts
across the network and therefore gives a more accurate aggregate
10. There have been several significant
developments in the Department's approach to appraisal since the
11. In 1998 the New Approach to Appraisal
(NATA) was introduced which provided a consistent and compulsory
framework to the assessment of environmental and social impacts.
In particular it made the assessment of carbon impacts compulsory.
12. Prior to this, the assessment of carbon
was not always completed, nor was it always consistent. For example
the M6 Toll Road went to public enquiry in 1994/5. As such
the appraisal information was completed prior to the introduction
of NATA. A technical paper written in 1994 suggested the new road
would reduce carbon emissions by 0.01 to 0.02 MtC. Our
methodology for calculating carbon dioxide has much improved for
schemes coming forward now.
13. Twenty seven of the schemes completed
since 2000 undertook statutory planning procedures prior to the
introduction NATA. A New Deal for Trunk Roads in England: Understanding
the New Approach to Appraisal estimated carbon impacts for
twenty of these schemes. These are summarised in the table below.
Additional Carbon Dioxide Emissions (tonnes)
Number of Schemes 0-2000 18 2000-5000 1 5000+ 1
14. Since 1998, appraisal methodology has continued
to improve, reflecting scientific and other advances. Schemes
now have more precise estimates of the carbon impact. A total
of eight schemes completed since 2000 have these more detailed
estimates, and are outlined at Annex A.
15. Two of these schemesthe M4 Junction
18 and M5 at Hallen Hillhave been assessed under the latest
value for money process; which provides a single assessment of
the economic, social and environmental implications of the schemes.
16. The Department continues to refine and
improve the appraisal process and the way it is used to advise
decisions. Further guidance on the assessment of carbon impacts
is currently being prepared.
17. The Committee Clerk followed up the
14 June evidence session with some further questions, which are
set out below with the Government's response.
B. In the context of saying that the RTFO
will achieve the equivalent of taking a million cars off the road,
what is the basis on which DfT calculates the average carbon emissions
per car per year (ie what are the factors you usepresumably,
average miles per year, average fuel consumption per mile, and
average carbon emitted per litre of fueland the values
you give for each).
18. A thorough economic analysis has been
undertaken to estimate the impact in terms of carbon savings,
costs and benefits of the RTFO. This estimated that the RTFO would
result in net carbon savings in the region of 1MtC (million tonnes
of carbon) in 2010.
19. As an illustration of what this means
in terms of carbon emissions from cars, we carried out a calculation
Take average fuel efficiency of a
car on the road today (around 180g CO2/km)
Multiply by average annual mileage
(eg 15,500 km) to give average CO2 emissions from a
car over a typical year. 15,500 x 180 = 2.79 tonnes CO2
Multiply by 12/44 to convert CO2
to carbon = 760,909 g C.
20. Therefore, since the average car emits
something like 0.76 tonnes of carbon a year, saving a million
tonnes of carbon is the equivalent of taking at least a million
cars off the road. Alternatively on this basis a million tonnes
of carbon is equivalent to taking about 1.3 million cars of the
road, thus our estimate of one million cars is cautious.
C. What is DfT's methodology for calculating
the likely net effect on carbon emissions? How is this impact
taken into account, within appraisals of major transport proposals
(eg those costing more than £5 million)
21. DfT's approach to appraising the costs
and benefits of transport schemes is consistently applied across
all modes since the introduction of a New Approach to Transport
Appraisal in 1998. The guidance for this process is available
22. Proposed road schemes are subject to
a detailed assessment which looks at their impacts on the environment,
the economy, road safety, accessibility and integration. These
five objectives have several sub-objectives against which the
schemes are assessed. The impact of a transport scheme on greenhouse
gas emissions is one of 10 environmental sub-objectives that are
23. The basic appraisal method is the same
across modes and is set out in Webtag (see the link above). Estimates
of carbon dioxide emissions are made for a base year (current
year), the opening year of the scheme without the scheme in place,
and the opening year of the scheme with the scheme in operation.
24. A key step of appraisal is to use what
we know about the relationship between different traffic speeds
and traffic flows for different types of roads. We use this to
estimate what the average traffic speed will be if a certain scheme
is implemented. This change in average speed gives us a change
in generalised cost (ie time and money cost), which is used to
estimate the impact on traffic.
25. An investment that speeds up traffic
reduces generalised cost and will tend to increase the number
of people using the road. Our understanding of how to estimate
induced demand has been improving over time. More details on induced
traffic is set out in a report by the Standing Advisory Committee
for Trunk Road Assessment on Transport and the Economy (1999).
26. Carbon emissions are calculated using
levels of traffic and emission factors from the National Atmospheric
Emissions Inventory, which estimates the fuel efficiency of vehicles
at different average speeds.
27. A road investment will generally increase
carbon emissions as induced demand increases total trafficbut
this may be mitigated by a reduction in congestion which means
that traffic may travel at a more fuel efficient speed.
28. The next step of the appraisal is to
work out a monetary value for the carbon dioxide impacts. This
monetised value then feeds into the value for money assessment,
where it is weighed against the other quantified and qualitatively
described appraisal objectives and sub-objectives.
D. How many road projects have been turned
down because of their carbon emissions?
29. Ministers make decisions on individual
schemes taking account of a variety of factors, including:
Value for money (including economic,
social and environmental impacts).
Distributional and equity impacts.
Affordability and financial sustainability.
Contribution to central government,
local and regional objectives.
The amelioration of identified problems.
30. The Value for Money process provides
a single measure of all of the impacts of a schemeeconomic,
social and environmentalbased on an appraisal of the scheme.
This includes the impact of carbon emissions.
31. Decisions on approval of schemes are
based upon the aggregated impacts not on the contribution of individual
elements. Taking account of non-monetised environmental impacts
(eg including carbon emissions, landscape impacts and biodiversity)
in scheme appraisals can have a significant impact on the overall
value for money of schemes, upon which advice to Ministers is
32. As the value for money appraisal takes
account of the environmental impacts and adds them into the decision
making process, they rarely provide the sole basis upon which
schemes are considered. Rather the environmental impacts as quantified
through the value for money process, add further detail to decision
making, which is considered alongside the other factors set out
33. All major road schemes are subject to
a value for money assessment and are put into high/medium/low/poor
value for money categories. Value for money appraisal includes
enviornmental and non-monetised impacts. About 1 in 6 road schemes
have a lower value for money category as a result of environmental
34. We first undertook value for money appraisal
for major schemes in 2004. Analysis of local transport schemes,
costing over £5 million, which were submitted by local authorities
to the Department for funding through the Local Transport Programme,
showed a clear link between value for money and the decisions.
35. Significant adverse environmental impacts
that were key in the decision to reject the funding bids for:
A36 Wylye Valley Relief Road,
B1108 Norfolk hospital road, and
subject to review
A36 Codsford to Heytesbury improvement.
36. These are not the only schemes in this
category. They are the only schemes from the 2004 local transport
E. A breakdown of the figures given in CCP2006
for projected carbon savings from the current VA package, by the
constituent parts of that package, in particular giving savings
figures for the VA alone, and for the increase of "eco-driving"
37. There are a variety of policy measures
in place that provide incentives for manufacturers to produce,
and consumers to purchase, more fuel efficient cars. These include
the EU Voluntary Agreements on new car fuel efficiency, and the
fact that Vehicle Excise Duty and company car tax are both linked
to a vehicle's CO2 emissions.
38. Unfortunately, it is difficult to isolate
the impact of these individual policies on vehicle fuel efficiency
since all are contributing to the same outcome. Apportioning the
resultant carbon savings to individual measures is therefore difficult
to achieve with certainty. As a consequence, the work we carried
out for CCP2006 evaluated these measures as a "package".
Our estimate was that this package of measures would generate
carbon savings of 2.3MtC in 2010. However, as an illustration
of the magnitude of likely carbon savings arising from the company
car tax, HMRC have provided an indicative range of 0.35 to 0.65MtC
saved in 2010.
39. Carbon savings arising from wider transport
measures set out in the 2000 Ten Year Plan and the Future of Transport
White Paper were calculated using DfT's National Transport Model
(NTM). The measures include substantial improvements in local
public transport; various soft measures such as school travel
plans; and development of the sustainable distribution programme
involving both Government and the haulage industry. This latter
policy programme provides drivers and fleet operators with best
practice advice on fuel-saving measures and promotes safer and
more fuel-efficient driving.
40. These wider transport measures are estimated
to save 0.8MtC in 2010. The impact of these measures in Scotland
was evaluated separately and estimated to save 0.1MtC. Analysis
of the impact of individual measures on carbon emissions was not
carried out, due to difficulties in obtaining reliable data and
the synergies between the measures making it difficult to strip
out their individual effects.
F. The basis on which DfT measures the increase
in "eco-driving", and calculates carbon savings resulting
41. The government has a sustainable distribution
programme which is targeted at the road haulage sector and provides
drivers with best practice advice on fuel-saving measures and
promotes safer and more fuel-efficient driving.
42. Analysis based on evidence from case
studies suggests that sustainable distribution policy can deliver
carbon savings. For example, an evaluation of the Safe and Fuel
Efficient Driving scheme (SAFED) for truck drivers found that
drivers achieved an average improvement in miles per gallon of
43. However, further evidence is needed
in order to quantify the full range of potential benefits and
costs. CCP2006 announced additional funding to provide relevant
training and best practice advice for truck and van drivers. This
will help provide further evidence as to the level of carbon savings
that further extensions to the sustainable distribution programme
44. Eco-driving in passenger cars will be
targeted as part of a new communications campaign to promote consumer
information on buying greener vehicles and driving in a more eco-safe
manner. Trials carried out by the Driving Standards Agency suggest
eco-driving could reduce fuel consumption by around 8.5%, though
no estimate of carbon savings has been made.
G. The research findings DfT has on carbon
emissions from high speed rail as opposed both to conventional
rail and short-haul planes
45. Looking at the feasibility and affordability
of a north-south high-speed link (HSL) is a manifesto commitment.
The government has committed to take this forward in the development
of a long term strategy for the railways, drawing on Sir Rod Eddington's
advice on the long-term impact of transport decisions. The rail
strategy will be published in summer 2007.
46. The Department is building on current
understanding of the relationship between train speed and carbon
participating in a train energy measurement
study co-ordinated by the Association of Train Operating Companies
(ATOC) and the Institution of Mechanical Engineers (IMechE). The
study is monitoring in detail the energy consumption of a range
of trains to deliver a more robust understanding of how energy
is used. The outcome should help to inform future train design
as well as giving train operators a clearer understanding of how
they can save energy through, for example, better driver training
or improved maintenance.
leading the project to secure a replacement
to the successful High Speed Trains (Intercity 125s). A key project
objective is to ensure the successor train is as fuel efficient
as possible both to reduce carbon emissions and operating costs.
Therefore, an important element of the appraisal process will
be to model the environmental impact of different train specifications,
including the impact of speed and higher acceleration on carbon
reviewing emerging research such
as the paper by Professor Roger Kemp of Lancaster University to
the IMechE in July 2004
comparing the relative energy consumption of different transport
modes including car, plane and two hypothetical high speed trains
running at 225 and 350 km/h respectively.
H. Why the Government has decided, at least
provisionally, to adopt a multiplier of only 2 on the carbon to
reflect the other contributions of aviation to global warming
in its carbon offsetting, rather than 2.5 (used previously by
HM Treasury), or 2.7 (most commonly used around the world), or
some other figure.
47. Government is proposing the use of a
multiplier as the most appropriate means to include non-CO2
impacts within the offsetting scheme. Note that the adoption of
a simple empirical multiplier for aviation should not infer that
a linear relationship exists between climate forcing and carbon
48. In essence, the use of such a multiplier,
whilst being a well-intentioned attempt to capture the non-CO2
forcing, can only provide an approximation to the impact of non-CO2
impacts. However, the Government believes that a multiplier is
the only feasible and practical way to address non-CO2
impacts within what is a voluntary scheme where there is an emphasis
on minimising the administrative burden from elaborate data collection.
49. The original and previously most widely
supported work relating to the non-CO2 impacts of aviation
is that of the IPCC in 1999, which suggested a reference factor
of 2.7. This factor was used in the calculation methodology to
offset emissions from the 2005 Presidencies of the G8 and EU.
The multiplier of 2.5 was used in a March 2003 joint report by
HMT and DfT on "Aviation and Economic Instruments" to
estimate the climate change related external costs of aviation.
50. More recent research: Trade-Off
updates the estimate of carbon dioxide forcing to the year 2000
and improves the accuracy of the impact assessment, resulting
in a factor of 1.9. This report was not published until July 2005,
too late for incorporation into the G8 and EU Presidency offsetting
calculations which were already committed to the IPCC 2.7.
51. In order to reflect the most recent
and robust scientific evidence currently available, Government
has therefore decided to recognise the more recent TradeOff work
and use a multiplier of 2. The multiplier of 2 has been adopted
for the Government Carbon Offsetting Fund.
52. This decision will be kept under review
as further scientific evidence becomes available. More widely,
the adoption of a multiplier for carbon offsetting should not
be taken to set any precedent or prejudice future decisions over
the best instrument or mechanism for accounting for non-CO2
emissions from air transport within the EU Emissions Trading Scheme.
I. The calculation of carbon savings from
the fuel duty escalator of 1.9MtC in 2010 in CCP 2006how
are these worked out, and what exactly do they mean, given that
it was discontinued in 1999?
53. We compared the impact that the fuel
duty escalator between 1993-99 had on demand to the impact on
demand that revalorisations in fuel duty between 1993-99 would
have had. It was found that due to the fuel duty escalator, demand
for fuel in 2010 will be lower and this lower demand equates to
a carbon saving of around 1.9MtC in 2010.
54. To carry out this analysis we compared
the impact that the fuel duty escalator had on demand to what
would have happened if the escalator had never been introduced.
To do this we needed to compare the impact on demand that the
fuel duty escalator had to the impact the alternative policy would
have had. For this analysis we compared the fuel duty escalator
to revalorisations (increasing rates in line with inflation each
year) in fuel duty.
55. Therefore, in our alternative scenario
instead of fuel duty rising by 3%, 5% and 6% above inflation between
1993-99, we assumed that at every Budget between 1993-99 fuel
duty would only have been increased by inflation. We then estimated
how much higher demand would have been due to the lower pump prices
with this alternative scenario. We then estimated the difference
in demand for fuel between these two policies and therefore the
carbon emissions that the fuel duty escalator had saved.
J. The 20 p/litre duty differential on biofuelsdoes
this depend on what blend of biofuels you fill up with? eg do
you get this for 5% blend, as well as an 85% blend?
56. The 20 pence per litre duty incentive
applies only to the biofuel portion of the mix. For example, for
a 5% biodiesel blend, 5% of the fuel is taxed at 27.1 pence per
litre (ppl) and 95% at 47.1 ppl. For an E85 blend (a mix of 85%
ethanol and 15% normal unleaded petrol), the 85% ethanol is taxed
at 27.1 ppl with the remaining 15% petrol taxed at 47.1 ppl.
2 Available at: http://www.dft.gov.uk/stellent/groups/dft_econappr/documents/pdf/dft_econappr_pdf_610277.pdf Back
Kemp R. J. Environmental impact of high-speed rail. Institution
of Mechanical Engineers. Seminar on High Speed Rail Developments,
21 April 2004. Back
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