www.piarc.org
2022SP03ENCARBON NEUTRALITY OF THE ROADSECTORA PIARC SPECIAL PROJECTCARBON NEUTRALITY OF THE RAOD SECTOR

STATEMENTS
The World Road Association (PIARC) is a non-profit organisation established in 1909 to
improve international co-operation and to foster progress in the field of roads and roadtransport.
This report has been produced by the International Transport Experts Network (ITEN) andResearch Driven Solutions (RDS), under a contract with PIARC, awarded to Maple
Consulting Ltd, an ITEN member. Any views expressed in this report are not necessarily
those of PIARC.
The study that is the subject of this report was defined in the PIARC Strategic Plan 2020–2023 and approved by the Council of the World Road Association, whose members are
representatives of the member national governments. The members of the TechnicalCommittees participating on the Project Oversight Team were appointed by the member
national governments for their special competences.
Any opinions, findings, conclusions and recommendations expressed in this publication arethose of the authors and do not necessarily reflect the views of their parent organisations
or agencies.
This report is available from the internet site of the World Road Association (PIARC):

http://www.piarc.org

Copyright by the World Road Association. All rights reserved.
World Road Association (PIARC)
Arche Sud 5° niveau
92055 La Défense cedex, France
International Standard Book Number: 978-2-84060-727-4
Front cover: Courtesy of Office fédéral des routes OFROU, Switzerland

2022SP03ENCARBON NEUTRALITY OF THE
ROAD SECTORA PIARC SPECIAL PROJECTCARBON NEUTRALITY OF THE RAOD SECTORAUTHORS/ ACKNOWLEDGEMENTS
This report has been prepared by ITEN and RDS as follows:
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Martin LambHelen Viner
Vijay Ramdas
Lorcan Connolly
Emma Sheils

Maple Consulting Ltd / ITEN
Enodamus Ltd / ITEN
Independent Transport Expert / ITEN
Research Driven Solutions
Research Driven Solutions

The authors of this report are grateful for the guidance, support and provision of contacts
provided during the project by the Project Oversight Team (POT), comprising the following
members:
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James Henry (POT Chair)
Gina Ahlstrom
Tsutomu Yoshigi
Anna Wildt-Persson
Laure Gauthiez
Jennifer Slocombe
SouthAustralia, Australia
Luc Vescovi
David Reinhard
Jan Pettersson
Bernard Jacob
Eugenia Correia
Pascal Rossigny
Eric Dimnet(TC 3.4)
Luis Miranda Moreno McGill,
Anna Wildt-Persson
Craig Love
Trevor McIlhatton
Patrick Malléjacq
Miguel Caso Florez

Department for Transport, UK
Federal Highways Administration, USA (TC4.1)
Pasco Corporation, Japan
Trafikverket, Sweden
Federal Office for Roads (FEDRO), Switzerland
Department
for
InfrastructureandTransport,
Ministère des Transport de Québec, Canada-Quebec
Asfinag, Austria
Trafikverket, Sweden (TF 2.2)
Université Gustaf Eiffel, France (TC 2.3), France
Infrastructuras de Portugal, Portugal (TC 4.1)
Cerema, France (TC 3.3 – TF 2.2)
Commissariat Général au Développement Durable, France
Canada-Quebec (TC 2.1)
Trafikverket, Sweden (TC 1.1)
Transport Scotland, UK-Scotland (TC 1.4) to end June 2022
Transport Scotland, UK-Scotland from July 2022
PIARC General Secretariat, France
PIARC General Secretariat, France

2022SP03ENEXECUTIVE SUMMARYCARBON NEUTRALITY OF THE ROAD SECTORA PIARC SPECIAL PROJECTRoad transport is vital for society to function and, for the foreseeable future, is expected
to remain the dominant mode of transport for people and goods. However, theconstruction, operation, maintenance and use of the highway infrastructure areresponsible for large quantities of carbon emissions. Knowledge of the non-reversible,
damaging consequences of climate change has resulted in global acceptance of the needto reduce carbon emissions in all sectors of human activity, including the highways sector.
However, as efficient transport is vital to national economic growth, actions to reducecarbon emissions must not negatively impact the development and maintenance of highquality road infrastructure, particularly for LMICs.
This project aims to identify actions being undertaken as well as potential new options toprogress towards carbon neutrality. Net zero carbon and carbon neutrality represent two
different approaches to combat climate change. There has been a certain amount of
ambiguity in the understanding of what the two approaches represent and there areexamples in literature of the two terms being used interchangeably. However, there is a
general consensus on the definitions for the two approaches, as follows:••

Net Zero carbon: is reducing carbon emissions to as close to zero as possible. Any small
amounts of remaining emissions are then offset by absorption in natural carbon sinks likeforests or using new technologies like carbon capture
Carbon Neutrality: is balancing carbon emissions by ‘offsetting’, i.e., separately removing
carbon in the atmosphere to balance that which is emitted

The above definitions have been adopted by PIARC and form the basis of their use
throughout this report.
In practice, many highway authorities making progress on decarbonisation are adopting a
combination of these approaches, having established target dates for achieving Net Zero
carbon (generally aligning with the policies set by national governments) and also, in the
short term where it is not yet possible to decarbonise, purchasing carbon offsets to mitigate
the impact of emissions. This approach has been followed for some major construction
schemes with potential for high emissions.
Part A of this report examines the policies and strategies being adopted by National Road
Administrations (NRAs). 83% of questionnaire respondents reported that their country had
Net Zero targets in place. Irrespective of whether targets are in place, a range of strategies
are being adopted for reducing carbon emissions. The report summarises the major
themes, which appear to have a high degree of commonality across the world and are being
adopted in both LMICs and HICs. Three case studies are highlighted: the Net Zero strategy
adopted by National Highways in the UK, which has the most well-developed policy
identified, and two road improvement projects where a range of actions were taken to
reduce emissions. The levers available to road authorities through their procurement

EXECUTIVE SUMMARY
practices and relevant practice from the rail sector are reviewed. Finally, the need toachieve a ‘fair transition’ is discussed, in which carbon emissions are reduced without
impeding economic growth in developing countries and regions.
Part B of this report examines the technical solutions that are available for decarbonisation
and, for specific technologies, the potential carbon savings were estimated. The
technologies considered are summarised below.

EXECUTIVE SUMMARY
Technical solutions
Construction and maintenance of road infrastructure
A hierarchy of options exists, beginning with challenging
the need for new construction, plus effective
maintenance of existing assets. Further opportunities
exist through planning works to reduce emissions,adopting low carbon materials and decarbonising
construction plant. Roads can also be designed toreduce rolling resistance for road users.
Decarbonisation of road user vehicles
Road user carbon is the largest component of roademissions. Options will depend on national policy andcan be supported by NRAs. Biofuel is already in use andelectrification appears a promising option for cars andlight vans. For heavy vehicles various options underdevelopment include battery electric, electric roadsystems and hydrogen.
Operations on the road network
Lighting (including road signs and signals) provides a
critical role in road safety and forms a high proportion of
corporate emissions for many NRAs. Lighting energy canbe reduced considerably by LEDs. NRAs also have arole to reduce the impact of their sizeable vehicle fleetsand find solutions for specialised use cases such as
recovery vehicles, gritters and snow ploughs.
Road user choices
Well-designed networks for non-motorised travel cangive road users a healthy alternative to short car
journeys. Likewise, passenger-centred public transport
can provide an alternative to low-occupancy private
vehicle use. Various incentives and penalty schemes
have been adopted to encourage modal shift.

EXECUTIVE SUMMARY
Carbon offsetting
There are various approaches to removing atmosphericcarbon or avoiding its release. The scale of road carbon
emissions is too large to be substantially balanced bythese methods, although they offer a means of mitigating
emissions that are currently unavoidable. There areseveral certified schemes but there are also concerns
whether the claimed benefits are realised.

In Part C, a more in-depth investigation was carried out into specific solutions in two areas,
namely, lighting and road construction/maintenance. For this, additional interviews were
undertaken to supplement the literature reviews and findings of the questionnaire.
For the review on LED lighting, current guidelines and targets were explored, followed byvarious examples of cities or road networks who had rolled out LED lighting schemes, andsuccess factors. Finally, a review of factors that road administrations should consider ifplanning an LED scheme is presented. Whilst LED lighting is a mature technology, which has
been successfully deployed worldwide, the key factors to be considered are as follows:
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Technology: Current system in place, lighting intensity required, smart systems anddimmability
Economic: Finance, payback and maintenance
Location: Standalone systems or solar/ wind powered systems
Environmental: Carbon savings, recyclability and biological impacts
Other: Political factors and skillset

The second area of more detailed investigation was around the much broader category ofroad construction and maintenance. Here, the review considered the importance ofbaseline levels and strategies to drive carbon reduction and consideration of how
construction can be designed to be more resource efficient based on local conditions. Casestudies and findings on the use of low carbon concrete and reclaimed and recycled asphalt
are presented, as the main constituents of highways, along with other secondary materials,
such as recycled tyre, steel slag waste and coal combustion by-products. The key
conclusions in the area are as follows:•••

Existing carbon emissions need to be baselined the major sources of emissions identified
so that an appropriate reduction strategy can be developed
Scenarios evaluated should take account of local conditions (e.g., transport distances andthe efficiency of local plant) and all phases of the lifecycle should be evaluated. The systemboundaries should also be studied carefully, in case an apparent reduction in emissions in
one area results in displacing the burden to a different part of the process
Existing design strategies can be challenged to allow for greater resource efficiency

EXECUTIVE SUMMARY••

Early engagement with industry stakeholders in the project development stage can allow
ways to reduce carbon to be investigated, and drive motivation for further innovation
Suppliers should be required to produce information on the carbon (and other) impacts of
their products to drive a focus on reduction

Estimates of carbon savings for the technologies identified in section B are presented.
These estimates are extrapolated from the data available, however they indicate there issignificant potential to reduce carbon at all stages of the highway lifecycle. Specific areas
identified are as follows:
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Review the need for road construction to allow other options, such as active travel andpublic transport to be considered
A well maintained and smooth pavement will lead to lower emissions from vehicles using
it. With various assumptions made on worldwide road length and maintenance intervals,
potential savings of between 25-28 million tonnes of CO2 annually could be achieved bychoosing maintenance practices such as chip seal and crack seal over thin overlays
Low carbon construction can offer carbon savings across three main areas of carriageway
construction; materials reduction and reuse, energy reduction and transportation
efficiencies
Low carbon concrete: the production of cement is very carbon intensive. Carbon reduction
can be achieved using biothermal and renewable energy to produce cement and by
reducing clinker or using clinker substitutes. Subject to development and implementation,
an ongoing increased reduction of about 7.5 million tonnes of CO2 could be achieved
annually by 2030, based on an assumption that 10% of cement is used in the road
construction sector
Construction of smooth and stiff pavements can reduce transport emissions, by improving
fuel efficiency of the vehicles driving on them. When compared to conventional pavement
construction, the CO2 savings associated with low rolling resistance pavements could be
between 6,000 and 12,000 tonnes, per 1 km of high traffic, 4-lane carriageway during a 15year life
The use of circular economy approaches has the potential to make a significant contribution
to completing the decarbonisation of the transport sector, although the savings are
currently site specific, as these approaches remain in trial stages generally
Low carbon materials are available that offer significant carbon savings over conventional
materials, for example, the use of warm mix or cold mix asphalt in place of hot mix asphalt
could save around 8 to 16 tonnes per 1 km of 4 lane carriageway
Many smaller items of construction plant, such as mini diggers, are now offered in battery
electric variants, whilst trials are underway of direct burn of hydrogen trialled and hydrogenfuel cell operation for large plant. Road maintenance activities alone may emit 8 million
tonnes of CO2 per year. There is the potential to save a significant proportion (potentially
up to 50% for some sites and operations) through job site optimisation, machine
optimisation and machine control. There is the potential for the remainder to be poweredby electricity or hydrogen
The use of solar powered lighting solutions for construction sites is increasingly replacing
diesel generators. Some claim to be able to operate year-round, even when there are 16
hours of darkness, whilst others are solar hybrid with a diesel back up. It could be possible
to save 5 tonnes of CO2 per year, per unit by switching to either solar power, or greenhydrogen. Estimating the potential savings achievable by replacing diesel generators with

EXECUTIVE SUMMARY
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solar power or green hydrogen is far more difficult due to the large variations in the size
and applications, however, savings could be in the order of millions of tonnes per year
Emissions generated from vehicles using the road represent the largest source of carbon at
5.6 billion tonnes, but the one with which national road administrations have the least
control. Theoretically, all this could be provided by carbon neutral means, through electricvehicles being charged with electricity produced by renewables, or green hydrogenproduced by electrolysis of water, powered by renewable energy. Better use of existingroads through higher vehicle occupancy, public transport or infrastructure designed forwalking and cycling could decrease carbon emissions in the short to medium term
LED lighting as a replacement for traditional lights can offer savings. In some countries solar
lighting solutions can reduce electricity consumption from the grid to zero. Whilst the
carbon savings from switching to LED lighting depends greatly on type of system being
replaced, globally, the world has approximately 363 million streetlights. It is estimated thatby replacing an additional 10% with LED technology, global annual reductions of between
2.5 – 16.5 million tonnes of CO2 could be achieved
As with highways, the rail sector also has targets for decarbonisation and there is goodpractice that can be shared, including examples of measuring and managing carbon,
production of renewable energy on estates, certification of electricity being of green origin
and power purchase agreements to fund for zero carbon power solutions
Non-Motorised Transport (NMT) can offer significant carbon savings and offer economic,
social and health benefits. However, it is crucial that the schemes are designed with NMT
as a priority from inception rather than an add on to motorised schemes. In England, it isexpected that there will be between 1-6 million tonnes of CO2 reduction between 2022 and2030 due to a reduction in car emissions by promoting public transport, cycling or walking
as the natural first choice for those capable. If these figures for England were extrapolated
globally, an estimated additional reduction between 2-13 million tonnes of CO2 could
potentially be achieved annually
Transfer to public transport offers the potential for carbon savings, whilst making betteruse of the existing infrastructure. Figures from the UK indicate that a modal shift fromprivate car to bus transport for 10% of the public would result in a reduction in the rangeof 5.8 million tonnes of CO2 annually. Extrapolation of the figures to a global scale would
lead to a reduction of potentially up to 190 million tonnes of CO2 annuallyPart D of the report presents our conclusions and recommendations. Whilst there is thepotential to reduce carbon across various areas of road construction, maintenance andoperation, the extent to which road administrations have control over the sources ofemissions differs. For example, choosing to install LED lighting or purchase green electricity
is entirely within the remit of road administrations. Whilst not in their direct control, roadowners can request and facilitate the use of lower carbon materials on their network.
Finally, for decarbonisation of the vehicles using the network, the road owners have theleast influence, but can support wider governmental targets by providing, e.g. EV charging
stations. A table of technology options, potential carbon savings, road owner control andsuitability for LMIC or HIC is presented.
Much progress has been made, in LMICs and HICs, on establishing policies and pledges todecarbonise road transport, with large numbers of examples demonstrating progress in
reducing carbon emissions by NRAs. However, it is also clear that long-term strategies forEXECUTIVE SUMMARY
delivering the transformation needed to become carbon-neutral or reach net-zero acrossall their networks are either in the early stages of development or yet to start. During thisresearch the following themes have emerged as important enablers:
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Strategy - it is necessary to develop a long-term-strategy, setting out a roadmap withintermediate target dates for reducing carbon emissions. With published target dates fornet-zero for most countries within a 30-year horizon, this process must begin urgently.
Establishing a baseline of the sources of current emissions is an essential early step toidentify the areas for focus and to measure progress in achieving reductions
The knowledge, skills, mindsets and behaviours of the entire workforce (e.g. policy makers,
delivery teams, supply chain), all play a significant role in achieving decarbonisation as they
are collectively responsible for identifying and evaluating options, managing procurementand delivering the solutions identified. Road administrations should invest in the skills andknowledge of their personnel and ensure that their supply chains do likewiseSome initiatives for decarbonisation will be outside the influence of individual NRAs, e.g.
incentivising uptake of EVs. NRAs should adopt a proactive role in engaging with otheragencies and leading cooperation throughout the supply chain to facilitate change
The approach adopted by NRAs in procurement greatly influences the response of the
supply chain. To achieve decarbonisation, standards (e.g. construction, maintenance,materials, safety etc), must actively encourage innovation and enable the development andadoption of new materials, ways of working etc that have lower carbon impacts. Road
administrations should review their standards and tender evaluation criteria so thatappropriate weight is given to decarbonisation
For road construction and maintenance, whole life analysis (WLA) of carbon impacts is
critical to understanding the most carbon efficient solution for specific situations. Road
administrations should develop the assessment of carbon impacts within WLA and makethis a routine part of options appraisal
A striking finding from the gap analysis is the limited rigour of the evidence presented on
the actual or potential reductions in carbon emissions due to adopting particular strategies
when implementing projects. This makes it difficult for road administrations to learn fromthe experience of others and assess how best to pursue their own goals of carbon
neutrality. Road administrations should support evidence gathering, data collection,
identifying success factors and sharing knowledge of lessons learned

Finally, road administrations have significant opportunity to play an important role in
reducing carbon emissions, whilst maintaining mobility for road users. Many of thesolutions identified in this report can assist them in doing so.

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CONTENTS1INTRODUCTION ............................................................................. 6

1.1

TRANSPORT CONTRIBUTION TO GLOBAL CARBON EMISSIONS ................................ 6

1.2

CLASSIFICATION OF SOURCES OF EMISSIONS ......................................................... 9

1.3

SOURCES OF ROAD TRANSPORT EMISSIONS ....................................................... 11

1.4

STRUCTURE OF THIS DOCUMENT ......................................................................... 12

PART A – POLICIES, STRATEGIES AND PROCUREMENT .............. 14
2

POLICIES AND STRATEGIES ...................................................... 14

2.1

NATIONAL TARGETS FOR DECARBONISATION ....................................................... 14

2.2

NRA STRATEGIES TO ACHIEVE NET ZERO/CARBON NEUTRALITY ........................... 15

2.3

QUESTIONNAIRE FINDINGS ................................................................................. 20

2.4

CASE STUDIES .................................................................................................. 23

2.5

PROCUREMENT OF LOW CARBON OPTIONS.......................................................... 25

2.6

LESSONS FROM RAIL SECTOR............................................................................. 34

2.7

POTENTIAL IMPACTS OF POLICIES AND STRATEGIES ON SOCIAL INEQUALITIES ........ 38

PART B – TECHNICAL SOLUTIONS .................................................. 41
3 CONSTRUCTION AND MAINTENANCE OF ROADINFRASTRUCTURE ............................................................................. 41
3.1

NEED FOR ROAD CONSTRUCTION ........................................................................ 41

3.2

ROAD MAINTENANCE AND LIFE EXTENSION .......................................................... 42

3.3

LOW CARBON CONSTRUCTION ............................................................................ 44

3.4

CIRCULAR ECONOMY AND RESOURCE EFFICIENCY ................................................ 48

3.5

LOW CARBON MATERIALS .................................................................................. 50

3.6

LOW ROLLING RESISTANCE PAVEMENTS .............................................................. 55

3.7

DECARBONISATION OF CONSTRUCTION PLANT AND CONSTRUCTION OPERATIONS ... 57

4

DECARBONISATION OF ROAD USER VEHICLES ..................... 69

4.1

ALTERNATIVE FUELS / BIOFUELS ........................................................................ 69

4.2

CARS AND VANS ............................................................................................... 71

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4.3

BUSES ............................................................................................................. 74

4.4

HEAVY GOODS VEHICLES .................................................................................. 76

5

OPERATIONS ON THE ROAD NETWORK .................................. 81

5.1

VEHICLES OPERATED BY ROAD ADMINISTRATIONS ............................................... 81

5.2

LED LIGHTING .................................................................................................. 81

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ROAD USER CHOICES ................................................................ 85

6.1

TRANSFER TO ACTIVE TRANSPORT ..................................................................... 85

6.2

TRANSFER TO PUBLIC TRANSPORT ..................................................................... 88

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CARBON OFFSETTING................................................................ 93

7.1

METHODS TO REMOVE CARBON .......................................................................... 93

7.2

OFFSETTING SCHEMES ...................................................................................... 95

7.3

LIMITATIONS OF OFFSETTING SCHEMES ............................................................... 95

PART C – CASE STUDIES .................................................................. 98
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LED LIGHTING.............................................................................. 98

8.1

CURRENT GUIDELINES AND TARGETS ................................................................. 98

8.2

BUSINESS CASE – CASE STUDIES ....................................................................... 99

8.3

CONSIDERATIONS FOR ROADS AUTHORITIES ...................................................... 108

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ROAD CONSTRUCTION............................................................. 111

9.1

BASELINE LEVELS AND ONGOING STRATEGIES FOR CARBON REDUCTION ............. 111

9.2

OPTIMISED DESIGN .......................................................................................... 113

9.3

USE OF LOW CARBON CONCRETE ..................................................................... 114

9.4

USE OF RECLAIMED ASPHALT ........................................................................... 118

9.5

CASE STUDIES ON RECYCLED ASPHALT ............................................................. 119

9.6

USE OF OTHER SECONDARY MATERIALS IN ROAD CONSTRUCTION ....................... 124

9.7

CONSIDERATIONS FOR ROADS AUTHORITIES ...................................................... 126

PART D – CONCLUSIONS AND RECOMMENDATIONS .................. 127
10 GAP ANALYSIS .......................................................................... 127

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11 SUMMARY OF TECHNICAL SOLUTIONS AND POTENTIAL
CARBON SAVINGS ........................................................................... 132
11.1 CONSTRUCTION AND MAINTENANCE OF ROAD INFRASTRUCTURE ........................ 132
11.2 DECARBONISATION OF ROAD USER VEHICLES .................................................. 135
11.3 OPERATIONS ON THE ROAD NETWORK ............................................................. 136
11.4 ROAD USER CHOICES ..................................................................................... 137

12 RECOMMENDATIONS................................................................ 143
13 GLOSSARY................................................................................. 147
14 ACKNOWLEDGEMENTS............................................................ 149
14.1 QUESTIONNAIRE ............................................................................................. 149
14.2 FOLLOW-ON DISCUSSIONS .............................................................................. 151

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FIGURES
Figure 1. CO2 emissions from fuel combustion by sector ....................................................................... 7
Figure 2. Global transport emissions by subsector 2000 – 2030 ............................................................ 9
Figure 3. Key Emissions ......................................................................................................................... 10
Figure 4. Relative energy use per activity ............................................................................................. 12
Figure 5. Document structure ............................................................................................................... 12
Figure 6. Geographical spread of the questionnaire responses received ............................................. 21
Figure 7. Responses indicating presence of net zero or carbon neutrality policies.............................. 22
Figure 8. Strategies being adopted for reducing carbon emissions ...................................................... 22
Figure 9. The sustainable transport hierarchy87 .................................................................................... 42
Figure 10. A comparison of CO2 emissions from the construction sector in Sweden ........................... 47
Figure 11. Distribution of emissions in the Swedish infrastructure sector ........................................... 47
Figure 12. Effect of potential rehabilitation strategies on CO2 emissions ............................................ 55
Figure 13. Contact pressures between the tyre and pavement surfaces ............................................. 56
Figure 14. Sources of electricity production by country ....................................................................... 68
Figure 15. Hydrogen filling station at National Renewable Energy Laboratory, Colorado ................... 74
Figure 16. eHighway in Sweden ............................................................................................................ 77
Figure 17. E39 Coastal Route Map ........................................................................................................ 78
Figure 18. E39 CO2 emissions when applying different possible reduction strategies ......................... 79
Figure 19. Household CO2 savings from using public transport instead of private car ......................... 89
Figure 20. Reduction in sale price of retrofit LED lamps and CFLs replacement for a 60W incandescentlamp ..................................................................................................................................... 100
Figure 21. Business Case for Hamilton LED conversion ...................................................................... 104
Figure 22. Evaluation of Solar/wind powered streetlights in Western Australia................................ 106
Figure 23. National Highways – sources of carbon emissions from construction and maintenance in2020 ..................................................................................................................................... 111
Figure 24. Structural condition achieved for case study project ........................................................ 113
Figure 25. Lifecycle CO2e per 1 km, by road type and component ..................................................... 117
Figure 26. Number of States with Estimated RAP% in the ranges shown .......................................... 118
Figure 27. Relative lifecycle cost for HMA with 40% RA, compared with virgin material................... 123
Figure 28. Summary of the strategies reviewed ................................................................................. 128
Figure 29. Extent to which the strategies reviewed have been adopted ........................................... 129

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TABLES
Table 1. Net Zero Tracker – Global (2022) ............................................................................................ 15
Table 2. Countries surveyed under EY Green Tax Tracker .................................................................... 29
Table 3. Lifecycle cost considerations for cold mix asphalt deployed in Assam ................................... 51
Table 4. Typical diesel use from construction plant .............................................................................. 58
Table 5. Estimate of worldwide, annual carbon emissions associated with use of plant ..................... 59
Table 6. Lighting technologies comparative table................................................................................. 84
Table 7. Estimate of the benefits of public transport in reducing CO2 emissions in USA in 2005 ........ 89
Table 8. Lighting costs in 2 pilot schemes in San Sebastian ................................................................ 103
Table 9. Outline of considerations for planning lighting schemes ...................................................... 108
Table 10. Estimated ranges for C32/40 concrete ................................................................................ 115
Table 11. Lifecycle GHG emissions per km of new concrete pavement ............................................. 116
Table 12. LCA predictions using conventional and recycled materials ............................................... 120
Table 13. Lifecycle costs for pavement designs using conventional and recycled materials ............. 122
Table 14. Summary of the use of additional recycled materials, reported to NAPA for 2020 ........... 124
Table 15. Summary of the potential for carbon reduction from use of recycled materials ............... 125
Table 16. Number of examples by region ........................................................................................... 131
Table 17. Number of examples by country type ................................................................................. 131
Table 18. Summary of solutions in achieving carbon savings ............................................................. 139

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1 INTRODUCTION
Road transport is vital for society to function, enabling work, leisure and other essential travelfor people, and the transport of goods between source and destination. Roads will continue
to be the dominant mode of transport for people and goods in the foreseeable future. At thesame time, the construction, operation, maintenance and use of the highway infrastructure
are responsible for large quantities of carbon emissions. Of these emissions, the largest
proportion result from vehicles using the infrastructure.
Knowledge of the non-reversible, damaging consequences of climate change has resulted in
global acceptance of the need to reduce carbon emissions in all sectors of human activity,
including the highways sector. However, as efficient transport is vital to national economic
growth, actions to reduce carbon emissions from the sector must not negatively impact thedevelopment and maintenance of high-quality road infrastructure, particularly for LMICs (Lowand Middle Income Countries).
This project funded by PIARC aims to identify actions being undertaken by the sector as wellas potential new options to progress towards carbon neutrality. Net zero carbon and carbon
neutrality represent two different approaches to combat climate change. There has been acertain amount of ambiguity in the understanding of these two approaches and there areexamples in literature of the terms being used interchangeably1. However, there is a generalconsensus on the definitions for the two approaches, as follows:••

Net Zero carbon: is reducing carbon emissions to as close to zero as possible. Any small
amounts of remaining emissions are then offset by absorption in natural carbon sinks likeforests or using new technologies like carbon capture
Carbon Neutrality: is balancing carbon emissions by ‘offsetting’, i.e., separately removing
carbon in the atmosphere to balance that which is emitted

The above definitions have been adopted by PIARC and form the basis of their use throughout
this report. Whilst the stated aim of the project is to identify best practice andrecommendations to support PIARC members achieve carbon neutrality, on a global scale thiswill only be achievable in the necessary timeframe with a significant reduction in carbon
emissions. This report therefore presents an overview of current and potential future practiceand technologies that could help the roads sector to contribute significantly to a low or zerocarbon transport future.
1.

TRANSPORT CONTRIBUTION TO GLOBAL CARBON EMISSIONS

Total global CO2 emissions increased between 2010 to 2019 and following a temporary
reduction on 2020 due to the Covid-19 pandemic, rebounded in 2021 to reach a total of 36.3Gt

1 https://webflow.plana.earth/academy/what-is-difference-between-carbon-neutral-net-zero-climate-positive#:~:text=When%20carbon%2Dneutral%20refers%20to,energy%20as%20%E2%80%9Czero%20carbon.%E2%80%9D

CARBON NEUTRALITY OF THE ROAD SECTOR

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2 (36.3 billion metric tonnes). The transport sector share of the total emissions ranges between

20 to 25% 3 and within the transport sector, the roads sector accounts for around 71% of fuelcombustion as outlined in Figure 14, below. Note that the chart shows the figure for CO2 fromfuel combustion. When using this measure, transport’s share of CO2 emissions is 31%; rather
than the 20 – 25% share of overall emissions listed above. This reflects the fact that most of
the CO2 emissions from transport (apart from some electrically powered rail) comes from fuelburnt for propulsion, whereas in other sectors there might be a higher proportion of CO2
emissions resulting from other sources, such as materials extraction.

Figure 1. CO2 emissions from fuel combustion by sector(Source: IEA/UIC (2012) Energy consumption and CO2 Emissions of World Railway Sector. All rights reserved)4Specific worldwide examples of this are as follows:••

China5: in 2020 the total emissions, at 11,680 MtCO2e (11,680 million metric tonnes), was thehighest in the world with the transport sector accounting for around 70%. China is also one of
the leading spenders on transitioning to clean energy and has announced a focus on “fossil
fuel ban” as the main driving force to achieve net-zero emissions by 2050
USA6: In 2020, the transport sector contributed 27% of the total emissions of 5,981 MtCO2e.
As with the EU and UK, the transport sector has the largest share of the total emissions,primarily from fossil fuels used by motorised vehicles

2 Global Energy Review: CO2 Emissions in 2021 – Analysis - IEA
3 Cars, planes, trains: where do CO2 emissions from transport come from? - Our World in Data
4 International Energy Agency and the International Union of Railways, Energy consumption and CO2 Emissions of World Railway Sector,

2012, iea-uic_2012final-lr.pdf.
5 Toward Net Zero Emissions in the Road Transport Sector in China | WRI China
6 Sources of Greenhouse Gas Emissions | US EPACARBON NEUTRALITY OF THE ROAD SECTOR

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•

•

•

•

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EU7: The EU’s greenhouse gas emissions totalled approximately 4,375 MtCO2 e in 20178, withtransport responsible for a quarter. In contrast to other sectors, GHG emissions from thetransport sector have continued to increase in the last 3 decades. Road transport, in generalaccounts for the largest share and in 2019 accounted for 71.7% of the EU-27 transport sector
emissions. Looking ahead, transport sector emissions are predicted to decrease, and the road
sector is expected to contribute the largest share of the reduction (most of it coming fromreduction in emissions from passenger cars)
UK8: In 2019, the transport sector was responsible for 27% of total emissions of 455 MtCO2e.
Within the transport sector, cars and taxis were responsible for 61% (68 MtCO2e) of theemissions, Heavy Goods Vehicles 18% (19.5 MtCO2 e) and vans 17% (19 MtCO2e)
India9: In 2020, emissions from the transport sector were reported to be 277 MtCO2e.
Transport is the 3rd most CO2 emitting sector and, as with other countries, the roads sector
bears the largest share (90%). As a developing country with a growing economy, India is in theearly stages of building its highway infrastructure and has a rapidly expanding car ownershipprofile. But the country has declared a Net Zero target to be achieved by 2070 and the highway
sector is committed to the target
Canada10: transport is Canada’s second highest carbon emitting sector, contributing 186 Mt
CO2 e per year (25% of all emissions), behind the oil and gas industry which emits 191 Mt CO2.
In such a large and diverse country, there are significant differences between the provinces;for example, the transportation sector accounted for approximately 12% of Alberta’s11 annual
GHG emissions, which is the third largest sector after oil/gas and electricity
Australia: transport in Australia in 202112 represents 17.5% of emissions, however, there are
significant differences between the States. For example, in South Australia, transport’s GHG
emissions share was 25%13 due to the decarbonised grid in the State compared to Australia asa whole, lowering the relative shares of emissions of other sectors. As such, there is great
potential for EVs to lower overall emissions in the state

It is notable that the LMIC examples above show transport as having a much higher share of
total emissions, 70% and above, compared to HIC (high income countries) share being around20-25%. This is presumably due to HICs having higher overall emissions from, for example,
higher residential energy use through electricals and white goods, such as fridges and washingmachines.
Whilst there was a fall in global CO2 emissions in 2020 due to reduced industrial activity andrestrictions on mobility caused by the COVID pandemic14, energy related emissions grew to36.3 GtCO2, in 2021, a record high15. Oil use for transport in 2021 remained below pre-7 Transport and environment report 2021 Decarbonising road transport — the role of vehicles, fuels and transport demand.

https://www.eea.europa.eu/publications/transport-and-environment-report-2021
8https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/984685/transport-and-environmentstatistics-2021.pdf
9 CAT_2020-12-09_Report_DecarbonisingIndianTransportSector_Dec2020.pdf (climateactiontracker.org)
10 https://www.canada.ca/content/dam/eccc/documents/pdf/cesindicators/ghg-emissions/2021/greenhouse-gas-emissions-en.pdf
11 Climate change and transportation, Government of Alberta, Canada, Climate change and transportation | Alberta.ca
12 https://www.dcceew.gov.au/climate-change/publications/national-greenhouse-gas-inventory-quarterly-update-march-2021
13 https://www.environment.sa.gov.au/topics/climate-change/south-australias-greenhouse-gas-emissions
14 https://www.iea.org/reports/global-energy-review-2021/co2-emissions#abstract
15 https://www.iea.org/reports/global-energy-review-co2-emissions-in-2021-2

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pandemic levels, with demand reduced by 6 million barrels per day below 2019 levels andemissions 600Mt lower.
Even with the reduction in demand in 2020, global CO2 emissions in 2020 from transport
amounted to over 7 Gt, of which road transport emissions (two and three wheelers, light duty
vehicles, bus and minibus and heavy trucks) accounted for 5.6 Gt16, as shown in Figure 2.,
below. To reach the Net Zero Emissions by 2050 Scenario, requires a 20% reduction in totaltransport emissions to 5.6 Gt by 2030.

Figure 2. Global transport emissions by subsector 2000 – 2030 (reproduced from IEA)

In reporting national GHG inventories, the ‘transport sector’ includes vehicle emissions only,
which are the largest but, by no means, the only source of emission in the road transport
sector. Emissions surrounding e.g. concrete for road construction, or steel for lighting columns
would be recorded elsewhere and these need to be considered by transport agencies whenplanning the path to zero emissions. More information is provided in Figure 4.
2.

CLASSIFICATION OF SOURCES OF EMISSIONS

16 IEA (2021), Tracking Transport 2021, IEA, Paris https://www.iea.org/reports/tracking-transport-2021

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There are three classifications defined within the Greenhouse Gas Protocol (GHG Protocol)17
that are used internationally to describe and understand sources of emissions18. As applied to
NRAs, they represent:
Scope 1 – This covers emissions from sources directly controlled by the NRA and are the direct
result of their activities, for example, the fuel used in their fleet vehicles (non-EVs).
Scope 2 – This covers indirect emissions associated with the activities of the NRA based onemissions from purchased energy, e.g. the electricity purchased by the NRA and used to power
EVs. The emissions physically occur at the location where the energy is produced.
Scope 3 – Indirect emissions associated with the NRA and not covered within Scope 2. These
are indirect emissions associated with activities up and down the NRA’s supply chain, i.e. theemissions are linked to NRA operations but not controlled directly. For example, the use ofgoods purchased from a supplier or from the company’s own products when customers use
them.
Scope 1 and Scope 2 emissions are mostly within the control of the NRA. Emissions from Scope
3 are the more difficult to quantify and are also the most difficult to reduce19. Figure 320
illustrates the key emissions as outlined in the Greenhouse Gas Protocol standards.

Figure 3. Key Emissions(Reproduced from National Highways Net Zero Highways plan)

While the GHG Protocol identifies, explains, and provides options for GHG inventory bestpractices, ISO 14064 “International Standard for GHG Emissions Inventories and Verification”

17 FAQ.pdf (ghgprotocol.org)
18 What are scope 1, 2 and 3 carbon emissions? | National Grid Group19 What are scope 1, 2 and 3 emissions? | Deloitte UK
20

net-zero-highways-our-2030-2040-2050-plan.pdf (nationalhighways.co.uk)

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is an international standard that acts as a guide to the public and private sector in quantifying
and reporting GHG emissions21. ISO 14064 is climate policy neutral but can be used as a basis
to develop GHG inventories and develop policies in relation to climate change.
National Highways in the UK has taken the approach to identify and categorise sources ofemissions within the road network and has set specific targets within each category to reach
Net Zero between 2030 and 2050. The distinction between groups is different to theGreenhouse Gas Protocol definition and forms a logical approach against which detailed plans
can be developed for reduction. The following three categories are identified22:
Corporate Emissions – This covers energy used and travel by National Highways. For example,
this includes energy purchased and fuel used by fleet vehicles
Maintenance & Construction Emissions – This includes all emissions associated with the
production and transport of materials required to construct and maintain roads within the
network
Road User Emissions – These cover emissions from users of the road network
3.

SOURCES OF ROAD TRANSPORT EMISSIONS

While the largest source of emissions are the vehicles using the road networks, as shown in
Figure 4, the construction (e.g. new build), operations (e.g. street lighting, tunnel lighting andventilation) and maintenance of the highway network also represent large sources of carbon
emissions.

21 ISO 14064 International Standard for GHG Emissions Inventories and Verification (epa.gov)
22 https://nationalhighways.co.uk/netzerohighways/

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Figure 4. Relative energy use per activity

Whilst the 4 circles in Figure 4, covering lighting, maintenance and construction are dwarfed
by the magnitude of vehicle energy use, they are not insignificant either proportionately or interms of total CO2 emissions. In addition, these are the areas where road administrations havea greater ability to take actions to reduce emissions, acting independently or working incollaboration with its supply chain. Road administrations do have some influence on vehicle
energy use by, for example, having well maintained and free flowing roads that promotevehicle fuel efficiency, supporting transition to low emission driving, such as providing
efficient infrastructure for electric vehicles (EV), enabling a more friendly infrastructure forpublic transport vehicles, non-motorised vehicles, pedestrians etc.
4.

STRUCTURE OF THIS DOCUMENT

This document details practices and technologies to reduce carbon emissions and achievecarbon neutrality in the highways sector. It is divided into three sections plus conclusions andrecommendations, as shown in Figure 5 below.
Part A contains a review of existing policies and strategies adopted by state and national
Governments and road administrations, highlighting good practice and opportunities for the
future.
In Part B, the technical solutions and opportunities for the future are explored.
Part C, takes a deeper dive into two specific solutions, namely, LED lighting and road
construction.
Part D of the report presents our conclusions and recommendations.

Policies andStrategies

Technical
solutions

Case studies

Conclusions
andRecommendations•What Government
and NRAs say they
will do•How they can do it•What the options
are and evidence
they work•Deep dive on how
this works inpractice•What approach to
takePART APART BPART C

Figure 5. Document structure

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Much of the literature reviewed pertains to national highway networks or road networks
operated by National Road Authorities (NRAs). Local and regional roads operated by local
authorities are not addressed specifically, despite many countries having extensive local road
networks, that may carry significant freight traffic contributing to a relatively significant
proportion of carbon emissions. It is also acknowledged that in many LMICs, the road network
is operated in a fashion more similar to management of local and regional road networks in
HICs. This should be given due consideration when reviewing the data contained within thisreport and in particular, the recommendations. However, many of the approaches andrecommendations drawn are applicable to all networks, and governments must always
consider the full picture of road transport emissions within any strategy for net-zero andcarbon neutrality, and utilise measures which are shown to be effective for the type of road
network being addressed.

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PART A – Policies, Strategies and Procurement
2 POLICIES AND STRATEGIESThe need to address the consequences of steadily intensifying climate change has gained
momentum globally in the last decade and national governments have responded by making
strong commitments to reduce their GHG emissions.
2.1

NATIONAL TARGETS FOR DECARBONISATIONOn global as well as national scales, significant reduction in carbon emissions is key tomitigating climate change impacts. Over the last few years, globally there has been increasing
momentum towards achieving Net Zero23. A significant number of national governments havetherefore defined their policies based on setting or starting the process for setting thedirection to achieve Net Zero.
Table 1 shows the 2022 position with respect to stated Net-Zero policy for 130 countries. Two
countries, Bhutan and Suriname have already achieved ‘carbon negative’ status and theirchallenge is to maintain this status in the face of expanding road infrastructure and growing
numbers of vehicles (currently mainly fossil fuel based). The other 128 countries (78 LMICs
and 50 HICs) have set or are in the process of setting target dates spanning the period 2030
to 2070. It is interesting to note that, since 2019 when the UK became the first major economy
to enshrine ‘Net Zero by 2050’ in law, to date only 15 HICs (which includes the EU bloc) and
one LMIC have followed suit.
The stated aim of the project is to identify options for carbon neutral roads. While countries
do not appear to have adopted carbon neutrality as a target, there is recognition that
achieving net-zero nationally will not mean that every sector or area of the country will alsoreach absolute zero emissions by the same date. The reality is that some sectors or aspects
within a sector could still be ‘net sources’ of GHG by the planned target date and in that case,the emissions would need to be offset by other sectors or aspects of sectors that are ‘net
sinks’. So, in effect, strategies to achieve net zero include development of options to absorb
emissions from the atmosphere, i.e. offsetting.

23 https://www.un.org/en/climatechange/net-zero-coalitionCARBON NEUTRALITY OF THE ROAD SECTOR

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Table 1. Net Zero Tracker – Global (2022)

2.2

NRA STRATEGIES TO ACHIEVE NET ZERO/CARBON NEUTRALITY

Road administrations’ policies are in general linked to national net zero commitments andstrategies are therefore focussed on reducing emissions from their activities, while continuing
to deliver on the fundamental role of roads in maintaining the economic well-being of society.
There are some common themes in the strategic options being considered by NRAs to reduce
emissions. These include:
Transition to EVs: This is seen, by almost all national governments and road administrations
as one of the most important actions in the decarbonisation of transport sector. Progress has
been made and although there are barriers, in particular for LMICs, there is growing
recognition of the critical importance of this transition. For example, EV promotion has been

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included in the Indian Government’s24 National Electric Mobility Mission Plan (NEMMP) 2020,
which set out a roadmap to accelerate the adoption and manufacture of electric and hybrid
vehicles in the country, with the aim, among others of achieving national fuel security.
The transition to EVs25 and the gradual withdrawal of diesel and petrol cars is becoming an
integral part of the Net zero strategy through setting timeframes for a ban on sale of new
fossil fuel powered cars: Norway 2025, UK 2030, Canada, EU and California 203526. In India,
the move away from petrol cars has been extremely slow but the expectation is that lighter
vehicles (2 and 3 wheelers) will lead the transition, as happened in China 27.
EV (car) sales have grown dramatically in recent years, mainly in HICs but highest growth has
been recorded in China. Growth is, however, lagging in most other LMIC countries, with forexample, EVs forming only 0.5% of new cars in Brazil, India, Indonesia with the main barrier
to uptake being upfront costs, range, speed, battery life and battery technology. At the sametime, reducing reliance on it is also perceived as a means of improving fuel security.
For LMICs in particular upfront cost continues to be a major barrier. For example, Bhutan, an
LMIC, is facing a rapid increase in the number of cars (from 25,000 in 2000, to 89,300 in 2017
and 116,926 in 2021)28 which is a threat to its current ‘carbon negative’ status. While the drive
to EVs began in 2014, the number of EVs in the country currently stands at just 161. In addition
to other barriers, cost is a serious challenge, both for the provision of the infrastructure andthe purchase of EVs29.
Investment in building appropriate charging infrastructure has increased nationally (public
and private sectors) as well as by global agencies but there are significant barriers too. For
example, barriers in the UK30 include lack of an overarching strategy to enable provision of
sufficient charging infrastructure, restricted network (transmission and distribution) capacity
and supply of vehicles (particularly vans). A more detailed discussion on EVs is included laterin the Report.
••

Non-motorised transport (NMT) infrastructure: This includes mainly walking and cycling andis seen in both HICs and LMICs as providing significant contribution to decarbonising the road
networks (particularly in urban locations) and increasing social cohesion.
Road infrastructure solutions such as dedicated cycleways and safer junction designs are being
used to encourage active transport. Transport for London (UK)31 have an overarching goal ofachieving 80% of journeys in London to be made by walking, cycling or public transport.

24https://policy.asiapacificenergy.org/node/2663#:~:text=The%20National%20Electric%20Mobility%20Mission,on%20year%20from%2020

20%20onwards.
25 International Energy Agency (IEA). Global EV Outlook 2020. Entering the decade of electric drive?
26 Factbox – fossil fuel-based vehicle bans across the world. Thomson Reuters Foundation. November 2020.
27 KPMG (2020), Shifting gears: the evolving electric vehicle (EV) landscape in India, Shifting gears: the evolving electric vehicle (EV) land KPMG India (home.kpmg)
28 Chow Ping (2022). Electric vehicles are Bhutan’s answer to air pollution.
29 Zhu D, Patella DP, Steinmetz R, Peamsilpakulchorn P (2016). The Bhutan electric vehicle initiative. The World Bank Group.
30 Terri Wills (2020). The UK’s transition to electric vehicles. Climate Change Committee.
31 Mayor’s Transport Strategy, 2018. Mayor of London. Mayor's Transport Strategy (london.gov.uk)

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Netherlands is a leader in the provision of dedicated road infrastructure for cycles and is
working on 30 new projects across the country. The terrain (mainly flat), cultural and politicalfactors as well as central government help with financing have contributed to this success.

Germany built its first cycle highway in 2015 and has since moved to a more ambitious project,a 3.65m wide, fully lit 100 km long bicycle autobahn connecting 10 cities in the Ruhr region.
The distance between cities in this region is less than 10 miles, making it ideal for commuting
by bicycles. In addition to health benefits, this project is predicted to remove 50,000 cars every
day from the road network, equivalent to 16,000 tonnes of carbon emissions. Norwegian
government has also recently unveiled its plan to invest £700m in bicycle highways.
The actual share of non-motorised transport in cities in LMICs is most often higher than thatof similar sized cities globally. For example, in India, Surat has the greatest share of walking
and cycling (55% for a population of 2.4 million), while Bangalore has the lowest (25% for a
population of 8.6 million) in comparison to London (14% with a population of 6.6 million)32.
However, another major barrier in LMICs is that as motorisation has increased, safety ofpedestrians and cyclists has been impacted, particularly the urban poor who are dependent
on these modes. Around 12% of reported road fatalities are reported to be pedestrians andcyclists but the WHO in fact estimates this number to be much higher33.
While growth of NMT in LMICs is being held back by cultural factors (car ownership is new andgrowing, and is a status symbol) as well as the quality of the infrastructure (e.g. poor roadsurfaces and connectivity) and the environment (e.g. pollution), safety and risk, there are also
examples of good practice as illustrated with two examples from India and Kenya:
India: NMT is the preferred transport mode for much of the population in India due to its
affordability, although in recent decades cities have been experiencing a decline in the use of
NMT. There are several underlying causes including a growth in and greater focus on
infrastructure for motorised transport and increasing accident rates for pedestrians andcyclists. At the same time there has also been a growing recognition that while per capita
emissions in India are low, emissions from the transport sector are on an upward trajectory
leading to increasing pollution and health impacts from the higher consumption of energy
from non-renewable sources. This has led to efforts by the Government of India to coordinate
policies at the national level to achieve a sustainable transport system and build the capacities
of cities to improve mobility with lower CO2 emissions34.
The Institution for Transportation and Development Policy (ITDP) in India has been working
with cities to design and implement sustainable transport policies, e.g. helping the City ofChennai to develop India’s first NMT policy35. The Chennai Corporation adopted the policy in
32 Pai, M. (2007), Transport in cities - India indicators, India-Integrated-Transport-Indicators-EMBARQ.pdf (wrirosscities.org)
33 WHO (2018) Global safety report on road safety. Global status report on road safety 2018 (who.int)
34 Tiwari G and Jain D (2013). Promoting low carbon transport in India. NMT Infrastructure in India: Investment, policy and Design. UNEP.

ISBN 978-87-92706-19
35 2-Training-manual-MAQ3-NMT.pdf (sdabnca.org)

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2014 and this resulted in the Corporation mandating 60% of the city’s transport budget forthe construction and maintenance of NMT. In addition, they have worked to change attitudes
to car-free Sundays, tactical urbanism and education programmes for policy makers. By 2018,
120km of pavements and public bike-sharing schemes (to improve last mile connectivity) had
been built, and work is on-going to transform 1,000 km of streets to be safe and accessible topedestrians and cyclists by 203036.
Kenya: NMT is the primary form of transport for a significant proportion of the population in
many African cities, mainly because motorised (and in general, safer) modes of transport are
unaffordable. Despite this, only 10% of countries in Africa have policies to promote walking
and cycling, compared with 64% in Europe. In Nairobi, for example, walking and/or cycling is
the primary mode of transport for around 50% of the population and despite being clean,healthy and efficient, has been in decline37.
Working in collaboration with the UNEP-led global programme, ‘Share the Road’, the Kenyan
Government developed and introduced its NMT policy in 2011. The policy was not only about
improving the NMT network but also ensuring that NMT facilities and areas were prioritisedfor investment, and that walking and cycling facilities were integrated within all new urban
road projects in Kenya. The Nairobi City County Government launched its NMT policy for
Nairobi in 2015. The policy proposed a range of measures including lower road speeds, newinfrastructure and traffic calming measures, awareness raising activity, enforcement andfinancial commitment to address the high numbers of pedestrian fatalities (70% of the 723
road traffic fatalities in Nairobi in 2014) and also committed 20% of existing and futuretransport budget to walking, cycling and public transport infrastructure and services38.
Another major barrier to mass take-up can be the high cost of construction of dedicated NMT
infrastructure, ~ €2m/km (based on the German experience of cycle highways). This
compounds the difficulty of justifying the investments using standard methodologies. For
example, BCR for new highways are often driven by the benefits of journey time savings forlarge numbers of road users, including passenger cars and freight. Enablers of NMT
infrastructure include Government investment (e.g. German Government has kick started theprocess with an initial investment of 1.5 billion Euros) as well as incentives to encouragetransfer from cars to bikes ensuring safety on the cycle networks.
To advance the development of NMT in LMICs, UNEP (United Nations Environment
Programme) has supported the development of a project appraisal tool to evaluate the costs
and benefits of NMT, designed specifically for cities in developing countries 39. The aim is to

36 Chennai Non-Motorised Transport Policy (itdp.in)
37 Share the road – prioritizing walking and cycling in Nairobi - PPMC TRANSPORT (ppmc-transport.org)
38 Fact sheet: Non-motorised transport (NMT). www.fiafoundation.org
39 Cost benefit analysis of NMT projects. UNEP. https://www.unep.org/resources/report/cost-benefit-analysis-non-motorized-transport-

infrastructure-projects

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raise the profile for investment in NMT which is currently perceived as less important thanother transport solutions. Four case studies using scenarios in Nairobi, Kenya and training
workshops have demonstrated the capability of the tool to accurately and equitably appraise
investments in NMT in the African context.
•

Construction and maintenance of roads: The decarbonisation targets and the more recent
move to adopting a circular economy approach to road infrastructure design, construction andmaintenance has resulted in an impetus to achieve significant reductions in carbon in highway
projects. Globally there are many examples of new materials with reduced embodied carbon
and innovative methods to reduce use of virgin materials, etc. More details are provided in
Section 3.

Some high-level common threads running through the strategies being adopted by NRAs to
reduce emissions during the construction and maintenance of roads include:
•
•
•
•
•

Moving towards use of renewable energy as much as possible
Building in requirements for emissions reduction targets (including Scope 3 emissions) into thecontracts
Developing, publicising and making available carbon reporting tools to contractors covering
Tree planting programmes

New Zealand
The Ministry of Environment40 has proposed an Emissions Reduction Plan that will mandate
the reporting of energy use and embodied carbon on all new construction and maintenanceprojects and include aspects such as, using materials and processes that are net zero, resilient
to climate change, resource efficient (at use and in the future) and suitable for recycling, reuse
and repurposing at end of life.
SwedenLarge transport infrastructure projects (roads, rail, tunnels) are required to calculate andreport embodied carbon and monetary incentives are used to encourage the reduction ofembodied carbon below specified targets.
India
The country is investing heavily in expanding its road networks with current plans to increase
the size of its network by about a third in the next few years (representing approximately
40km of new highways per day). While decarbonisation is a key part of the long-term strategy,
in the short-term the focus is on the rapid expansion to support national economic growththrough the use of conventional methods of construction. However, there are elements that

40 Transitioning to a low-emissions and climate-resilient future: Emissions reduction plan discussion document. Transitioning to a low-emissions and climate-resilient future: emissions reduction plan discussion document | Ministry for the EnvironmentCARBON NEUTRALITY OF THE ROAD SECTOR

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support the principle of reduced emissions, e.g. since 2015, all new roads are mandated tohave LED lighting.
Overall, NRAs are looking into developing maintenance options to support decarbonisation
with more effort being put into identifying low carbon options. For example, smoothpavement surfaces with reduced rolling resistance can reduce fuel consumption and reduce
GHG emissions.
•

Encouraging public transport: The modal shift from private to public transport (buses, trains)
is a global ambition but a challenge both in HICs and LMICs. The transition, for example, tocleaner electric-buses can be challenging. Bloomberg41 reported that at the end of 2020, there
were around 598,000 e-buses globally and of these, 585,000 were in China. Government
subsidies combined with stringent city targets have enabled the transition in China. Other
LMICs are finding the cost of the transition a serious barrier and any progress may well require
coordinated action by international funding agencies.

In the UK for example, Government supported funding plans have helped to grow the numberof e-buses for use in towns and cities with a longer-term aim of stopping sales of buses
powered by fossil fuels, partly or wholly, by 2032 at the latest.
New EU policies aim to ensure that 25% of public sector purchased buses will be e-buses by2025, increasing to a third by 2030. Transformation to e-buses has been underway in
Netherlands for a long time and by the end of 2021, 81% of its fleet was electric. More rapid
progress is also being made in selected cities, with Paris, Berlin, London, Copenhagen,Barcelona, Rome and Rotterdam aiming to reach fossil fuel free buses by 2025.
Some limited progress, though slower, is also being made in some LMICs. UNEP is helping
African cities in their drive towards soot-free public transportation, including electric-poweredbuses42. The World Bank has been active in supporting the move to cleaner public transport
in South America with e-fleets being introduced in a number of cities across the continent43.
•

2.3

Decarbonisation of corporate emissions: In addition to the carbon emissions associated withconstruction, maintenance and use of the road network, National Road Administrations(NRAs) give rise to significant sources of carbon emissions from the operation of the road
network (lighting, tunnel operations, etc.), vehicle fleets, buildings, IT systems and employee
travel. Since these activities are under the direct control of the NRA, they are often an initial
focus for monitoring and decarbonisation.

QUESTIONNAIRE FINDINGS

A simple questionnaire was circulated, designed to capture information such as the adoptionof targets for reducing carbon emissions, the strategies being adopted and a willingness toparticipate in further discussions.

41 https://www.bloomberg.com/news/newsletters/2021-08-13/electric-buses-are-poised-to-get-a-u-s-infrastructure-boost
42 African cities turn to green buses in fight against pollution. UNEP. African cities turn to ‘green’ buses in fight against pollution (unep.org)
43 Electric buses: where are we? Electric buses and charging infrastructures in the world - IES-Synergy

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A total of 34 responses was received from 25 countries, including 8 LMICs. The geographicalspread and number of returns in each country are indicated in Figure 6.
Figure 7 confirms the high proportion of countries with a national target date for achieving
net zero (83% of the countries that provided a response) or carbon neutrality (54%).
Seventeen countries reported national targets for both carbon neutrality and net zero, whichperhaps reflects the interchangeable use over these terms. The importance of a nationaltarget date being in place is clear: in countries where a national target date for net zero is inplace, 60% of respondents reported a target date for the road administration. Similarly, wherea national target to achieve carbon neutrality is in place, 40% of road administrations had also
adopted a target date. Only one country reported having a target for the road administration
21econe there was not a corresponding national target.

Key:
Light yellow – 1 response
Light green – 2 responses
Dark green – 3 responses
Orange – 5 responses
Figure 6. Geographical spread of the questionnaire responses received

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Net Zero and Carbon Neutrality Policies
30

25

20

15

10

5

0
Yes
Figure 7. Responses indicating presence of net zero or carbon neutrality policies

Figure 8 shows that, irrespective of whether they have targets in place, NRAs are adopting a
range of strategies for reducing carbon emissions. A high proportion of positive responses wasseen in all areas, and 80-90% of those responding reported that fleet vehicles, roadmaintenance and road construction were areas that are being pursued.

NRA strategies to reduce carbon
25

Responses

20

15

10

5

0
Street Lighting

Fleet Vehicles
Yes

Road
maintenanceNo

No response

Road
Construction

Vehicles using
network

Not in remit

Figure 8. Strategies being adopted for reducing carbon emissions

Offsetting
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CASE STUDIES

While road administrations in most countries follow the policy direction set by their national
government, there are examples where NRAs have taken additional measures beyond theminimum requirements set out in the national policy to further reduce emissions. For
example, Norway44 has been making significant progress in greening infrastructure with zero
emissions construction sites (through use of fossil fuel free machinery), reducing or
eliminating carbon intensive materials etc.
2.4.1

National Highways: Net Zero Strategy

In response to the UK Government’s national Net-zero 2050 target, National Highways hasdeveloped and set out its Roadmap to Net Zero 2050 for the strategic road network in England,with interim target dates to achieve Net Zero in:•••

Corporate emissions
Maintenance and Construction
Road users

2030
2040
2050

44 Business Norway (January 2021). Norway is greening the construction Industry. Norway is greening the construction industry - The

Explorer

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Key actions that NH has identified to deliver its commitment to net zero include:
•
•
•
•
•
•
•
•
•
2.4.2

75% reduction in the company’s own carbon emissions by 2025
100% electric car fleet by 2030
Replace 70% of all lighting with LED by 2027
An extra three million trees planted by 2030
First net-zero road enhancement scheme by 2030
Develop a zero carbon 2040 roadmap for cement, concrete and asphalt by June 2022
Make digital roads an integral part of Road Period 2, and build this into Road Period 3 strategy
and beyond from 2023
By 2023, publish a blueprint showing how EV charging services should be provided on
motorways and major A-roads
By end 2022, report to Government on approach to zero carbon HGV trials on their roads
UK: Carbon neutral road improvement projectAn £8m carriageway reconstruction project in Cumbria, UK (reconstruction and resurfacing ofA590) was the first project in the UK that is carbon neutral by design45.
•

•
•
•
•
2.4.3

Early collaboration and carbon modelling experts working with Highways England and thescheme contractors and suppliers measuring the carbon benefits led to significant reductions
in carbon through materials reduction and reuse, lower energy consumption and efficienttransportation
The project resulted in 43% less carbon emissions compared to traditional working practices
Choice of materials and recycling on site reduced lorry movements and thereby delivered asaving of 230 tons of carbon emission
Solar powered generators and electric vehicles on site contributed to energy efficiency and asaving of 70 tonnes on carbon emission
A number of carbon credits (carbon credits discussed in more detail in 2.5) were obtained
throughout the project enabling carbon neutrality at finish
Canada: Carbon neutral major reconstruction project

The remodelling of a major motorway junction (6-year, C$3.7bn project) serves todemonstrate that large, complex projects can be delivered in a carbon neutral way. 80% of
the project was delivered by the contractor under a design and build contract, much against
the norm in North America, but very conducive to innovation and designing to need.
•••

The motorway junction, which carried about 300,000 vehicles per day had reached its end oflife and the Quebec Transport Ministry decided to deliver ‘more than a direct replacement’
The construction site measured 7 km by 3 km and involved rebuilding 145 km of traffic lanes,
as well as creating 10 km of bus lanes and 8 km of new cycle lanes
Traffic was kept moving throughout the work by persuading users to use mass transit; reserved
bus lanes and a new bus terminal enabled free flow

45 Designing ’UK first’ carbon neutral road improvement project. 2021. https://www.amey.co.uk/bolder-steps-together/our-social-value-

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•
•

•

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Continuous and up to date communications with stakeholders, including residents was needed
and was maintained throughout the project
Earthworks were a major part of the challenge, 8 M.m3 of material was moved, and about 65%of the soil was dried out with lime to allow it to be re-used
The main Canadian National Railway corridor, with 4 railway lines and carrying 50 trains a day,went right through the middle of the site. The work required 7 km of railway track to be
relocated. All work was carried out without any disruption of train services
This was a long and complex project that took 6 years to complete. From the information in
the public domain, there is no mention of carbon neutrality as an initial ambition. Instead,
there was a target for recycling (80 to 85%) which was exceeded with 95% of materials fromthe site being reused or recycled. In addition, the 148,500t of CO2 emitted during the project
was offset by a combination of planting trees and carbon credits.

The project itself was therefore finally delivered as a carbon neutral project and in addition
created 31 ha of green space which has been planted with 61,000 shrubs and 9,000 trees,from what used to be a concrete jungle.
2.5

PROCUREMENT OF LOW CARBON OPTIONS

2.5.1

Contract Specifications

Procurement is a powerful strategic tool in enabling organisations to bring together technicaland functional requirements in the acquisition and delivery of goods and services. NRAs, as
public bodies with substantial purchasing power have recognised that they can and have toplay a significant role in ensuring environmental sustainability by embedding appropriate
measures and assessment techniques within their procurement processes.
The EU has developed a set of Green Public Procurement (GPP) documents to encourage theinclusion of green requirements within a wide range of public procurement areas. The
documents aim to facilitate the preparation of tender documents such as specifications andtender evaluation documents where procuring authorities can incorporate all or some of therecommendations with the aim of providing a balance of technical performance,
environmental performance, cost consideration and market availability. Technicalspecifications outline the minimum compliance requirements for tenders to meet, and it isvital that the characteristics of the work are clear and understood by all operators. In 2016
the EU GPP criteria for Road Design, Construction and Maintenance was published to provide
guidance to public authorities on the achievement of higher environmental standards in the
procurement of road projects46.
In 2017, SPP (Sustainable Public Procurement) Regions published a Best Practice Report on
Performance/Output Based Specifications to provide guidance on the use of performancebased contracting, facilitating a move towards SPP and has received funding from the

46 Garbarino E., Rodriguez Quintero R., Donatello S., Gama Caldas M. and Wolf O.; 2016; Revision of Green Public Procurement Criteria for

Road Design, Construction and Maintenance. Technical report and criteria proposal; EUR 28013 EN; doi:10.2791/683567

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European Union’s Horizon 2020. The focus of performance-based specifications is on therequired outputs from a contract rather than specifying inputs, encouraging innovation by
giving contractors freedom to determine how to meet the specific requirements of thecontracting authority47. Output based specifications provide tenderers scope to suggest
innovative solutions or materials, while also achieving minimum required technicalperformance. Allowing for a collaborative approach from the beginning, as part of the pretendering phase, conversations with market stakeholders can be insightful to gain knowledgeof materials/methods/processes available on the market to aid the development ofspecifications to produce better outcomes and reduce time scales. Early engagement withstakeholders is crucial. Appropriate training needs to be provided to personnel preparing
tender documents to ensure a sufficient level of expertise in sustainable procurement andperformance/output-based specifications48. Where environmental indicators are embedded
into functional specifications within the tendering process, monitoring systems can be put inplace to report on progress, track and demonstrate improvements and to adopt innovative
solutions for use, reuse and repurposing of materials, or waste minimisation.
In the EU, for the evaluation of tenders, the criteria for assessment depends on the natureand complexity of the project and the tendering procedure. The assessment can be based on
pass/fail criteria or a more complex numerical scoring methodology to rank tenderers. The
contract is often awarded to the Most Economically Advantageous Tender (MEAT),
considering one of the following approaches:•••

Price only
Cost effectiveness (e.g., life cycle costing)
Best price/quality ratio taking account of qualitative social aspects

The cost effectiveness approach allows for the consideration of the operational costs, end oflife related costs and environmental costs, as well as the direct cost of works.
The Netherlands was the first European country to formalise the process for sustainableprocurement, with the Dutch Government establishing clear goals as early as 2005 andembedded this further into their procurement processes in 2010 when the Dutch House ofCommons ruled that all public authorities must implement 100% sustainable procurement by
2015.
In response to this, Rijkswaterstaat (the Department of Public Works of the Ministry of
Infrastructure and the Environment) developed a methodology for infrastructure projects
where the functional specification of the tender together with the quality input from the client
ensure an innovative and high-quality solution. The criteria that formed the basis of assessing

47 Douglas, A., 2017, Performance/Output Based Specifications - Best Practice Report, SPP Regions Project Consortium, ICLEI – Local

Governments for Sustainability, European Secretariat (SPP Regions: Publications)48 Douglas, A., 2017, Performance/Output Based Specifications - Best Practice Report, SPP Regions Project Consortium, ICLEI – Local
Governments for Sustainability, European Secretariat (SPP Regions:: Publications)CARBON NEUTRALITY OF THE ROAD SECTOR

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the sustainability attributes of tenders were CO2 emissions and environmental impact. The
following two tools were developed to measure CO2 emissions and environmental impacts,
and are now mandated to be used by all tenderers:••

The CO2 performance ladder – a certification system with which a tenderer can show themeasures to be taken to limit CO2 emissions within the company and in projects, as well as
elsewhere in the supply chain“DuboCalc” – a life-cycle analysis (LCA) based tool which calculates the sustainability value ofa specific design based on the materials to be used. Bidders use DuboCalc to compare different
design options for their submissions. The DuboCalc score of the preferred design is submittedwith the tender price

Rijkswaterstaat (RWS) has identified the role that procurement can play in focussing delivery
on the core objectives, creating a scale for suppliers and achieving a consistent and long-term
commitment to sustainability goals49. The scale and long-term approach are beneficial tosuppliers and enable investment in improved technologies and approaches.
The Conference of European Directors of Roads (CEDR)50 funded project “Circular Economy inRoad Construction and Maintenance” (CERCOM)51 is currently developing an inventory of thesystems / approaches appropriate at different stages of the journey towards circularity.
CERCOM is investigating how a circular economy (CE) could work in the context of highway
construction and maintenance and what barriers and opportunities exist for its adoption. Oneof the aims of CERCOM is to deliver an innovative risk-based framework and management tool
to facilitate a step change in the adoption of resource efficiency and circular economy
principles in procurement and multi-lifecycle management by NRAs. As part of the project,deliverables, guidance, training seminars and on-line materials for managers and practitioners
will be provided to aid in the move from a linear to circular economy.
2.5.2

Financial incentives / models

Carbon reductions are often considered by road operators in terms of implementation ofEnergy Conservation Measures (ECMs), with the idea of reducing carbon cost while also
improving profitability. The implementation of such ECMs often requires large capital
investments to be made, or the application of drastic measures to achieve operational
efficiency improvements. Such costs often outweigh the benefits of the carbon reductions,causing road administrators to reconsider the feasibility of these initiatives.
As an additional motivation to promote the uptake of ECMs across industries including roadinfrastructure, many governments have introduced financial models and tax incentives toincrease the pace at which ECMs are introduced. This section of the literature review will

49 Versteeg (2019) Dutch procurement approach for a more sustainable infrastructure. Presentation to the International seminar on

Asphalt Pavements 4-5 May 2019.).
50 CEDR (2020), https://www.cedr.eu/peb-call-2020-resource-efficiency-and-circular-economy)
51 Circular Economy in Road Construction and Maintenance - CERCOM (cedr.eu)

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examine financial incentives and models aimed at achieving carbon reductions and carbon
neutrality in LMICs and HICs, both at a government and road operator level.
Carbon Pricing – a general overview
Carbon pricing is an instrument that is intended to capture the external costs of greenhousegas (GHG) emissions, i.e. the consequences of emissions that the public pays for, such as
damage to crops, health impacts from heat waves and droughts, and loss of property fromflooding and sea level rise. It is meant to tie them to their sources through a price, usually inthe form of a price on the CO2 emitted52. A price on carbon aims to help shift the burden forthe damage from GHG emissions back to those who are responsible for it but can avoid thecosts of the damage caused. Instead of dictating who should reduce emissions where andhow, a carbon price provides an economic signal to emitters, and allows them to decide toeither transform their activities and lower their emissions or continue emitting and paying fortheir emissions. The two most common types of carbon pricing are emissions trading systems(ETSs) and Carbon Tax53.
An ETS – sometimes referred to as a cap-and-trade system – caps the total level of greenhousegas emissions and allows those industries with low emissions to sell their extra allowances tolarger emitters. By creating supply and demand for emissions allowances, an ETS establishes
a market price for greenhouse gas emissions. The cap helps ensure that the required emission
reductions will take place to keep the emitters (in aggregate) within their pre-allocated carbon
budget.
A carbon tax directly sets a price on carbon by defining a tax rate on greenhouse gas emissions
or, more commonly, on the carbon content of fossil fuels. It is different from an ETS in thatthe emission reduction outcome of a carbon tax is not pre-defined but the carbon price is.
An alternative mechanism for carbon pricing is an offset mechanism which designates the
GHG emission reductions from project- or program-based activities, which can be sold either
domestically or in other countries. Offset programs issue carbon credits according to an
accounting protocol and have their own registry. These credits can be used to meetcompliance under an international agreement, domestic policies or corporate citizenshipobjectives related to GHG mitigation.
Governments around the world are using sustainability tax measures to reduce emissions,meet their commitments on carbon neutrality and tackle climate change, as well as to raise
revenue and fund important policy objectives. While these goals are shared, the policies
established to achieve them vary greatly. For businesses that wish to act on climate change,
secure valuable incentives to enable these actions and avoid costly surprises, staying on topof the evolving sustainability tax landscape across the globe is critical. However, staying
52 What is Carbon Pricing? | Carbon Pricing Dashboard (worldbank.org)
53 Pricing Carbon (worldbank.org)

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current as policies rapidly evolve can be a challenge, especially for global businesses. Ernst
and Young (EY) offer a snapshot of sustainability incentives, carbon regimes, environmental
taxes and environmental tax exemptions present in 45 jurisdictions, through their EY GreenTax Tracker54.
Table 2. Countries surveyed under EY Green Tax Tracker54

ArgentinaColombiaHong Kong Luxembourg

Peru

South Africa

Australia

CyprusIndia

Malaysia

PolandSouth Korea

Austria

DenmarkIndonesia

MexicoPortugalSpain

Romania

Switzerland
TaiwanBelgium

Finland

Ireland

The
Netherlands

BrazilFranceItaly

New ZealandRussiaJapan

NorwaySingapore

Lithuania

The Philippines Slovakia

CanadaChina

Germany

UnitedKingdom

UnitedStatesThailandEuropean UnionTurkeyVietnamAt the time of writing, 27 of the 45 jurisdictions were implementing an ETS, while 11 had an
ETS under construction. 18 countries were currently implementing a carbon tax while 8 had acarbon tax under construction. 11 countries had both an ETS and a carbon tax system in place.
The green tax tracker also keeps a record of sustainability incentives, environmental taxes andenvironmental tax exemptions. 34 of the 45 countries currently offer incentives to switch toalternative fuels for vehicles / infrastructure. It should be noted that of the 44 countries(excluding the European Union) included, 28 are High Income Countries and 16 are Middle
Income Countries (12 UMICs and 4 LMICs).
Clearly there is a universal consensus on the application of carbon pricing to reduce carbon
emissions, but there are questions on the success of the strategy. There are few works thathave conducted an ex-post analysis, examining how carbon pricing has actually been
performed. A recent study55 has made several observations in this regard. First, most studies
suggest that the aggregate reductions from carbon pricing on emissions are limited—while
there is considerable variation across sectors, generally reductions range between 0% and 2%
per year. Secondly, in general, carbon taxes perform better than emissions trading schemes

54 ey-green-tax-tracker-edition-3-v3.pdf
55 Green, Jessica F. "Does carbon pricing reduce emissions? A review of ex-post analyses." Environmental Research Letters 16.4 (2021):

043004.

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30(ETSs). Finally, studies of the EU-ETS, the oldest ETS, indicate limited average annual
reductions—ranging from 0% to 1.5% per year. To set this in context, the IPCC
(Intergovernmental Panel on Climate Change) states that emissions must fall by 45% below
2010 levels by 2030 to limit global warming to 1.5oC56.
Overall, the evidence indicates that carbon pricing has limited impact on emissions. However,it should be noted that the current review has indicated that many countries are still in theirinfancy in terms of implementing actionable carbon pricing, with many countries starting off
with lower tax rates to leverage a policy evaluation approach which leverages economic
theory and machine learning for counterfactual prediction57. Abrell et al. used this method toanalyse the emissions and cost impacts of the UK CPS, a carbon tax levied on fossil fuel power
plants57. The results indicate that in the period 2013–2016 the CPS lowered emissions by 6.2%
at an average cost of €18 per ton. Again, with recent renewed focus in this domain, the relative
carbon reductions will be expected to increase in coming years. A common consensus in the
research is that the effectiveness of carbon pricing is heavily impacted by relative fuel prices.
The following sections examine some country specific incentives and sanctions at a closer
level.

56 Intergovernmental Panel on Climate Change 2018 Global Warming of 1.5 ◦C (World Meteorological Organization)
57 Abrell, Jan, Mirjam Kosch, and Sebastian Rausch. "How effective is carbon pricing? —A machine learning approach to policy

evaluation." Journal of Environmental Economics and Management 112 (2022): 102589.

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High and Upper Middle-Income Countries

Canada (HIC)
Canada’s sustainability tax programs at both the federal and provincial levels have been inplace for several years and continue to evolve. Over time, the two levels have worked together
to harmonise the application of environmental regulations including water, air, land andenvironmental assessment. In 2016, Canada adopted the Pan-Canadian Framework58 (PCF)
which focused on pricing carbon pollution, complementary actions to reduce emissions
economy-wide, adaptation and climate resilience, and clean technology, innovation and jobs.
There are currently federal sustainability funding programs, federal accelerated depreciation
for qualifying clean energy investments and several provincial sustainability programs, mosttaking the form of grants or rebates. Canada established a carbon pricing framework in 2018.
Flexibility was provided to provinces and territories to establish their own pricing plans with afederal backstop implemented if a local plan did not meet federal standards.
There are two systems operational in Canada59 according to the needs of the provinces.
Jurisdictions can implement (i) an explicit price-based system (a carbon tax like British
Columbia’s or a hybrid system comprised of a carbon levy on fuels and performance-based
emissions trading system like in Alberta) or (ii) a cap-and-trade system (e.g. Quebec).
Transport is Canada’s second highest carbon emitting sector, contributing 186 Mt CO2 per year
(25% of all emissions), behind the oil and gas industry which emits 191 Mt CO260. Nearly eighty
five percent of this sector’s emissions come from on-road transportation, and light-duty
vehicles alone count for half of the sector’s emissions. While greenhouse gas emissions fromthe light-duty vehicle sector have increased every year since 2015, it has also become thesector with the most advanced zero-emission vehicle offerings in the entire market, making
these vehicles a key component of transportation decarbonisation. To tackle this issue, theCanadian Government has set aside funding of CAN$400 million for zero-emission vehicles(ZEVs) charging stations, in support of the Government’s objective of adding 50,000 ZEV
chargers to Canada’s network. In addition, the Canada Infrastructure Bank will also invest$500 million in ZEV charging and refuelling infrastructure. The Government will also put inplace a sales mandate to ensure at least 20 percent of new light-duty vehicle sales will be zeroemission vehicles by 2026, at least 60 percent by 2030 and 100 percent by 2035. To reduce
emissions from medium- and heavy-duty vehicles (MHDVs), the Government of Canada aim
to achieve 35 percent of total MHDV sales being ZEVs by 2030. In addition, the Government
will develop a MHDV ZEV regulation to require 100 percent MHDV sales to be ZEVs by 2040

58 https://scics.ca/en/product-produit/pan-canadian-framework-on-clean-growth-and-climate-change/#:~:text=The%20Pan%2DCanadian%20Framework%20has,clean%20technology%2C%20and%20create%20jobs.
59 https://www.canada.ca/en/services/environment/weather/climatechange/pan-canadian-framework/guidance-carbon-pollution-pricingbenchmark.html
60 2030 Emissions Reduction Plan – Canada’s Next Steps for Clean Air and a Strong Economy - Canada.ca

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for a subset of vehicle types based on feasibility. The ZEV standard is undertaken at a Federal61
and Provincial level, with Québec the first Province to have one62.
South Africa (UMIC)South Africa is the 14th largest greenhouse gas emitter in the world and has a prominent roleto play in resolving climate change63. Section 12L of the South African Income Tax Act contains
an Energy Efficiency Saving initiative which provides an opportunity for South Africanbusinesses to apply for and benefit from a tax incentive for measured and verified energy
efficiency savings. The incentive is administered by the South African National Energy
Development Institute (SANEDI) that has the role of implementing and overseeing theapplication process of the incentive64. Any consumer of energy in South Africa that
implements an ECM is eligible to apply for this benefit. The incentive began on the 1st
November 2013 and is currently running to 1st January 2023. The Act provides for an additional
allowance in respect of energy efficiency savings at a rate of 0.95 Rand per kWh of measured
and verified energy efficiency savings65. An audited approvals process is engaged for each ECM
and the associated energy savings are calculated. The tax benefit is then claimed as adeduction in the company’s income tax return. The incentive is designed to mitigate theimpact of the first phase of carbon tax as more than 70% of South Africa’s emissions are energy
related65.
In addition to the section 12L incentive, South Africa’s Carbon increased to R144 (about
US$9.27) per tCO2e, effective from 1 January 2022. This rate is low in comparison withinternational commitments. The intention is to give large emitters time to transition to lower
carbon practices. To uphold South Africa’s COP26 commitments, the rate will increase eachyear until it reaches US$20, and from 2026, the South African government intends to escalate
the carbon price more rapidly every year to reach at least US$30 by 2030, and US$120 beyond
205066. Effective carbon rates are highest in the road sector, which accounts for 10.7% ofSouth Africa’s total CO2 emissions from energy use.
A recent study has shown that carbon pricing has a relatively low impact on emissions in theroad transport sector in South Africa67. This is mainly because a separate projection was madefor carbon pricing on synthetic fuels, which accounts for most carbon emissions from roadtransport.

61 chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://emc-mec.ca/wp-content/uploads/ZEV-Standard-Best-Practices-EN-

FINAL.pdf
62https://www.environnement.gouv.qc.ca/changementsclimatiques/vze/index.htm#:~:text=La%20Loi%20visant%20l%27augmentation,natio
nale%2C%20le%2026%20octobre%202016.%E2%80%99
63 Section 12L Energy Efficiency tax incentive applications on the rise (esi-africa.com)
64 Section 12L Energy - Efficiency Savings - SA Institute of Taxation (thesait.org.za)
65 Incentives can help companies address the challenge of climate change (deloitte.com)
66 South Africa's carbon tax rate goes up but emitters get more time to clean up (theconversation.com)
67 Carbon Pricing in Times of COVID-19: Key findings for South Africa (oecd.org)

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Lower Middle-Income Countries

Other incentives and carbon taxes have been in place across LMICs for several years.
India (LMIC) has well established sustainability tax programs, primarily at the national level,
though there are also local taxes on fuels and incentives granted for clean energy initiatives.
There is no formal carbon tax, but there are high taxes on petrol and diesel, which haveincreased sharply since 2014 and are possibly the highest in the world at over 100%
(combining the impact of excise duties and value added taxes). Additionally, there are lower
taxes on electric vehicles, only 5% goods and services tax vs. 28% for internal combustion
powered vehicles. There are fiscal measures proposed that would incentivise domestic
manufacturing of ACC batteries, manufacturing of solar panels and other qualifying activities.
Also, the government has approved a proposal to levy a “Green Tax” on old vehicles which arepolluting the environment. A Production Linked Incentive (PLI) scheme has been proposed toboost domestic manufacturing capabilities of the automobile industry, including electric andhydrogen fuel cell vehicles54.
In Indonesia (LMIC), the government has stated plans to introduce a carbon tax. Under
Indonesia’s Proposed Tax Bill that is still being reviewed and discussed by the Parliament,
carbon emissions having a negative impact on the environment will be subject to a minimum
carbon tax of IDR 75 per kilogram of CO2e or other equivalent measurement unit (equivalent
to around US$5.2 per tCO2e).
In Vietnam (LMIC), sustainability tax programs, mostly at the national level, have been
established for a quite long time with a Natural Resources Tax in place since the 2000s andEnvironmental Protection Tax since 2010s. However, new measures are still emerging. The
Law on Environmental Protection will come into force from 1 January 2022. Additionally, theVietnamese government is actively working to implement new measures and will release thedetailed guidance on an emission trading system soon. The government has also enacted
incentives and assistance for business activities related to environmental protection to
encourage enterprises to seize opportunities from sustainability, clean energy transition andwaste reduction54.
2.5.5

Business models

Business models underlying the management of highway networks are fundamentally basedon a linear approach, ‘Take, Make, Waste’ or Cradle to Grave. Over the last decades assustainability and the need to reduce carbon emissions have grown in importance, NRAs, tovarying degrees, have adapted their approaches to take on board aspects such:••••

External costs associated with the management of road networks, e.g. emissions
Carbon footprint of activities
Use of recycled and secondary materials
Life Cycle Analysis inherent in decision making

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The transition to carbon neutrality requires a fundamental change in approach to value chains,and for new Business Models that address the key principles of the circular economy, a cyclical
Cradle to Cradle approach, i.e., not just minimising resource consumption but designing out
waste and pollution, keeping products and materials in use for as long as possible. One of theaims would be to enable an increase in resource efficiency to be underpinned by a reductionin the use of primary materials.
The move to carbon neutrality is in the very early stages and while some NRAs have madeprogress with regards to some of the attributes related to circularity, there are no examplesof the adoption of a circular business model by any NRA. Essentially, NRAs still function withlinear business models, with a greater bias towards ‘lowest first cost’ considerations.
Circular business models contribute to carbon neutrality by reflecting the fundamental
principles underlying carbon reduction and key attributes are expected to include:
•
•
•
•
•
•
•
•
•

Designing out waste and pollution at the design stage
Materials management approach that supports value retention rather than a waste
management approach
Innovative ownership models, including for example provision of infrastructure as a service
Early contractor involvement
Extended contractor/supplier responsibility, with responsibility extending to end-of-lifeoptions for products, materials etc
Incentivising innovations and enabling risk and benefit sharing
Focusing on outcomes rather than outputs
Mitigating climate change impacts
Reducing consumption of new resources

While the transition from a linear to a circular business model is yet to make a mark withrespect to the construction and maintenance of roads, there are good practice examples from
NRAs testing options within individual projects that are precursors to the transition. For
example, pilot projects have been used to test the feasibility and learn lessons fromintroducing aspects relevant to CE based Business Model:
•
•
•
•

2.6

Infrastructure as a service contract – pilot project in Netherlands
Early contractor involvement to identify and collate opportunities for circular approach –major projects in the UK
Innovative solutions for reuse of ‘waste’ materials in road maintenance – project in Finland
Resource Exchange Mechanism – development in the UK contributing to mitigating resource
scarcity

LESSONS FROM RAIL SECTOR

As with highways, the rail sector also has targets for decarbonisation. Whilst noting thedifferences in the sector, specifically that the rail sector has control over the vehicles using the
network and tends to have large sections of the network which are electrified, rail operators

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also operate large infrastructure networks, and there is potentially valuable information toshare. Below is a summary of good practice implemented by rail operators.
Eurostar (UK, France, Belgium, Netherlands)
Eurostar measure CO2 across their entire operation (depots, contact centres, stations andoffices). They have targets to reduce CO2 and track it through Greenstone carbon data
management system. This has enabled them to become accredited to the Certified Emissions
Measurements and Reduction scheme (CEMARS). This certification covers CO2 emissions
associated with the UK operations. They are certified to ISO15001:2011 which is energy
management certification, and 14011:2005 for general environmental certification. From
2020, they are planting a tree for every service that runs – around 20,000 trees per year across
UK, France, Belgium and Netherlands68.
Eurostar has a 10-point plan from 2018 where they committed to science-based targets forthe energy efficiency of their business. In accordance with 2016 Paris Climate Agreement, they
are significantly reducing their corporate emissions to limit global warming to under 2 degrees
C.
Of the ones related to carbon, they plan to reduce train energy by 5% by 2020, have energy
meters on board and energy efficient driving by 2020, introduce alternatives to fossil fuelenergy for all journeys by 2030. The Netherlands section of their journeys is already 100%wind powered. They are conducting research into options for renewable energy at the depots
and are installing EV chargers at the UK depot, allowing purchase of EVs from 202069.
Transport for London (UK)
Transport for London (TfL) is one of the largest consumers of electricity in the UK, requiring
1.6TWh per year, the equivalent of around 420,000 homes. London Mayor, Sadiq Khan plans
to make London a zero-carbon city by 2030 and a programme is underway to procure
renewable Power Purchase Agreements (PPAs) – long term contracts direct with energy
generators that guarantee energy is supplied from renewable sources.
Work is also underway to develop a financing solution used to build wind and solar farms. A
fund will be created for public and private investors to invest directly into new renewables
projects, which will supply the GLA (Greater London Authority) group.
The first PPA will cover 10% of annual electricity use (guaranteed renewable power from
Spring 2022). Another PPA will cover a further 10% from renewable generation from ‘newbuild assets’70.

68 https://www.eurostar-treadlightly.com/en/environment.php
69 https://www.eurostar-treadlightly.com/en/tread-lightly-10-point-plan.php
70 https://airqualitynews.com/2021/04/01/mayor-of-london-announces-plans-to-power-tfl-on-renewables/#:~:text=TfL%20will%20shortly%20begin%20procurement,to%20TfL%20from%20Spring%202022

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Thalys (Netherlands, Belgium, Germany France)
From 2020 Thalys has been using electricity certified as being 100% green origin from windfarms and solar panels located in Belgium, France and Germany. The trains in the Netherlands
are operated entirely by wind power and have been since 2017. From 2010 to 2020, Thalys
halved their carbon emissions71. On green electricity and purchases, they state:“Faced with the impossibility of accessing 100% green electricity on its entire network, Thalys
has been committed to balancing its energy footprint through the purchase of certified
Guarantees of Origin since 1 January 2020.
By purchasing Guarantees of Origin, Thalys supports the production of green energy, which is
better for the environment and which is produced at the heart of its network, moreparticularly in Belgium, France, and Germany”72.
Netherlands – ProRail (infrastructure manager) and NS Dutch Railways (passenger railway
operator)
ProRail is undertaking a range of activities, installing solar panels at stations, along the railway
and trialling solar panels integrated into noise barriers. Point heating using natural gas is being
replaced with electric point heating and diesel trains are being replaced by green electric,hydrogen or battery alternatives.
ProRail has an active energy policy looking at both their own and their transporters energy
consumption. They are installing LED lighting at 400 stations and sensors dim the lights if theydetect that there are no people on the platform. They are also transitioning to diesel freeconstruction sites and purchasing 100% green electricity and gas73.
On 1 January 2017, Netherlands became the first country to power every electric train run by
the NS Dutch railways on the Dutch rail network by wind energy. This has resulted in significant
reductions in electricity consumption per passenger kilometre. A saving of 1.43 bn kilogramsof CO2 by 2020 has been reported.
Danish State Railways (Danske Statsbaner (DSB))DSB is investing to ensure full electrification and conversion of fleet of trains and targetingzero emissions by 2030. They signed a 15-year loan of EUR400 million in 2020 to financeelectric rolling stock. DSB invests in trains, locomotives and workshops and Danish state
invests in the infrastructure including EUR 10 billion on new rolling stock, workshops and fullelectrification of existing lines74.

71 https://www.linkedin.com/pulse/thalys-full-speed-ahead-green-electricity-bertrand-gosselin/
72 https://www.thalys.com/fr/en/about-thalys/thalys-is-taking-action-for-a-sustainable-world
73 https://www.prorail.nl/toekomst/duurzaamheid/energie
74 https://www.themayor.eu/en/a/view/eur-500-million-to-accelerate-the-sustainable-transition-of-danish-railways-9837

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In 2022, the European Investment Bank signed a 25-year, EUR 500 million lending agreement
to help DSB finance the acquisition of 100 new electric trainsets, to begin operation in 2024.
Network Rail (UK)
Network Rail has a detailed plan for transitioning to a low emissions railway by 2050 from a2020 baseline (2045 in Scotland). They will use science-based targets based on the mostambitious target of limiting emissions for their operations to 1.5oC warming scenario. Thisimplies reducing their emissions by 98% by 205075.
For their Scope 1 (direct emissions from sources owned by Network Rail, e.g. heating buildings
or fuel for vehicle fleet) and Scope 2 emissions (indirect emissions from the electricity, heator cooling purchased), they will source all non-traction electricity from renewable sourcesfrom 2020, transitioning their road fleet to ultra-low emissions. Network Rail operate therailway infrastructure, but not the trains themselves. The train operating companies operate
the vehicles, which fall outside of Network Rail’s control (scope 3) so they will work with the
supply chain so by 2050 at least 75% will have their own science-based targets, and with the
UK Government to enable traction diesel to be reduced by at least 27.5%% by 2030. They arelooking to use solar at stations and lineside, including direct supply trials (Riding Sunbeams).
Currently, they state that traction electricity is sourced from zero carbon nuclear energy. This
indicates the importance of system limits since, given the large amounts of embodied carbon
in nuclear plants, it could be argued that it is not truly zero carbon. They have specific interim
targets for 2020 – 2029 and then 2030 – 205076.

75 https://www.networkrail.co.uk/wp-content/uploads/2020/10/Our-ambition-for-a-low-emission-railway-Science-based-Targets.pdf
76 https://www.networkrail.co.uk/sustainability/a-low-emission-railway/CARBON NEUTRALITY OF THE ROAD SECTOR

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Indian Railways (India)
Indian railways is one of the largest railways in the world, one of the largest consumers ofelectricity in the country and responsible for 4% of the country’s total emissions. It has set an
ambitious target of achieving net-zero by 2030 with a detailed multi-faceted strategy77. In
addition to redevelopment and upgrading of assets, the key approaches include78:
•

•

•

•

2.7

Electrifying the complete network by the end of 2023; according to the Railway ministry, with
42,354 route kilometre having been electrified, as of January 2021, the Government has
achieved 66% of its overall target (e.g. between 2018-2019, more than 5000km of rail were
electrified, compared to 251 km in the UK)79
Using solar power to meet its electricity needs with a stated ambition to install 20 gigawattsof solar for both traction loads and non-traction. This will include building massive solar power
plants on its vacant land. During the coronavirus disease (COVID-19) pandemic, the railways
built a 1.7-MW solar power plant in Bina, Madhya Pradesh, in July 2020, making it the firstsolar energy plant in the world to directly power railway overhead lines, from which
locomotives draw traction power. Work has started on a second 2.5-MW solar project withstate transmission unit as well as on a third pilot with a capacity of 50 MW
In addition to traction power, solar panels have been installed at over 960 stations to meet
railway station energy needs. Bids have also been submitted for 198 MW solar power panelson the rooftops of another 50 railway stations
Another innovative initiative is the installation of a first-of-its-kind 16kW solar power plant in
Sahibabad Railway Station that doubles as a platform shelter. This reduced the total cost of
the platform’s shelter and rooftop solar plants and provides solar power to meet the nontraction demand

POTENTIAL IMPACTS OF POLICIES AND STRATEGIES ON SOCIAL INEQUALITIESThe ultimate success of reversing/stopping further climate change will depend upon Net
Zero/Carbon Neutrality being achieved globally. Measures to achieve the transition will
succeed in delivering the desired outcomes only if they are seen to be fair and not contributeto increasing or introducing new social inequalities, both between and within countries.
Transport sector is the faster growing sector contributing to economic growth and it is also
the fastest growing major contributor to emissions in the developing countries. An evaluationby the Asian Development Bank projected that the large increase in motorised vehicles inthese countries (including 2,3 wheelers, cars and other light duty vehicles) meant that there
may well be a three- to five-fold increase in CO2 emissions from transportation in Asian
countries by 2030 compared with emissions in 200080.
Discussions at UN Climate Change Conference (COP26) gave clarity to the critical need to strikethe correct balance in the roles and responsibilities of different countries in achieving
77 Decarbonisation and the Indian Railways | Economic and Political Weekly (epw.in)
78 Indian Railways likely to become world’s first ‘net-zero’ carbon emitter by 2030 (downtoearth.org.in)
79 Decarbonization-of-Indian-Railways_full-report.pdf (climatepolicyinitiative.org)
80 AADB (2010). Reducing Carbon emissions from transport projects. 47170274.pdf

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decarbonisation. The current commitments are presented in Table 1. LMICs, in contrast to
most of the wealthy countries of today, did not benefit from the period of unrestrictedindustrialisation and therefore bear no historic responsibility for accumulated emissions. At
the same time, since these countries are more seriously affected by the effects of climatechange, there is an expectation that the ‘wealthier’ countries will shoulder what they perceive
as a fair share of the costs. This includes ensuring that any measures undertaken do not
impede their economic growth which is very much in the early growth phase in many
countries. For example, the announcement by India of a 20-year delayed Net Zero target year
at 2070 received mixed reactions:
•

•

•
•

The more countries that set delayed targets, rather than adopting science-based targets
consistent with the goals of the Paris Agreement, the lower the possibility of avoiding theworst consequences of climate change
It was welcomed as India had not committed to a target previously; its economy is still very
dependent on fossil fuels for energy consumption and as a heavily populated but strongly
growing economy, its energy requirements are expected to increase more than that of othercountries
The Indian government itself made it clear that the country was taking a responsible stand andwould need to incur considerable cost in meeting the target
As part of setting the target, the Prime Minister of the country also made it clear that thecountry expected the world’s developed nations to make available $1 trillion to finance thetransition

The disparities are not just between countries but within countries too, with regional
differences in wealth, income levels, facilities, climate, infrastructure etc. To succeed any
policy to instruments to enable transition to net zero or carbon neutrality will need to takeaccount of the social conditions, such as the additional financial burden of adapting to newtechnologies on the already disadvantaged sections on society. For example, in the UK,
Government funding for electric buses is seen as being more generous in England and Scotland
compared to what is available for Wales. There are also differences in the needs in urban andrural areas and the ban on fossil fuelled cars may have a disproportionate effect on rural areas,
with limited access to public transport and more dependence on car ownership for work andleisure purposes.
In recognition of the importance of addressing these very issues, the European Commission
has allocated 72.2bn Euros to support low-income individuals/firms from the additional costsof the Emission Trading System (ETS2) for the period 2025-203281.
An on-going discussion within the development of contemporaneous policies to achievecarbon neutrality is how the burden for reducing emissions should be shared, how to balance
responsibility and costs for historical emissions (that contributed to economic growth andwealth generation in some countries) and current emissions (where enforced reductions
81 Generation Climate Europe (2022). The road to net-zero is paved with social (in)equality.

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could disproportionately impact economic growth of poorer countries). This is particularly
relevant as HICs have, in general, well developed road infrastructure, whereas LMICs are in aphase of rapid expansion of theirs.
The 27th Conference of the Parties to the United Nations Framework Convention on Climate
Change (COP27) took place in November 2022. The overriding themes of COP27 were justice
and ambition. On the theme of justice, the conference concluded with a historic decision toestablish and operationalise a loss and damage fund to provide funding for vulnerable
countries where climate disasters and extreme weather affected their physical and social
infrastructures82. The fund for financial assistance has been sought for decades, and finallyachieving agreement at COP27 is a significant milestone83. A transitional committee withrepresentatives from 24 countries will be set up in 2023 to establish the best means to
implement the funding mechanism and determine the intended source of finance84.

82 COP27: Delivering for people and the planet | United Nations
83 What are the key outcomes of Cop27 climate summit? | Cop27 | The Guardian
84 COP27 - Results, Key Findings and Summary - DFGE - Institute for Energy, Ecology and Economy

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PART B – Technical Solutions
3 CONSTRUCTION AND MAINTENANCE OF ROADINFRASTRUCTURE
3.1

NEED FOR ROAD CONSTRUCTION

Road building generates carbon emissions from a variety of direct and indirect sources,
including85:
•
•
•
•
•
•

Construction work, such as land preparation, production of concrete, asphalt, steel and otherraw materials, and operation of construction plant and vehicles
Tree felling to make way for roads, reducing carbon capture
Ongoing maintenance and servicing
Provision of roadside lighting, traffic signals and tunnel operations
Increased mileage and higher vehicle speeds enabled by the additional capacity
Stimulation of further development that relies on motor vehicle transport as the primary mode
for travel and movement of goods

Whereas an effective system of road transport is vital for a flourishing economy, many
countries face a spiralling demand for road capacity, where the convenience and relative
affordability of road travel has led to increased vehicle ownership and increased road use.
Economic models justify the expansion of road capacity, construction of which further
underpins new developments (housing, business, retail) that are increasingly reliant on roadtransport. Use of these facilities fuels further vehicle use, and further increases demand forroad capacity.
In this situation, NRAs are faced with a difficult challenge to balance the demand for roadcapacity against the challenge of reducing carbon emissions. A strategy set out by the Welsh
Government86 in the UK includes a pause and review of existing proposals and a new
methodology for assessing the appropriateness of future road schemes. The terms ofreference for the review state that the priority and focus for road investment, in accordancewith the Wales Transport Strategy, are 87:•••

The avoidance of action which leads to increases in carbon emissions from operating,
maintaining and improving the road network, especially in the next 15 years when mostvehicles in use will still be powered by fossil fuels
The reallocation of existing road infrastructure to achieve a shift to sustainable and accessible
forms of transport
The adaptation of existing road infrastructure to cope with climate change

85 McNaught, D., (2021), “How roadbuilding projects create CO2 emissions and what can be done to reduce them?”, Infrastructure Blog,

Institute of Civil Engineers (ICE) 15th April 2021
86 Welsh Government (2021). “Net Zero Wales Carbon Budget 2 (2021-25)”
87 Sloman (2022) “Wales Roads: initial panel report” - https://gov.wales/wales-roads-review-initial-panel-report-html

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Investment which maintains the safety and serviceability of the existing road network incompliance with statutory duties
The improvement of biodiversity alongside major transport routes

Furthermore, the review considers the sustainable transport hierarchy when considering new
infrastructure (Figure 9).

Figure 9. The sustainable transport hierarchy87

These types of hierarchical approaches in road construction thinking can have significant
impacts in lifecycle carbon emissions.
3.2

ROAD MAINTENANCE AND LIFE EXTENSION

3.2.1

Pavements

An important concept of the circular economy which is sometimes overlooked is theimportance of “sweating the asset” or keeping assets in service for as long as possible. The
concept can be applied to any road infrastructure object (pavement, bridges etc.). However,
the effectiveness of regular maintenance on asset condition must also be considered: road
networks that have low levels of maintenance and high levels of deterioration will lead tohigher long-term maintenance and reconstruction costs, with associated higher CO2
emissions88. A pavement that is well maintained, smooth and in good condition will also leadto lower emissions from vehicles using the road. Over the lifetime of a highly trafficked road,the main impact in terms of emissions is from vehicles using the road. Embodied impacts fromconstruction are approximately 1% or 2% over a 30-year time period88. Deteriorated roads
with a rough and uneven surface, rutting, potholes and deteriorated joints all contribute torolling losses and increased CO2 emissions from vehicles. Regular maintenance and extending
88 Road Pavement Industries highlight huge CO2 savings offered by maintaining and upgrading roads. EAPA, EUPAVE and FEHRL, 2015,

eupave-eapa-fehrl-co2-savings-by-maintaining-and-upgrading-roads.pdf.

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the life of roads can take place as part of regular road asset management and form part of CO2
saving strategies88. The value of maintaining pavements in good condition has been describedby Mahoko et al89, where they report
Estimates of CO2 savings associated with increased emissions of between 20 andapplication of chip seal / crack seal 37%, depending on speed, on South
maintenance in place of thin overlay (per 1km African roads in poor condition, with an
4-lane highway)
IRI (International Roughness Index) of 8,
compared with those in good condition
Chip seal – 39.5 tonnes / kmwith an IRI of 1.
Crack seal – 45.1 tonnes / km
However,carbonimpactsvary
considerably for different maintenance options Considering the three preservation
treatments of thin overlay, chip seal and crack seal, CO2 emissions per lane mile have beenshown to be equal to 18.6 tonnes, 2.7 tonnes and 0.41 tonnes respectively90. These savingsare generally associated with significant reductions in manufacture of raw materials.
Considering a 4-lane, 1 km highway, this equates to values of 46.1, 6.6 and 1.0 tonnes per km,
respectively. This highlights potential savings associated with maintenance planning. It ishighlighted that these figures should be built into a detailed LCA (life cycle assessment)
methodology considering the number of reapplications over the service life.
3.2.2

Bridges

Bridges are a key element of transport infrastructure, and many bridges that were built in the
1950s-1970s are reaching the end of their design service lives. Replacing and building new
bridges requires the use of steel and concrete, the production of which results in significant
CO2 emissions. To reduce the yearly production rate of these materials and associated CO 2
emissions, there are 2 options91:••

Optimising design to use less of these materials during construction
Extending the service life of the structures

Studies have been conducted to examine the impact of methods of Structural Health
Monitoring (SHM) to increase the lifetime of bridges reaching the end of their design service
lives, thus reducing the CO2 emissions associated with repair/replacement91. SHM uses a
system of instrumentation and analysis to determine structural performance more accurately.
Raeisi et al. examined the impact of the application of SHM of two medium span steel girder
bridges built in the 1960s91. It was concluded that extending the lifetime of these bridges using
SHM reduced carbon emissions. Assuming the use of SHM extends the life of the bridges by
89 Mashoko et al (2014). Investigating the environmental costs of deteriorating road conditions in South Africa. Proceedings of the 33rd

Southern African Transport Conference (SATC 2014). Proceedings ISBN Number: 978-1-920017-61-3
90 Wang, H., Al-Saadi, I., Lu, P., & Jasim, A., Quantifying greenhouse gas emission of asphalt pavement preservation at construction and use
stages using life-cycle assessment. International Journal of Sustainable Transportation, 14(1), 2020, 25-34.
91 Raeisi, F., Algohi, B., Mufti, A., Thomson, D.J., Reducing carbon dioxide emissions through structural health monitoring of bridges, Journalof Civil Structural Health Monitoring, 2021.

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5-10 years, it is estimated that the CO2 emissions due to bridge reconstruction would decreaseby 9-17%91.
There are additional theoretical studies in the literature proposing LCA and LCC methods toevaluate and reduce the environmental impact of concrete bridges92,93. Increasing concrete
strength in design, optimising maintenance and the use of alternative materials are some of
the areas being examined in the literature to reduce associated CO2 emissions associated withbridges94,95,96,97.
3.3

LOW CARBON CONSTRUCTION

There has been significant progress made in carbon neutral construction and operation
practices. Many innovative road construction and rehabilitation projects have been carriedout in recent years aiming at reducing carbon emissions. The following examples will provide
some oversight.
A590, United Kingdom
In terms of low carbon road construction, the recent A590 dual carriageway resurfacing andreconstruction project is of note. The project was an £8m National Highways carriageway
reconstruction in Cumbria, UK.
Carbon modelling experts from Amey Consulting worked with National Highways andcontractors, including Aggregate Industries, A E Yates and HW Martin to measure the carbon
benefits of the scheme. The works resulted in significant carbon reduction across three mainareas; materials reduction and reuse, energy reduction and transportation efficiencies. As isoften the case in low carbon construction, early consultant and early contractor engagement
was critical. This allowed carbon efficient solutions to be developed and calculated through abespoke carbon calculation model. Key initiatives which reduced emissions during theconstruction stage included the ex-situ foam-mix recycling of existing road surface plainings,
by producing a site batched cold recycled asphalt. In total the project reduced carbon by up
to 43% compared to traditional road construction solutions and saved almost £3m.
The application of foam-mix recycling on site erased approximately 6,000 HGV movementsfrom the operation, saving 230 tonnes of CO2e. This also shortened the construction

92 García-Segura, T, Yepes, V., Frangopol, D., Yang, D., Lifetime reliability-based optimization of post-tensioned box-girder bridges,

Engineering Structures, Volume 145, 15 August 2017, Pages 381-391.
93 Gokasar, I., Deveci, M., Kalan, O., CO2 Emission based prioritization of bridge maintenance projects using neutrosophic fuzzy sets based
decision making approach, Research in Transportation Economics, Volume 91, March 2022.
94 Pedneault, J., Desjardins, V., Margni, M., Conciatori, D., Fafard, M., Sorelli, L., Economic and environmental life cycle assessment of ashort-span aluminium composite bridge deck in Canada, Journal of Cleaner Production, Volume 310, 10 August 2021.
95 Habert, G., Arribe, D., Dehove, T., Espinasse, L., Le Roy, R., Reducing environmental impact by increasing the strength of concrete:quantification of the improvement to concrete bridges, Journal of Cleaner Production, Volume 35, November 2012, Pages 250-262.
96 Xie, H. B., Wu, W. J., Wang, Y. F., Life-time reliability based optimization of bridge maintenance strategy considering LCA and LCC, Journalof Cleaner Production, Volume 176, 1 March 2018, Pages 36-45.
97 Asadollahfardi, G., Katebi, A., Taherian, P., Panahandeh, A., Environmental life cycle assessment of concrete with different mixed designs,
International Journal of Construction Management, 2021.

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programme, reducing road diversions and traffic management impacts which had added tothe carbon savings. In addition to the carbon benefits associated with the pavement solution,
significant carbon reductions were also realised as a result of energy efficiency measures. The
use of solar powered generators, lighting, signage, CCTV and catering facilities, along with theuse of electric vehicles saved approximately 70 tonnes of CO2e98.
During construction, contractors Aggregate Industries removed the top 32cm of the existing
pavement surface and used it to produce an ex-situ cold recycled asphalt. This was then mixed
with the contracting company’s SuperLow asphalt to make a carbon neutral paving surface. A
total of 50,000 tonnes of material was extracted from the original pavement, of which around38,000 tonnes was recycled over the course of just six weeks. This included roughly 11,500
tonnes of asphalt and 27,000 tonnes of foamix, which was laid using wide pavers. Aggregate
Industries said a further 20,000 tonnes would be reused on other projects99.
Concrete Pavements in the United States
Loijos100 assessed the life cycle impacts of concrete pavements and discovered that the levelof CO2 emissions varies widely depending on the type of road scheme, from 404 metric tons
CO2e/km for a local rural road to 6500 metric tons CO2e/km for an urban interstate, varying
by an order of magnitude. The large increase in emissions for highways/interchanges can be
attributed to the larger structures required and the road design (thicker concrete slab, wider
road etc.). For concrete pavements, CO2 emissions can be reduced by optimizing design andby replacing cement with secondary cementitious materials (SCM). These measures were
found to reduce emissions by 10% and 17% respectively, while also reducing construction
costs101.
A12, Netherlands
A further example of low carbon construction and implementation of the circular economy is
the A12 reconstruction between Ede and Grisjoord junction in Netherlands102. Rijkswaterstaat
used the Most Economically Advantageous Tender (MEAT) approach which enabled theselection of the bid that offered the best ratio of price to quality including assessment of CO2
mitigation and reduction of environmental impacts. In addition, the consideration of ‘use anddisposal’ at the planning and procurement stage of the project represented an explicit move

98 Designing ‘UK first’ carbon neutral road improvement project (amey.co.uk)
99 Tatum, A., (2021), “First carbon neutral road improvement project in the UK is completed”, Highways News
100 Loijos A (2011) Life cycle assessment of concrete pavements: impacts and opportunities. Massachusetts Institute of Technology.

https://dspace.mit.edu/handle/1721.1/65431
746765257-MIT.pdf
101 https://cshub.mit.edu/sites/default/files/documents/factsheet-pavements-UpdatedAug2018_FINAL.pdf
102 Jones, Sohn and Bendsen (2017b). Circular Procurement Case Study Collection. ICLEI – Local Governments for Sustainability, European
Secretariat, downloaded from https://sppregions.eu/fileadmin/user_upload/Resources/Circular_Procurement_Case_Study_
Collection.pdf?msclkid=b61465cdd14311ecba3e935ef3e6cf47 on 9/5/2022.

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by Rijkswaterstaat towards carbon reduction. Below are some outcomes and lessons learned
from the A12 relating to carbon neutrality:•••

CO2 emission reductions were achieved through design and materials choices, e.g., roadsurfacing materials that extended the standard expected product lifetime
Optimising product lifetime created greater whole embodied carbon benefits when comparedwith standard practices
Setting targets for environmental performance assisted in embedding carbon reductions in theearly stages of the project, particularly when considering long term contracts that include
maintenance, in-use management and disposal of assets/ infrastructure

Concrete Bridges in Sweden
Ekström et al. examined several concrete bridges in Sweden and proposed opportunities toreduce greenhouse gas emissions103. Figure 10 illustrates that the life cycle assessment of thelevel of emissions associated with the construction industry in Sweden is on par with that frompassenger cars. The production of steel and concrete for the construction of roads, railways,
bridges and other structures accounts for a large portion of emissions in the construction ofroads, as illustrated in Figure 11. The study examined measures that could be implemented
both in materials and in design and construction. For example, by including additives into
concrete mix designs and reducing the cement content, the carbon footprint can be reduced
significantly. The paper examined areas of design where reductions in environmental aspects
may be feasible. The study concluded that for a large reduction in climate impact in bridge
and road infrastructure construction, combined efforts of all stakeholders will be required.
Given the long design service life of bridges, most of the life cycle is post construction, so it isvital that a sustainable approach is followed in design and construction to reduce carbon costs
associated with maintenance and rehabilitation103. The client, as well as all parties involved in
the design and construction, need to follow a more sustainable approach to allow for a
reduction in carbon emissions in the construction and maintenance of road infrastructure 103.

103 Ekström, D., Al-Ayish, N., Simonsson, P., Rempling, R., Climate impact optimization in concrete bridge construction, et al (2017), 39th

IABSE Symposium, 2017.

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Figure 10. A comparison of CO2 emissions from the construction sector in Sweden (reproduced from 103)

Other
12%
Concrete
35%

Concrete
Reinforcing steel

Machines /transport
26%

Construction steel

Asphalt
Machines / transport
Other
Reinforcing
Asphaltsteel
5%Construction steel
10%12%

Figure 11. Distribution of emissions in the Swedish infrastructure sector (reproduced from 103)CARBON NEUTRALITY OF THE ROAD SECTOR

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The research shows that significant carbon savings can be made particularly through how
concrete is manufactured and specified for construction. Research shows that local roads andurban interstate concrete roads have a CO2 cost for construction of around 200 tonnes and1,083 tonnes per lane km, respectively104. It has been shown that cement contributes toaround 60% and 50% of this CO2 for local and urban interstate roads, respectively105. Again,
considering a 4-lane highway, a 10% reduction in cement content could result in carbon
savings of 49 tonnes and 217 tonnes of CO2, respectively.
3.4

CIRCULAR ECONOMY AND RESOURCE EFFICIENCYCircular economy (CE) and resource efficiency (RE) for road maintenance means, by design:••••

Minimising consumption of natural resources
Designing out waste and keeping resources in use and at their highest level of utility
Optimising the value obtained within each lifecycle
Improving environmental performance and contributing to societal development

Adopting an approach based on CE and RE has the potential to make a significant contribution
to decarbonisation, with road pavements inherently suited to reuse of materials. Asphalt
concrete is a fully recyclable material and Reclaimed
Estimates of CO2 savings associatedAsphalt Pavement (RAP) is widely used although significant
with 10% replacement of cement
challenges remain in reusing material at the same levelwith GGBS in road construction perrather than downcycling it into lower value applications
1km of 4 lane highway
such as replacing aggregate in unbound pavement layers.
Local Roads – 49 tonnes CO2/km
The proportion of RAP permitted in hot mix and warm mix
asphalt mixes varies considerably in different countries.
Urban Interstate – 217 tonnes
Studies have demonstrated the feasibility of producing
CO2/kmbituminous mixtures with a high (over 40% wt.) or very high (up to 100% wt.) proportion of
RAP, and negative perceptions can be addressed by good management practices to control
the quality of the RAP, novel production technologies and advanced mix design. Tarsi et al.106
recently reviewed the state of the art.
It is noted that while asphalt is fully recyclable, there is still ongoing research into innovative
methods, where additional materials (e.g. waste materials such as plastic or crushed glass) areadded to the binder or aggregate during construction. Research into the ability to recycle
these materials is ongoing, a factor that should be considered as part of multi-Life Cycle
Analysis prior to using non-traditional mixes.

104 Santero, N., Loijos, A., Ochsendorf, J., Greenhouse gas emissions reduction opportunities for concrete pavements, Journal of Industrial

Ecology 17.6 (2013): 859-868.
105 Loijos, Alex Alexander Nikos. Life cycle assessment of concrete pavements: impacts and opportunities. Doctoral Dissertation.
Massachusetts Institute of Technology, 2011.
106 Tarsi, G., Tataranni, P., Sangiorgi, C. The challenges of using reclaimed asphalt pavement for new asphalt mixtures: a review. Materials
2020; 13(18), 4052. https://doi.org/10.3390/ma13184052

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Circularity, however, goes beyond simply recycling and entails a fundamental re-evaluation of
how valuable resources can be used at their highest value, i.e., efficiently used, reused,
repaired, and repurposed, not just recycled. A key aspect is about designing out waste andpollution rather than addressing these downstream after they are produced or designing forreuse and repair. The overarching objective is not necessarily to minimise the cradle-to-grave
flow of materials, but to generate cyclical, cradle-to-cradle metabolisms that enable materials
to maintain their status as high-value resources.
Below are some examples of recent road construction projects where circular economy
approaches were followed.
A303, United Kingdom
The A303 Amesbury to Berwick Down scheme commission, undertaken between September
2017 and June 2018, was the first scheme in the UK that adopted circular economy
approaches from the preliminary design phase with the aim of raising awareness of,identifying and promoting circular economy approaches in the organisation 107. The approach
built upon the lessons learned from an earlier A14 Circular Economy Pathfinder Project:
•
•
•

•
•
•

•
•

Early design stages have the greatest potential to improve resource efficiency and contributeto circular economy
Identifying and implementing opportunities at this stage can enable significant reductions incost, waste and greenhouse gas emissions and other sustainability benefits
Over 100 opportunities for material, processes and environment / biodiversity gains wereidentified for the A303, and approximately one quarter of them were incorporated within thePreliminary Design
Communication materials to raise awareness of significant sustainability benefits including,
reductions in cost, waste and greenhouse gas emissions that CE initiatives can generate.
Lessons learned for moving forward with the transition to CE
Need to embed the key opportunities by for example developing a ‘live’ list, for review,
development, investigation and continue to, in collaboration with stakeholders, identify
further efficiencies and innovation
Use contractual mechanisms to take forward the key opportunities
Develop metrics to monitor and evaluate circular economy realisation and outcomes as wellas sustainable resource management activities with the longer-term aim of quantifying thebenefits realised and thereby helping to inform future work

Use of felt waste in road construction in Finland
The driver in this case was to enable CE through an innovative solution, developed by a local
company (Tarpaper), of using waste materials from another sector. The aim was to use roofing
felt waste in road construction and make this part of a normal procedure for the future. Pilot
areas were provided by the procurer, the City of Lahti, for testing. Roofing felt waste from107 Highways England (2018). A303 Amesbury to Berwick Down. Circular Economy Approaches at the Preliminary Design Phase. AECOM,

Mace, WSP HE551506-AMW-EGN-SW _ZZ_ZZ _ZZ-RP-EN-0006 P02, S4 (Report provided by National Highways)

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demolition or refurbishing was processed and added as a bitumen source in the production of
new asphalt. This exercise resulted in the production of quality asphalt with a reduced
requirement for virgin bitumen and beneficial use of roof felt waste for use in the road sector.
Outcomes and lessons learned108:
•

•

•

•

The innovator, Tarpaper Recycling Finland, was able to register a patent for the method torecycle roofing felt waste and thereby introduce a new environmentally friendly option forroad maintenance
The joint working between the City of Lahti and Tarpaper that resulted in accelerating the
successful use of roofing felt waste as a material for asphalt highlighted the need for acollaborative approach between procurers and suppliers.
The success of the approach catalysed the search and use for other materials to similarly
deliver environmentally friendly outcomes and reduction in carbon emissions. Anotherexample of alternative materials used in road construction projects is soil (extracted fromconstruction sites) and ash resulting in reduced costs due to shorter transportation distances
and the reduced need to purchase soil
In relation to circular economy and multi-life cycle analysis, it is important to recognise thechallenges and limitations of using innovative methods and materials. Research must be
progressed to determine the future recyclability of these non-traditional materials

Circular economy approaches in general have
Adoption of Circular Principles insignificant potential to induce both carbon andRoad Construction
economic savings in road construction andmaintenance. Transport Infrastructure Ireland (TII),
Savings of over €800,000 and 600t
the NRA of Ireland, have put forward a bespoke
CO2 across an 11km scheme
Circular Economy Plan based on the principles of the
9 Rs of circularity109. This plan has been tested in a pilot study at route selection stage for an
11.2 km section of the major national road network.
3.5

LOW CARBON MATERIALS

3.5.1

Asphalt

While traditional ‘hot mix’ asphalt is produced at temperatures between 120 C and 190 C,
it is now common for asphalt to be produced at lower temperatures110, namely:•••

Cold mixes, with unheated aggregate and bitumen emulsion or foamed bitumen
Half warm asphalt, produced between approximately 70 °C and 100 °C
Warm mix asphalt (WMA), produced between approximately 100 °C and 150 °C

108 Nordic Council of Ministers (2020). Pre-Study: Indicators on Circular Economy in Nordic Countries.
109 Lynch J. TII circular economy plan: TII standards training

https://www.tiipublications.ie/training/SRT22/day1/05_j_lynch_TII_circular_economy_plan.pdf
110 https://www.eapa.org/warm-mix-asphalt

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For lower temperature asphalts, additives or foaming techniques are used to reduce theviscosity of the bitumen so that it remains workable. A paper111 by the European Asphalt
Pavement Association quotes reductions of the order of 20 to 40% in plant stack emissions of
CO2 for half mix and warm mix asphalt, compared with hot mix, as well as reductions in othergreenhouse gases. The asphalt paving association of New Mexico also quotes112 a 20%
reduction in fuel consumption for warm mix, during manufacturing. The reduction in energy
use will be partially offset by the requirement for additives or additional processes. Lower
temperature materials have other benefits113 including a reduction in the production ofpotentially hazardous fumes and a longer working window and / or range of ambient
temperature for application. Extended service life is also claimed because of improved
compaction and reduced binder oxidation (due to the lower temperatures involved in
production). However, the cooler material benefits from modifications to the paving andcompaction process to achieve a good result.
In the Assam State of India114, a trial of 500 km cold mix asphalt showed the material to behighly suitable for local conditions. In this region, conventional hot processes are often
disrupted by intermittent rainfall and the transport of construction plant to site is complicatedby the hilly terrain. Conversely, cold mix is a practical alternative, requiring only simple, lowcost machinery, which was found to result in higher rates of construction under these
conditions. It was calculated that the fuel saving, compared with hot mix, would amount to
1,500 l/km, or 4,200 kg CO2 emissions per km constructed, a 90% reduction. Considering thescale of road building in India, if cold mix was adopted for the 50,000 km constructed per year
it would translate to 200 million kg reduction of CO2 emissions annually. The material isreported to be durable in service, due to the anti-stripping agents incorporated into the
mixture, although it has a higher initial cost. It is also seen as providing green employment
opportunities, particularly increasing the opportunities for female workers, with reduced
exposure to hazardous working conditions. The lifecycle considerations presented are
reproduced in Table 3.
Table 3. Lifecycle cost considerations forcold mix asphalt deployed in Assam(source 114)

Warm mix asphalt
Estimates of CO2 savings from using warm mix asphalt
in place of hot mix asphalt (per 1 km of 4-lanecarriageway)
Saving at construction – 8 to 16 tonnes

111 The use of warm mix asphalt, EAPA position paper, European Asphalt Pavement Association, Belgium, 2014112 https://apanm.org/warm-mix-asphalt-wma/
113 https://www.worldhighways.com/wh3/feature/reduced-temperature-asphalt-road-construction
114 Das, R. K., Bhushan, R., Boro, M. C., Agarwal, R., Cold mix – a “green” black-topping technology for rural roads delivering higher

durability and socio-economic and environmental benefits to society. 25th World Road Congress, Seoul, 2015

CARBON NEUTRALITY OF THE ROAD SECTOR

BlackCostof Usagecost
topping laying per concerns
type
m2 (in x
Rs)
Hot mix X

High fuel use
Pollution

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Safety, Health
costs
cost
& and
concerns
Environmental

Renewalafter 5 years

Temperature
control

Uses morebinderwhen
recycled

Productivity,
safety – low

Uses lessbinderwhen
recycled

Environmental
impact – minimal

Environmental
impact – highLimitations in use
Cold
mix

X + 15%

No fuel [needed] Renewal
for heating
after 7 years– presence ofGreen technology
anti-stripping
Extended paving agentswindow

Productivity,
safety – high

WMA materials are well-proven. Over 40 State highway agencies in the USA have adopted
warm mix specifications115 and, even in 2010, this technology was used to deliver 42 million
tons of material, nearly 12% of total asphalt production. In Europe, use of WMA approximately
doubled between 2013 and 2020, to over 8 million tonnes, although this represents only amodest proportion of total production of approximately 275 million tonnes116.
In 2021, England’s National Highways began asking all its suppliers to use WMA by default,
estimating117 that the 15% CO2 reduction compared with hot mix materials will save around60,000 tonnes of CO2 a year. As an approximate indication of the potential CO2 saving fromadoption of WMA, scaling the data from various sources118, 119, 120, 121 and assuming, where
necessary, that 450 tonnes of asphalt is required to surface 1 lane km of carriageway (3.6 m
width) to a 50 mm depth, suggests a saving of between 1 and 5 tonnes CO2 / lane km could
be attained compared with HMA. Taking data from a further study, suggested a saving of

115 https://www.fhwa.dot.gov/innovation/everydaycounts/edc-1/pdf/wmafnlweb.pdf
116 EAPA Asphalt in Figures - provisional figures 2021 https://eapa.org/asphalt-in-figures/
117 https://www.gov.uk/government/news/highways-england-accelerates-switch-to-lower-carbon-asphalts
118 Lu Y, Wu H, Liu A, Ding W, Zhu H Energy consumption and greenhouse gas emissions of high RAP central plant hot recycling technology

using lifecycle assessment. https://publish.illinois.edu/lcaconference/files/2018/01/32_Revised-Paper-ENERGY-CONSUMPTION-ANDGREENHOUSE-GAS-EMISSIONS-OF-HIGH-RAP-CENTRAL-PLANT-HOT-RECYCLING-TECHNOLOGY-USING-LIFE-CYCLEASSESSMENT%EF%BC%9ACASE-STUDY.pdf
119 Mazumder M, Sriraman H, Kim HH, Lee SJ. Quantifying the environmental burdens of the hot mix asphalt (HMA) pavements and the
production of warm mix asphalt (WMA). Int Journal of Pavement Research and Technology (2016) Vol 9, Issue 3, p 190-201
120 https://www.hanson.co.uk/en/blogs/low-energy-asphalt-the-future-roadworks
121 https://uploadstarmaccom.blob.core.windows.net/uploads/sites/2/2022/08/UltiLow-case-study-Birley-Spa-Lane-Sheffield-1-1.pdf

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between 18 and 32 tonnes CO2 / lane km, depending on the type of road122. This value issubstantially higher than other estimates, and the limited detail provided did not allow a
comparison to be made with the other sources. However, the difference that it is possible toachieve in practice will depend on the local situation, as they are influenced by the capability
and utilisation of plant, the type of energy source deployed, ambient weather conditions andthe moisture content of materials. The effective management of stockpiles to reduce moisturelevels can also have a dramatic influence on the energy needed for drying123.
3.5.2

Concrete

The production of cement and concrete results in a large amount of CO 2 emissions. Studies
have been carried out on processes and design procedures to reduce the environmental
impacts associated with concrete without compromising quality and safety.
According to Habert et al.124, using alternative fuels to produce concrete, improvements incement kiln and substituting clinker with alternative materials could have the effect of
reducing CO2 emissions associated with the cement industry by a factor of 2. Industrial byproducts such as pulverised fuel ash and ground granulated blast-furnace slag are examples
of standard clinker replacement materials in the production of cement in Europe. Limestoneor natural pozzolans are also used. These additions of supplementary cementitious materials(SCM) can also be made during concrete production rather than cement production. A project
funded by the Swiss Agency for Development125 is developing a limestone calcined clay
cement, name LC3, which could potentially reduce CO2 emissions by 30% compared tostandard cement mixes. Asadollahfardi et al.126 indicated that replacing cement with
Geopolymer resulted in a reduction in global warming indicator of nearly 26% compared with
Ordinary Portland Cement (OPC) concrete. A case study by Hossain et al.127 used life cycle
assessment techniques to evaluate the advantages of using volcanic ash as a potential
alternative SCM. The results indicated that for the same strength concrete, using volcanic ash
as a SCM has the potential to reduce GHG emissions by 25% and 19% compared to OPC andmore traditional SCM concretes. A study by Rangelov et al.128 assessed the impacts of reducing
cement and concrete volume in paving mixtures in the United States. As well as investigating
122 Lokesh K, Densley-Tongley D, Marsden G (2022) Measuring road infrastructure carbon: a critical in transport’s journey to net-zero

https://decarbon8.org.uk/wp-content/uploads/sites/59/2022/02/Measuring-Road-Infrastructure-Carbon.pdf
123 Simmons GH. Technical paper T-129 Stockpiles. https://documents.pub/document/stockpiles-intigobar-stockpiles-by-george-hsimmons-jr-technical-paper.html?page=1
124 Habert, G., Billard, C., Rossi, P., Chen, C., Roussel, N., 2010. Cement production technology improvement compared to factor 4
objectives. Cem. Concr. Res. 40, 820e826.
125https://www.eda.admin.ch/deza/en/home/projekte/projekte.html/content/dezaprojects/SDC/en/2013/7F08527/phase1
126 G. Asadollahfardi, A. Katebi, P. Taherian & A. Panahandeh (2019):
Environmental life cycle assessment of concrete with different mixed designs, International Journalof Construction Management, DOI: 10.1080/15623599.2019.1579015
127 Hossain, M. U., Dong, Y., & Ng, S. T. (2021). Influence of supplementary cementitious materials in sustainability performance of concrete
industry: A case study in Hong Kong. Case Studies in Construction Materials, 15, e00659. doi:10.1016/j.cscm.2021.e00659
128 Readily Implementable Strategies for Reducing Embodied Environmental Impacts of Concrete Pavements in the United States - Milena
Rangelov, Heather Dylla, Brian Dobling, Jagan Gudimettla, Nadarajah Sivaneswaran, Michael Praul (2022) Transportation Research Record,
2676(9), 436–450. https://doi.org/10.1177/03611981221086934

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decarbonising strategies outlined in the literature, they analysed data associated with paving
concrete mixtures from 27 projects across the United States between 2011 and 2019. The
opportunities for embodied carbon reduction were identified for the analysed dataset. The
study concluded that use of supplementary cementitious materials is beneficial but is alreadyquite common in practice. Thus, for further reduction it is essential to avoid mixture
overdesign and lower the cement content in concrete paving mixes. The study also highlighted
the need for appropriate specifications and consistent environmental reporting in
decarbonising concrete road construction.
Concrete waste from demolition can be used in the construction of roads, for building
concrete structures or in mortar production, along with other applications129, thereby
reducing CO2 emissions and reducing waste going to landfill. Braga et al.129 carried out a cradle
to grave life cycle assessment to compare concrete using virgin materials and recycled
aggregates. Using recycled concrete has potential to reduce environmental impacts and costs,
attributed partly to the higher structural performance of using recycled concrete in the mix.
Although the design of concrete roads and structures follow different design procedures, thecomposing material is essentially the same and the use of recycled aggregate is also applicablein rigid pavement construction130. However, as with other uses of secondary materials, theimpacts of processing and transporting the recovered material needs to be considered.
Another option is to reduce overall concrete volume. A study by Habert et al.131 examined theenvironmental impact of using a high-performance concrete over traditional concrete mixes
for bridge construction. Life cycle assessment was carried out to determine if a high strength
concrete mix with a higher cement content and associated higher embodied carbon was moreenvironmentally friendly considering the life cycle of the concrete structure. Using a highperformance concrete allows for a lower quantity of concrete to be used, which on average
can lead to a net decrease in CO2 emissions. The reduced porosity of high strength concretealso slows down the time of corrosion initiation of reinforcing steel, reducing the maintenancerequirements and potentially increasing the lifespan of the structure.
Rehabilitation of the Log Čezsoški bridge in Slovenia took place in 2009, with the use of a novel
Eco-Ultra-Fibre Performance Fibre Reinforced Concrete (ECO-UHPFRC)132. It is a single lane,
65m long, 3 span bridge. The rehabilitation involved the removal of the asphalt pavement,waterproofing membrane and 3 cm of mortar, and the addition of a continuous overlay of
ECO-UHPFRC. A life cycle assessment was carried out to examine the environmental

129 Braga, A.M., Silvestre, J.D., de Brito, J., Compared environmental and economic impact from cradle to gate of concrete with natural andrecycled coarse aggregates, Journal of Cleaner Production, 162, 2017, 529-543, doi.org/10.1016/j.jclepro.2017.06.057.
130 De Brito, J., Agrela, F., & Silva, R. V. (2019). Legal regulations of recycled aggregate concrete in buildings and roads. New Trends in EcoEfficient and Recycled Concrete, 509–526. doi:10.1016/b978-0-08-102480-5.00018-x
131 Habert, G., Arribe, D., Dehove, T., Espinasse, L., Le Roy, R., Reducing environmental impact by increasing the strength of concrete:quantification of the improvement to concrete bridges, Journal of Cleaner Production, Volume 35, November 2012, Pages 250-262.
132 Habert, G., Denarié, E., Šajna, A., Rossi, P., Lowering the global warming impact of bridge rehabilitations by using Ultra High
Performance Fibre Reinforced Concretes, Cement and Concrete Composites, Volume 38, April 2013, Pages 1-11.

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evaluation of possible rehabilitation strategies. The study compared the novel ECO-UHPFRC
application with a more traditional rehabilitation system using conventional concrete and awaterproofing membrane. It was concluded that CO2 impacts using ECO-EHPFRC wereapproximately 60% of the traditional concrete solution considering a 60-year life cycle. As acomparison, it was demonstrated that the CO2 impact of the traditional UHPFRC system was
73% of the conventional system of concrete and waterproofing membrane. The results areillustrated in Figure 12.

Global Warming Potential (tCO2)

80
70
60
50
40
30
20
10
0
Concrete/WPM

UHPFRCECO-UHPFRC

Figure 12. Effect of potential rehabilitation strategies on CO2 emissions (reproduced from132)

3.6

LOW ROLLING RESISTANCE PAVEMENTS

Careful construction of the pavement can reduce rolling resistance for vehicles using the road.
As seen in Figure 4, this currently represents the largest component of overall CO2 emissions.
Most literature agrees that pavement surface texture and roughness contribute to rolling
resistance and, hence, to vehicle fuel use. A selection of papers is reviewed by Ishigaki et al.,
who went on to construct two sections of Low Rolling Resistance Asphalt Pavement (LRRAP)
in Japan133.
Compared with a conventional porous asphalt, the LRRAP led to a reduction of 10-15% inrolling resistance and 2-4% reduction in the CO2 emissions of a test vehicle traversing thepavements. The two types of LRRAP were constructed with smaller aggregate than the porous
asphalt (2/5 grading rather than 5/13) and achieved both a smoother pavement(approximately 0.9 mm/m IRI compared with 1.12 mm/m) and lower texture (approximately
0.7 mm MPD (mean profile depth) compared with 1.6 mm). A conventional dense gradedasphalt was also constructed. This had relatively large aggregate size (0/13 grading), low

133 Ishigaki. T., Shirai, Y., Kawakami, A., Kubo, K., Low rolling resistance asphalt pavements for traffic energy saving and CO2 emission

reduction. 25th World Road Congress, Seoul 2015. https://proceedings-seoul2015.piarc.org/ressources/files/4/IP0680-Ishigaki-E.pdf

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texture (0.4 mm MPD) and a relatively rough surface (1.25 mm/m IRI). The performance of
this material was also considerably better than the porous asphalt although not quite as goodas the LRRAP – this suggests both texture and smoothness are important.
There are differences in the distribution of contact pressures between the tyre and thepavement surface for these materials (Figure 13) – the higher texture of the porous asphalt isapparent in the larger green areas of higher pressure, where the tyre is likely to be deformed
more strongly. Mukherjee134 notes that energy losses from the repeated deformation andrecovery of the tyre as it rolls are the main causes of rolling resistance, and that both surface
characteristics and structural characteristics of the road pavement contribute to this. The
values of rolling resistance coefficient (CRR) make clear the improvement in rolling resistancefor concrete and asphalt pavements (CRR of 0.013) compared with rolled gravel (0.02) andunpaved roads (0.5).

Figure 13. Contact pressures between the tyre and pavement surfaces from Ishigaki et al.133

134 Mukherjee. D., Effect of pavement conditions on rolling resistance. American Journal of Engineering Research 2014, vol 3, issue 7, p 141

CARBON NEUTRALITY OF THE ROAD SECTOR

A smaller contribution to the rolling resistance comesfrom the pavement structure. This was investigated byLengren135, who used a falling weight deflectometer toinvestigate the deformation response of different
pavement types. Lengren estimated that a rigid pavement
would contribute between 2 and 6 times less to rolling
resistance than a flexible pavement, but this wasdependent on the type of construction and the stiffnessof the surrounding soil. The temperature was alsosignificant, and, in winter conditions, there is reported tobe little difference between flexible and rigid
construction. It is noted that, although use of lime andcement stabilization has a high carbon footprint, when
designing the pavement this should be balanced against
the reduction in traffic induced emissions due to thestiffer pavement structure.

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Estimates of road user
CO2 savings associatedwith construction ofsmooth,stiff
pavements, comparedwithconventional
construction (per 1 km
of high traffic, 4-lanecarriageway during a
15-year life)

Lower estimate – 6,000
tonnesUpperestimate–
The 2-4% fuel saving found in the Japanese study is similar
12,000 tonnes
to that quoted by other sources136. In practice, the saving
will depend on the number of vehicles using the road andon their underlying fuel efficiency. To provide anapproximate indication of the scale of CO2 reduction possible from pavements that are stiff,even and negatively textured, it was calculated that for a road carrying high traffic (25,000
vehicles / lane / day) with 15% trucks, a 2-4% fuel saving would correspond to a saving of 100200 tonnes CO2 / lane km /year. Over a 15-year life, this would translate to saving 1500 – 3000
tonnes CO2 / lane km. For lower traffic levels, the saving will be correspondingly smaller, andthe potential saving will also reduce as engines become more fuel efficient or less carbon
intensive. This analysis assumed typical current emissions factors 252.5 gCO2/km137 and 2,022
gCO2/km for trucks138, assuming a 20 t load.
The MIT sustainability hub quantified excess fuel consumption associated with road stiffness
and roughness, displaying the results as a strip map139. Their assessment was that proper
maintenance to a small proportion of Virginia’s interstate system (65 lane miles out of 5,000
lane miles total) would reduce the CO2 emissions of the network by 10%.
3.7

DECARBONISATION OF CONSTRUCTION PLANT AND CONSTRUCTION OPERATIONS

135 Lenngren, C. A., Different pavement types and rolling resistance, 2014 International concrete sustainability conference, Boston
136 https://eapa.org/road-pavement-industries-highlight-huge-co2-savings-offered-by-maintaining-and-upgrading-road-view
137 https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle#driving
138 https://business.edf.org/insights/green-freight-math-how-to-calculate-emissions-for-a-truck-move/
139 Sustainable Pavements. MIT Concrete Sustainability Hub Factsheet (August 2018).

https://cshub.mit.edu/sites/default/files/documents/factsheet-pavements-UpdatedAug2018_FINAL.pdf

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It has been estimated140 that the typical energy consumption breakdown of a road
construction project is 75% material production, 20% transportation and 5% construction
itself. Whilst the exact energy consumption will vary with factors such as material used, typeof construction and transport distances, construction plant energy consumption is a small, but
not insignificant, contributor to road carbon energy emissions. This is not surprising given thesize of the machines involved and the weight of the materials they carry or move. A range offuel consumption of typical construction and maintenance machines is presented in Table 4,
below.
Table 4. Typical diesel use from construction plant141

Litres per hour Mid-Range
diesel use
FuelConsumption per hour (l)8-hourshift
fueluse (l)

5-day
work
week
fuel use(l)50-week
work
year fueluse (l)AnnualCO2emissions(kg)
at
2.4kg/lAnnualCO2emissions(tonnes)

Bulldozers: 13 – 18.95
25

151.6

758

37,9009,096091

Backhoes: 5.7 – 7.58
9.5

60.64

303.2

15,16036,38436

Small Trencher: 3.79
3.8

30.32

151.6

7,580

18,19218

Large Trencher: 39.795
34 – 45318.36 1,591.8

79,590191,016191

Grader: 38 – 45

41.69

333.52 1,667.6

83,380200,112200

Scraper: 64 – 72

68.22

545.76 2,728.8

13,6440

327,456

327

Excavator: 38 – 45.48
53363.84 1,819.2

90,960218,304

218

All the machines listed in the table above produce tens of tonnes of CO2 per year andpotentially in the hundreds of tonnes per year. Consideration of the sheer number of thesemachines worldwide demonstrates the high potential to reduce carbon emissions if diesel
consumption could be replaced with cleaner alternatives. Potential options are presented

140 https://pavementinteractive.org/energy-and-road-construction-whats-the-mileage-of-roadway/
141 https://cpower.com/2021/11/16/types-of-gas-for-your-rental-construction-vehicle/

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below. The Criminal Intelligence Agency (CIA)142 report that there are around 12.7 million
kilometres of paved roads worldwide. The potential maintenance carbon is estimated asfollows.
Table 5. Estimate of worldwide, annual carbon emissions associated with use of plant

Data and assumptions

Calculations

Length of paved roads worldwide

12,717,850 km

Lane km – conservative estimate of each road being 2 25,435,700 km
lanes
Annual length maintained – assume maintenance every 2,543,570 km
10 years (i.e. 10% annual)
Energy associated with maintenance – assume 1TJ per 2,543,570 TJ
lane km
Energy associated with use of plant – assume 5% of 127,179 TJ
energy from plant
Estimate total fuel usage – 1 litre diesel = 38MJ

3.35 billion
consumed

litresdieselEstimate of total carbon emissions associated with use 8 billion kg / 8 million tonnesof plant – 2.4 kg CO2 emitted per litre diesel burnt
Reduction of demand
The first step before looking to replace a fuel will be to reduce existing fuel / energy use.
Numerous sites143,144 offer general advice on ways to maximise fuel efficiency of vehicles,
including manufacturers of the equipment 145. Some of the key themes are as follows:•••

Maintain the machine to keep it in good condition, including checking oil and liquid levels, tyrepressures where appropriate, air filters
Minimise idling and look for machines with start/stop features
Use trained operators as they will operate the machinery more efficiently. Some machines
have telematics that can improve operator training. Stein et al146 reference a study where
efficiency varied by 40% between operators undertaking the same task

142 https://www.cia.gov/the-world-factbook/field/roadways/country-comparison
143 https://www.construction-europe.com/news/6-ways-to-increase-fuel-efficiency-for-heavy-construction-equipment/8013326.article
144 https://www.equipmentworld.com/equipment/article/15292688/reducing-diesel-fuel-consumption-in-construction-equipment
145 https://volvoceblog.com/tips-to-cut-heavy-equipment-fuel-consumption/
146 https://www.researchgate.net/publication/260058937_Fuel_efficiency_in_construction_equipment_-_optimize_the_machine_as_one_system

CARBON NEUTRALITY OF THE ROAD SECTOR

•
•
•
•

Where machines have data collection, this can be used to provide early warning of inefficiency
and enable preventative/early maintenance or repair to be undertaken
Using the right machine for the job, so called ‘right-sizing’ improves productivity but also fuelby ensuring machines are paired together
Some machines have eco pedals that push back in response to excessive accelerator use.
For asphalt compaction there are programmes to maximise compaction requirements without
excessive passes

Stein et al point out that there are three areas for
reduction of carbon on construction sites:•••

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With job site optimisation

Job site optimisation – refers to how the site isalone capable of enabling
established, using the correct sized plant for the job,fuel savings of 30%, thismaximising turning circle improvements for smoothcombined with machinerunning and minimising queuing and waiting time.
optimisation and machine
Whilst it is highly site dependent, they report that fuelsavings of up to 30% have been identified.
control
toincrease
Machine use optimisation – this covers how theefficiency,
could
machine itself is used and the reported savings frompotentially produce fuelhaving trained operators, using only the requiredsavings of 50% on someforce for the job. The savings (or losses fromplant operations.
inexperienced operators) could be improved frommachine control (see below).
Machine optimisation covers the mechanics of the machine use including hydraulics anddrivetrain. Stein et al report that peak power demand is in the bucket filling phase where
hydraulics and drivetrain are both consuming up to the maximum engine power, accounting
for around 40% of fuel consumption. This also gives a large potential to minimise losses in thephase through technologies such as charging energy storage in time of limited use, to use thepower in times of need and attempting to optimise the balance between the power used forthe engine, hydraulics and propulsion.

Connected and Automated Plant (CAP) / Machine Control
As with road vehicles, there has been research undertaken on connected and autonomous
plant. For simple, repetitive tasks such as trench digging and loading vehicles, autonomous
plant has been developed to undertake them remotely, with significant operator savings andfuel and equipment saving by undertaking the task perfectly and efficiently each time. This
frees the skilled operator to undertake tasks that require the human dexterity that is beyond
the capability of a robot.
Machines in the construction industry 147,148,149 range from machine assistance to examples offull autonomy. Fully autonomous vehicles have been developed for use in controlled

147 https://cacm.acm.org/news/224172-autonomous-construction-vehicles-are-building-the-future/fulltext
148 https://future-markets-magazine.com/en/markets-technology-en/autonomous-construction-machines/
149 https://www.equipmentworld.com/tag/autonomous-construction-equipment/

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environments such as open cast mines, where they autonomously collect material from themine floor and bring it to the processing plant at the top.
The CEDR STAPLE (SiTe Automation for Practical Learning) project provides details of various
research and development in the area. In the road construction and maintenance sector,
applications are limited so far, although an area of research is in compaction equipment, as
the correct level of compaction with an even number of passes has a strong influence on thesubsequent road quality and longevity. Longer lived pavements with fewer maintenanceinterventions has a clear carbon saving.
Research in this area was reported in the STAPLE deliverables, detailing that BOMAG150 has
undertaken research to develop a fully autonomous tandem roller, containing GPS, Lidar andadvanced position sensors, enabling it to be used fully autonomously in defined work areas.
Machine assist, or semi-autonomous plant is likely to be more relevant and is already in use
in many machines. Trimble report151 that over 100,000 earth moving (dozer) vehicles werefitted with machine control worldwide. Whilst such plant still needs an operator, it wasreported that machine assist enables experienced operators to run 41% faster and 75% moreaccurately, whilst new operators will run 28% faster and 100% more accurately. Whilst the
motivation is improved productivity, quality and safety, their increased efficient also delivers
carbon savings.
For example, excavator depths can be set which not only avoid hitting know undergroundutilities, and achieve perfect grading, but prevent over digging, which wastes fuel. Given thatbucket filling accounts for 40% of fuel consumption, significant carbon savings can be made,particularly for novice operators.
Electric Power
Many companies are introducing ranges of fully electric construction plant, which offer
reduced noise as well as zero emissions. At this stage, this is limited to smaller, less powerfulmachines. For example, JCB offers a range152 including 500 kg and 1 tonne site dumpers, mini
excavators, forklifts and access platforms, plus a range of charging solutions, with a stated fulltypical day use on a single charge. Volvo153 are another major equipment supplier offering
battery powered mini excavators and wheeled loaders and have announced 154 that they willstop development of diesel engine compact wheel loaders and compact excavators.
There have been examples of large battery powered equipment, including an all-electric 26
tonne excavator with a 300kWh battery pack from Caterpillar155, with the batteries alone

150 https://www.bomag.com/ww-en/press/news-videos/future-study-fully-autonomous-tandem-roller/
151 STAPLE (2020) Practical learnings from test sites and impact assessments, Deliverable No 4.1 & 4.2
152 https://www.jcb.com/en-gb/campaigns/etech-range
153 https://www.volvoce.com/global/en/our-offer/emobility/
154 https://electrek.co/2019/01/17/construction-equipment-electric-volvo-ce/
155 https://electrek.co/2019/01/29/caterpillar-electric-excavator-giant-battery-pack/CARBON NEUTRALITY OF THE ROAD SECTOR

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weighing 3.4 tonnes giving 5 – 7 hours of operation. Even larger, is a prototype 110 tonne
converted Komatsu dumper with a 700kWh battery pack156, working in a mine in Switzerland.
An advantage of this operation is that whilst diesel trucks use fuel even on their way down amine, the prototype vehicle can use regenerative braking to recoup 40 kWh on each trip down
the quarry, totalling 800 kWh per day for the 20 journeys it makes. This can potentially offer
massive savings given that a typical dumper truck of this type uses between 50,000 and
100,000 litres of diesel per year – taking the midpoint of the range equates to around theaverage fuel use per year of 37 cars in the USA and 110 cars in the European Union based on
average annual milage and emissions157. Should this trial prove success, they may retrofit
further vehicles of this type.
In another example158, ABB and Hitachi have joined forces to develop a catenary powered
electric dump truck.
Alternatives to diesel
Whilst there are examples of very large electric vehicles in development in quarries, the fixednature of the sites does make them particularly suitable for an electric transition. The vehicles
can be charged overnight or, with catenary charging can be charged for most of the routefrom the quarry floor, plus the potential for regenerative braking on downhill runs. The same
is not necessarily the case for the more mobile equipment typically used in highway
construction and maintenance.
As detailed above, many smaller machines are suitable for battery power, but for larger plant,
due to the weight of batteries and charging times, other alternatives are being suggested,mainly biodiesel and hydrogen in various forms.
Biofuel has an obvious advantage in that it can be used as a direct replacement for existingmachines, but there are concerns around land use, if biofuel crops are displacing land suitablefor growing food. There are concerns around the relatively low efficiencies of some crops used
for bioethanol, for example it is reported that ethanol from corn produces 30% more energy
than that used to grow it159, which is significantly higher than sugar and soy-based ethanol.
The other concern is realistically how much could be grown. The potential for algae or kelp
produced fuels shows promise and could be undertaken so as to not compete with agriculturalland but requires development.
Many plant manufacturers see hydrogen as a solution for their machinery, with JCB seeing
this as the solution for machinery over 5 tonnes. They have demonstrated a 20-tonne
156 https://electrek.co/2017/09/17/electric-dumper-truck-worlds-largest-ev-battery-pack/157 Average EU car efficiency = 6 litres per 100 km (https://www.iea.org/articles/fuel-economy-in-the-european-union) and average annual

km 11,313 (https://www.odyssee-mure.eu/publications/efficiency-by-sector/transport/distance-travelled-by-car.htm)l = 678.78 litres percar, per year. Average USA car fuel efficiency = 9.3 litres per 100km (https://www.epa.gov/automotive-trends/highlights-automotivetrends-report) and 21,687 annual km per year = 2,017 litres per car per year (https://www.fhwa.dot.gov/ohim/onh00/bar8.htm)
158 https://www.australianmining.com.au/news/abb-hitachi-to-design-electric-dump-truck/
159 https://biofuels-news.com/news/future-trends-in-biofuel/CARBON NEUTRALITY OF THE ROAD SECTOR

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excavator using a hydrogen fuel cell but consider that fuel cell powertrains are not yet
sufficiently robust for the construction industry. Instead, they favour burning hydrogen in
combustion engines and have demonstrated its use in a 4.8 litre backhoe excavator. They state
the engine will cost the same as standard engines and can be retrofitted to existing vehicles,with hydrogen supplied on building sites in mobile tankers as diesel is now. 160
Burning hydrogen in this way utilises much of the same diesel engine technology
infrastructure, requiring only modification of the internal combustion engine to burnhydrogen instead of diesel. Burning hydrogen does still produce nitrous oxides although thesecan be minimised.
Fuel cells are more efficient than burning hydrogen and do not produce NOx, with heat andwater vapour being the only tailpipe emissions. In March 2021, SANY announced it hadlaunched a hydrogen fuel cell dump truck and mixer truck161. Meanwhile, Volvo has started
testing the world’s first prototype of a hydrogen fuel cell articulated hauler, having a range ofbattery electric solutions already. Volve CE has a Science Based Targets initiative (SBTi) with acommitment to net-zero value chain greenhouse gas emissions by 2040 and driving industry
transformation towards carbon neutrality162. With hydrogen infrastructure remaining an
issue, Volvo worked with Shell to provide the fuelling infrastructure at its test site. Both Volvoand Shell are founder members of H2Accelerate, a collaboration of companies working todevelop conditions to roll out hydrogen trucks in Europe.
Keltbray has agreed a deal with AFC Energy to install hydrogen fuel cells on one of its
construction sites, expected in the second quarter of 2022163. Keltbray has a company targetof net zero carbon by 2040.
An issue with batteries and fuel cells is the low volume of machines, but there is likely to be atransition over the next 5 to 10 years as they become operationally and economically viable.
A remaining challenge is around the fuelling infrastructure itself in terms of storage anddistribution, with the final challenge being the cost of hydrogen and the production of greenhydrogen, as most hydrogen produced today is a by-product of the petroleum industry.
Road maintenance alone may account for 8 million tonnes of CO2. A
significant proportion could be saved through job site and machine
optimisation. The remaining energy requirements could be met
through a combination of clean electric or green hydrogen.
Many NRAs do not own their own fleet of construction vehicles, with construction andmaintenance being undertaken by contractors. Contractors have incentives to invest in new160

https://www.autocar.co.uk/car-news/industry-news-manufacturing/under-skin-how-hydrogen-could-fuel-future-plant-machinery

161 https://www.forconstructionpros.com/equipment/earthmoving/article/21940605/large-machinery-oems-explore-hydrogen-future162

https://www.worldhighways.com/wh2/news/volvo-ce-starts-testing-worlds-first-prototype-hydrogen-articulated-hauler
https://www.constructionnews.co.uk/sustainability/keltbray-construction-site-to-be-powered-by-hydrogen-fuel-cell-in-uk-first-15-032022/
163

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machinery for commercial reasons, for example, machine assist and semi or fully autonomous
operation, and for their own corporate targets around carbon reduction for alternative fueluse. Road owners can play a role in accelerating the shift towards low carbon construction
fleets through contract conditions, carbon targets and incentives.
3.7.1

Solar / hydrogen lighting replacing diesel generators

Diesel generators have typically been used to provide site lighting on road works and otherconstruction sites. In recent years, there has been a range of solar alternatives becoming
available for sale or hire. Not only do these prove to be a zero-carbon source of lighting, butthey avoid the requirement for refuelling with diesel, whilst also having no emissions andlower or no noise. UK company Prolectric164 has a lighting tower which has been used by Tier
1 contractors on rail and highways site and claims to work even in winter conditions with 16
hours of darkness.
In situations where this might not be suitable, there are solar hybrid options 165 with a diesel
back up.
The use of hydrogen fuel cell powered lighting and site power has been trialled on London’s
Crossrail project166 as well as other locations as an alternative to diesel power. It can beparticularly useful in enclosed locations due to zero emissions.
Development of hydrogen generators for site work is likely to increase due to demand fromother sectors. For example, they are popular with film and tv crews due to their silent
operation, and for zero emissions music festivals. Whilst the immediate relevance to the road
sector might not be obvious, the fact that there are other sectors who use hydrogengenerators reveals that a market exists, which should bring costs down and see themechanisms for hydrogen delivery improve.
Diesel Generator Contribution to Carbon Emissions
Estimating the contribution of diesel generators to carbon emissions is challenging due to thelevel of detail available on the type of generators and the location of their use. Many
generators are used for direct electricity generation, for back up electricity production and tobalance electricity produced by electricity grids. For those used on construction sites, there isno breakdown available as to whether they are used for road applications, or for otherpurposes, for example rail works or general construction activities, such as house building
sites.

164 https://www.prolectric.co.uk/lighting/solar-lighting-towers/prolight-solar-lighting-tower/
165 https://www.sunbeltrentals.co.uk/lighting/tower-lights/9m-led-tower-light---solar-hybrid-1784/
166 https://www.bechtel.com/projects/crossrail-london/CARBON NEUTRALITY OF THE ROAD SECTOR

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The use of diesel generation is likely to be significant, with one article167 reporting that 15% ofLondon’s diesel emissions were due to construction site generators. BAM report168 that a
60kVA generator for a small to medium sized construction site compound would use around
1,000 litres of diesel per week. Smaller, mobile 40kVA generators consume around 9 litres offuel per hour169. Lighting towers with inbuilt diesel generators are also frequently used in road
construction and operation for night-time working, lighting of contraflow entrances and exits
and for site compounds. These tend to be smaller units, using between 0.4 to 2 litres of fuelper hour170. The exact number of generators and lighting towers in operation is difficult toestimate, in particular for those used for road operation, not least as they are used for many
applications, such as buildings construction, rail, tv and films, festivals etc.
3.7.2

Potential Carbon Savings from Alternative Power Lighting Towers and Generators

There were 105,000 lighting
towers sold in 2019171, of which
Estimates of CO2 savings possible for replacing
55.4% of new models are diesel,
diesel lighting towers with solar or green hydrogenwith the remainder being solar or
alternatives
hydrogen. It is assumed that this
proportion of solar and hydrogen
1,000 units – 5,000 tonnes
models sold will increase over
10,000 units – 50,000 tonnes
time as the technology becomes
more widely adopted. It is also
100,000 units – 500,000 tonnes
likely that most of the older
models in use will be diesel operation.
Based on a lower end estimate172, each diesel unit burns 0.7 litres per hour. As these units aremobile, and potentially rented, an estimate might be for use 300 days per year at an averageof 10 hours per day. Using these assumptions, a unit would burn 7 litres of fuel per day and2,100 litres per year. As each litre of diesel burned173 emits 2.4 kg CO2, this equates to 5,040
kg of CO2 (or 5 tonnes) per unit, per year.
No information was found on the overall number of lighting towers in use, or the proportionof the units used in road construction and maintenance. As such it is not possible to provide
an estimate of the potential savings that could be made without making many assumptions,

167 https://www.cbi.org.uk/articles/cleaning-up-construction-the-fuel-cell-alternative-to-diesel/
168 https://www.bam.com/en/sustainability/innovations/alternative-power-sources-at-construction-sites
169 https://www.ablesales.com.au/blog/diesel-generator-fuel-consumption-chart-in-litres.html
170 chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.jarvieplant.co.uk/assets/000/000/264/GAWL-

11X_VB_9__Eco_Towerlight_Spec_Sheet_original.pdf?1618311941
171 https://cpnonline.co.uk/news/diesel-light-towers-accounted-5-10-units-sold-2018/172 chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.johnfhuntpower.co.uk/wp-content/uploads/2020/04/TL90-LEDLighting-Tower-1.pdf
173 https://www.researchgate.net/publication/235458666_Estimation_of_Carbon_Footprints_from_Diesel_Generator_EmissionsCARBON NEUTRALITY OF THE ROAD SECTOR

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however a range of savings based on replacing diesel generators with solar or green hydrogen
could be made as shown above.
Diesel Generators
There was no available data for the numbers of diesel generators in use for the road sector,
only the permanent generators used for general electricity production or to back up / balancenational grid (82.6 million174). It is likely that the number of diesel generators far exceeds thenumber of lighting towers, as they are used for multiple applications, potentially at any timeof the day. The range of uses and the size of generator used accordingly can vary widely, fromsmall 2 – 3 kVA petrol units designed to run a single small tool, to large generators of over
200kVA to run site compounds.
As an example, a mid-range 40 kVA generator operating at 75% load, uses 9 litres per hour175,
over 10 times that of a lighting tower. Assuming the generator would operate an 8-hour shift
per day and 300 days per year, would use 21,600 litres of fuel per year (9 x 8 = 72 litres perday, 72 x 300 = 21,600). At 2.4 kg of CO2 emitted per litre of diesel, 51,840 kg or 5.18 tonnesof CO2 would be emitted, per unit, per year.
The potential savings from moving away from diesel generators to solar or cleanhydrogen alternatives could be in the order of millions of tonnes per year. NRAs
should ask their supply chain about the number and type of generators they use
and set a roadmap for solar / hydrogen adoption.
Given the range in sizes and specifications, it is very difficult to make a realistic estimate ofpotential savings, not least as the infrastructure to replace the larger generators withhydrogen is not in place currently. Based on the example above, with a single unit emitting 5
tonnes of CO2 per year and there being more generators in use, a range of 50,000 to 5 million
tonnes of CO2 per year, based on 10,000 to 1 million generators worldwide replaced withgreen hydrogen respectively.
The numbers above indicate that for lighting towers and generators, the CO2 savings fromswitching from diesel generators to solar or green hydrogen alternatives could be in the orderof millions of tonnes per year. These numbers make many assumptions and the exact quantityof potential savings, will be based on numerous factors including the exact number of units,
the number of hours they are used and the breakdown of the power consumption of the units
in operation. For diesel generators specifically, there is a large variation in the size of the units
and the amount of time they are used.

174 https://askwonder.com/research/explore-topic-number-diesel-generators-u-s-globally-

npadnargx#:~:text=Assuming%20that%20this%20proportion%20also,70%25%20of%20118%20million).
175 https://www.ablesales.com.au/blog/diesel-generator-fuel-consumption-chart-in-litres.html

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The exact savings available, will not only be affected by the factors outlined above, but on the
choice of alternative operations. Solar power may be a viable option for lighting towers andsmall generators, whereas for larger generators, it is likely that whilst solar could provide somepower in a hybrid operation, an alternative power source will be required. Hydrogengenerators could be a viable alternative, and, as with solar, offer the benefits of silent
operation and local air quality improvement. How the hydrogen is generated, will have an
impact on the potential carbon savings, with green hydrogen powered by renewable energy
offering 100% of the potential savings. Hydrogen produced by other means will have theenergy intensity of the electricity grid from which it is produced.
For example, the average carbon intensity of electricity per kWh (as measured in grams CO₂
per kilowatt-hour) is 425 g worldwide176, 482 g for upper middle and high income countries,
413 g for lower middle income countries and 313 g for low income countries, but there arelarge differences, for example, high income Norway having a carbon intensity of only 25
g/kWh due to the large use of hydropower. The proportion of energy generation sourced byrenewable sources will determine the potential carbon savings achievable, as outlined in
Figure 14. For example, Brazil, Canada, France, Sweden and Norway all produce electricity
from 80% or more from nuclear or renewables, whereas Japan, Australia, India and South
Africa each use over 70% of fossil fuel sources for their electricity production.

176 https://ourworldindata.org/grapher/carbon-intensity-electricity

CARBON NEUTRALITY OF THE ROAD SECTOR

Figure 14. Sources of electricity production by country

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4 DECARBONISATION OF ROAD USER VEHICLES
There are approximately 1.45 billion177 vehicles in the world and whilst there are shifts incertain countries to promote increased active travel and public transport, it is likely that, as
the global population grows and many LMICs continue to grow economically, there will be
increased vehicle ownership in the future.
Figure 4 shows how vehicle energy use is far higher (around 18 times over its lifetime,depending on the road) than the energy used to construct the road. Currently, most vehicles
are powered by internal combustion engines, although electric vehicle adoption is increasing
and will continue to do so with upcoming bans on the sale of internal combustion engines forcars and vans in Europe and elsewhere.
Decarbonisation of vehicles can be split into 3 broad options: alternative fuels (mainly
biofuels), electrification and hydrogen. As biofuels are designed to replace some or all theexisting petrol and diesel used in existing combustion engines, these will be considered as astandalone section, with hydrogen and electrification considered across various vehicle
categories, as the size and required range of the vehicle will in part determine which fuels aremost suitable.
4.1

ALTERNATIVE FUELS / BIOFUELSIn Europe, most petrol sold on the forecourt contains 5% biofuel in the form of bioethanol,
denoted as E5 with many countries now moving to 10%, E10. It is reported178 that all new
vehicles and those put on the market since 2011 would be able to run on a blend of 20%
bioethanol. This would reduce greenhouse gas emissions by an equivalent 25.4Mt of carbon
dioxide in the 27 EC states plus the UK, which is around 8.2% of current emissions. Whilst the
UK has moved to E10, there is an obligation to also sell an E5 grade for those vehicles
incompatible with the higher blend.
The USA started to Introduce ethanol into gasoline in 2007 and in most areas of the country,
most retail gasoline in now 10% ethanol by volume.
The AA179 states that diesel with a blend of up to 7% biodiesel is safe to use with a 5% (B5)blend commonly sold.
Whilst biofuel blends can be used in vehicles with little or no modification, there are concerns
over the use of agricultural land to grow crops for fuel production, rather than food. Also, insome cases palm oil is used to produce biodiesel. Both these factors raise questions aroundthe overall sustainability of current biofuels. Further, the properties of biodiesel can be177

https://hedgescompany.com/blog/2021/06/how-many-cars-are-there-in-theworld/#:~:text=Two%20major%20countries%20are%20virtually,in%20the%20world%20in%202022
178 https://ec.europa.eu/research-and-innovation/en/horizon-magazine/why-raising-alcohol-content-europes-fuels-could-reduce-carbonemissions
179 https://www.theaa.com/driving-advice/fuels-environment/biofuels

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markedly different to standard oil depending on the composition. According to the AA,
rapeseed is liquid at 0oC, but soy is solid, which can affect cold weather operation.
Current biofuels tend to be manufactured from plant matter. Second generation or advanced
biofuels are manufactured from non-edible sources such as woody crops, wood chips andagricultural waste such as husks and stems. This is better from an agricultural standpoint as
the edible crop goes into the food chain, whilst the ‘waste’ goes to biofuel production. Several
demonstration facilities for this process have been built but it is not yet operational at anindustrial scale.
Third generation fuels are those characterised by being based on algal production180, which
offers many potential advantages in terms of yield and diversity of organisms enabling a wide
range of fuels to be developed. It is reported181 that algal biofuels can be less stable thanothers, but the main drawback is economic viability. Exxon Mobil invested $600 million USD
in research and development and concluded in 2013 that algal fuel would not be viable for atleast 25 years. It should be noted of course that we are now almost 10 years into that
timeframe, with technical and economic factors having moved on in that time.
There are also synthetic fuels, most of which are based on well-known and proven chemical
processes which involve processing of syngas, a mixture of carbon monoxide and hydrogen
into a liquid fuel. The syngas is usually derived from gasification of solid feedstocks such ascoal, shale tar, biomass or reforming natural gas182. Gas derived from anaerobic digestion
facilities can also be used for this process. Clearly fuel derived from anything other thanbiomass will not contribute to carbon neutrality and will likely be more carbon intensive thanusing current petrol and diesel.
Finally, another alternative being explored is efuels, which replicate the hydrocarbons inpetrol or diesel by using carbon from the air and hydrogen from water 183. The process istechnically feasible although it takes a lot of energy, albeit that this could be sourced byrenewables.
Porsche has invested $75 million USD into a Chilean start-up operating this process, working
with Siemens and Exxon Mobil184. The plant captures CO2 from the atmosphere and uses wind
power to electrolyse water into hydrogen and oxygen. The carbon and hydrogen are used tocreate methanol, which in turn is turned into longer hydrocarbons using Exxon Mobil’s
methanol to gasoline process. The plant is targeted to produce 130,000 litres by the end of2022 rising to 550 million litres by the end of 2026 at a cost of around $2 USD per litre. Whilst
process efficiencies will improve, the cost and production volume mean it’s unlikely that this180 https://academic.oup.com/af/article/3/2/6/4638639
181 https://biofuel.org.uk/third-generation-biofuels.html
182 https://www.sciencedirect.com/topics/engineering/synthetic-fuel
183 https://www.autoexpress.co.uk/tips-advice/356000/what-are-synthetic-fuels-efuels-explained
184 https://arstechnica.com/cars/2022/04/porsche-invests-75-million-in-chilean-synthetic-fuel-startup/CARBON NEUTRALITY OF THE ROAD SECTOR

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will replace the petrol and diesel used today, not to mention the timescale by which mostvehicles, particularly in HIC will be electric. Further, the tailpipe emissions and local air quality
issues remain. Porsche’s motivation towards development of efuels is twofold:••To keep the historic Porsche fleet globally moving
To be used for racing, with Formula 1 moving to 100% renewable fuel in the mid-2020s withefuel as an option185

Efuel could be one part of an overall solution for decarbonisation and have a niche applicationin powering classic cars and other historic vehicles.
4.2

CARS AND VANS

Electrification
Electric vehicles (EVs) have developed in recent years to a stage where all major car brands
either already have electric vehicles in their portfolio186 or will have in the next 2 or 3 years.
Whilst Tesla has always been 100% electric, other car brands have set dates for transition toan all-electric future; for example, Jaguar will be all electric by 2025, Volvo pledging to be
50:50 hybrid and full electric vehicles by 2025 and all electric by 2030, with many othercompanies setting a 2030 deadline187. This is no doubt being driven in part by the EC ban oninternal combustion engine vehicles by 2035, with many countries having earlier targets188,
for example 2025 in Norway and South Korea, 2026 in Belgium, 2027 in Austria and 2030 inother countries including Sweden, Denmark, Israel and India.
It has been reported189 that EV sales more than doubled to 6.6 million units in 2021,
representing around 9% of the global new car market and tripling their market share from2019.
Whilst limited range and ‘range anxiety’ was a real issue in early EVs, most now have a rangeof over 300 kilometres, with some having ranges of over 600 kilometres. Very few people drive
this sort of distance on a regular basis, with average annual km driven per year in Europe andthe USA equating to around 30 or 60 km per day respectively.
There is now a large range of electric vans available, with ranges from around 200 – 300 km.
As many vans operate on fixed routes, this range is adequate, whilst the vehicles can be
charged overnight. As part of its commitment to be carbon neutral by 2040, Amazon is
working with start-up Rivian to produce 100,000 vans190 in the USA, with the first ones being
delivered in 2021 and the process of installing charge points is underway. For the UK and

185

https://www.formula1.com/en/latest/article.pat-symonds-on-how-formula-1-are-creating-the-next-generation-of100.6XCGNQ3ExMhbhYy338Qgi2.html
186 https://www.driving.co.uk/news/new-cars/current-upcoming-pure-electric-car-guide-updated/
187 https://www.abc.net.au/news/2021-11-10/which-cars-going-all-electric-and-when/100529330
188 https://insideevs.com/news/534890/countries-states-gas-car-bans/
189 https://www.iea.org/commentaries/electric-cars-fend-off-supply-challenges-to-more-than-double-global-sales
190 https://www.driving.co.uk/news/business/amazons-rivian-delivery-vans-roll-l/CARBON NEUTRALITY OF THE ROAD SECTOR

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Europe, Amazon has ordered 1,800 vans from Mercedes Benz, with other companies withlarge fleets following suit. For example, UPS ordered 10,000 vehicles from Arrival in the UK191.
Given the direction of the major car manufacturers, battery electric power is likely to be thedominant vehicle type for cars and vans from 2030 onwards.
There remain some technical hurdles. More charge points, including fast chargers need to beinstalled to cope with the increase in EVs. There is a requirement for more battery recycling
facilities to reduce the requirement for extraction of virgin materials. There is currently also alack of trained technicians capable of maintaining EVs. The largest issue is likely to be the fuelmix that produces electricity to feed the grid which in turn powers the EVs. Energy sourced
from renewable power provides the greatest savings in terms of carbon reduction.
A final issue is the manufacture of the batteries themselves. The cost of lithium-ion batteries
has decreased dramatically and is predicted to drop further, meaning it will likely be thedominant battery source for the foreseeable future, but the question of available lithium andother metals remains. Generally, the opinion seems to be192,193 that there are sufficientmaterials, but that the quality of lithium will decrease and/or the cost to mine will increase.
There are some concerns194 that demand could outstrip supply in the short to medium term
given the long lead times in developing the factories and supply chains. This makes thedevelopment of recycling facilities for depleted EV batteries more important.
There have been initiatives exploring the feasibility of battery swapping as an alternative tocharging of batteries at a station, with Chinese company Nio opening 700 stations in 2021195.
It has also launched a battery as a service subscription196 service where users pay $142 for a
70 kW battery with six monthly swaps. Realistically, the business case for battery swapping nolonger exists. Whilst it was a promising idea in the early days of electric vehicles, with very low
ranges and little dedicated charging options, it no longer appears to be a sensible approach.
In fact, Tesla proposed this as an option for their vehicles, before coming down on the side of
rapid charging. Along with the fact that it would require standard batteries for all cars, modern
EVs have large ranges of several hundred kilometres and some fast chargers can charge avehicle in 20 minutes, with improvements on this likely to be developed. Other issues are thatthe battery swap stations are very expensive, and whilst they use robots to remove andreplace the battery, each station has a human operative.
Hydrogen Cars and Vans

191

https://www.vertumotors.com/news/amazon-orders-1800-mercedes-benz-electric-delivery-vans-for-uk-and-eu/

192 https://www.nature.com/articles/d41586-021-02222-1
193 https://medium.com/batterybits/is-there-enough-lithium-to-make-all-the-batteries-c3a522c01498
194 https://www.bloomberg.com/news/articles/2022-04-22/mr-lithiumalr-warns-there-s-not-enough-battery-metal-to-go-around#:~:text=Lithium'%20Warns%20There's%20Not%20Enough,the%20electric%20car%20production%20planned.
195 https://www.autotrader.co.uk/content/news/what-is-battery-swapping-and-is-it-a-good-idea
196 https://spectrum.ieee.org/ev-battery-swapping-how-is-this-a-good-idea

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Several years ago, hydrogen cars were seen as the future of transport, in large part due to theconcerns over electric vehicle battery range, performance and long charging times. Progresshas halted in that time, in large part due to lack of fuelling infrastructure and the productionof hydrogen largely being from fossil fuels.
Whilst many vehicle manufacturers developed hydrogen demonstration vehicles, particularlyin the early 2000’s197, only two production vehicles are currently available, the Toyota Mirai II
and the Hyundai Nexo, although BMW, Land Rover and Vauxhall (Opel) plan models in thenext 5 years198.
Even with future models planned, there were only 26,000 hydrogen vehicles registeredworldwide in 2020199, concentrated in Korea, California and Japan, compared to 3 million EV
sales in the same year. Toyota remains the only car manufacturer committed to promotinghydrogen fuel cells as a solution for cars, although it is also looking to develop the technology
for heavy vehicles200. Many commentators think that Toyota is making a mistake in pursuingthis ambition201 due to the expense and complexity of fuel cells, whilst other motor
manufacturers think that battery power is more favourable. The CEO of Volkswagen tweetedin 2021 that “Green hydrogen is needed for steel, chemical, aero … and should not end up in
cars. Far too expensive, inefficient, slow and difficult to roll out and transport.”

197 https://en.wikipedia.org/wiki/List_of_fuel_cell_vehicles
198 https://www.autoexpress.co.uk/electric-cars/93180/hydrogen-fuel-cells-do-hydrogen-cars-have-future
199 https://www.wired.co.uk/article/future-buses-hydrogen-electric#:~:text=Registrations%20of%20hydrogen%20cars%20remain,largely%20California)%2C%20and%20Japan.
200 https://www.toyota-europe.com/world-of-toyota/electrified/fuel-cell/
201 https://medium.com/the-future-is-electric/did-toyota-make-a-mistake-with-hydrogen-and-the-mirai-952a179ee898

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Figure 15. Hydrogen filling station at National Renewable Energy Laboratory, Colorado©Maple Consulting

A continuing problem for hydrogen cars is the lack of infrastructure, with battery charging
much easier due to the prevalence of the electric grid. There are currently very few hydrogen
refuelling stations (e.g. 11 in the UK) and this needs to be increased significantly for hydrogento be a viable fuel. This is unlikely to be feasible for passenger vehicles but could be achievableas part of larger transition to the hydrogen economy, for example for larger road vehicles, rail,
aviation, shipping and power for heating in buildings.
4.3

BUSES

Electric BusesElectric buses are not new. Many cities around the world had trolleybus services, where thebuses are powered by overhead wires like a tram. Whilst 500 trolleybus services have been
lost202 (many were converted to standard bus fleets due to the improved flexibility without
wires), there are 300 cities where they remain.

202 https://en.wikipedia.org/wiki/Trolleybus

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Battery electric buses exist in many cities in the world, dominated by Chinese cities.
Bloomberg reported203 that at the end of 2020 there were 598,000 electric buses worldwide,of which 585,000 were in China. It was also predicted that there would be 1.7 million in
operation in 2030. Many cities will be switching
to e-buses as they seek to meet their carbon
The 600,000 electric buses operating
reduction targets and to improve urban airin China could reduce carbon
quality – buses are relatively heavy, have a highemissions by over 45 million tonnes
mileage and operate under stop/start driving
per year if they were powered byconditions. Given the number of e-buses inrenewable energy
operation now, the vehicle technology is clearlymature, with buses well suited to electric operation as they run on fixed routes and can chargeovernight at the depot, or in some cases at points along the route. From an environmental
point of view, e-buses can represent a good option for decarbonisation, as the same article
states that every 1,000 e-buses on the road displace 500 barrels of diesel per day (1 barrel =42 US Gallons or 159 litres). Based on 598,000 e-buses, operating 365 days per year, equates
to 17,352,465,000 litres of diesel. According to a carbon calculator204, this equates to45,463,458 tonnes of CO2. It is noted that not all this carbon will be removed unless the bus ispowered by renewable energy.
For coaches running on interurban routes, range will be more of an issue. A company in the
UK claims to be the first operator of a Chinese built 50 seat battery coach with a range of 200
miles205 (321 km). This might not be a sufficient range for many coach routes, unless there are
rapid charge points along the route.
Hydrogen Buses
Hydrogen buses have been trialled for several years and there are examples of them inoperation. Transport for London has recently ordered 20 hydrogen buses to go with their 500
electric buses, with a target of an entirely zero emissions fleet by 2030206. Again, China has
the vast majority of the global fleet with 5,300207. There are some advantages to hydrogen as
the buses can be filled at the end of the day at the depot, which overcomes one of theinfrastructure issues faced by hydrogen cars, as it is relatively easy to install a hydrogen tankand pumps to service a large fleet.
Hydrogen also has a higher energy density than battery power, though less than diesel. Thiscan make hydrogen buses more suited to cities such as Hong Kong which are both hilly and203 https://www.bloomberg.com/news/newsletters/2021-08-13/electric-buses-are-poised-to-get-a-u-s-infrastructure-

boost#:~:text=There%20were%20about%20598%2C000%20e,nearly%201.7%20million%20in%202030.
204 https://www.fleetnews.co.uk/costs/carbon-footprint-calculator/
205 https://pelicanyutong.co.uk/coaches/tce12-electric-coach/
206 https://www.london.gov.uk/press-releases/mayoral/englands-first-hydrogen-double-deckers-launched
207 https://www.wired.co.uk/article/future-buses-hydrogen-electric#:~:text=Registrations%20of%20hydrogen%20cars%20remain,largely%20California)%2C%20and%20Japan.

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humid, where both conditions have been shown to drain electric batteries208. Battery
powered buses will operate perfectly well in relatively flat routes with short journey routes
where it is not unusually warm or cold.
4.4

HEAVY GOODS VEHICLESA White Paper from the International Council on Clean Transportation209 concludes thatelectric-drive heavy duty vehicle technologies are essential to fully decarbonise the transport
sector, with freight trucks representing less than 10% of all vehicles, but responsible for 40%
of emissions. They estimate that electric and hydrogen fuel cell technologies could be up to
30% cheaper to own, operate and fuel by 2030, although massive infrastructure investments
would be needed.
Electric
There are trials in the UK210, funded by the Department of Transport, of battery electric trucks
to be used by the National Health Service and Local Authorities, with the objective of the trial
to provide real world data to inform future buying decisions. These vehicles are provided by
DAF who were one of the first manufacturers to offer a range of battery electric trucks for
sale, including a 37-tonne vehicle with a stated range of 220 km211. Volvo has released abattery powered truck with a range of up to 300 km212, compared to a range of over 900 km
for a diesel truck in Europe from a single tank of fuel. In remote areas of Australia trucks haveadditional fuel tanks to achieve more than triple this range. Tesla is promoting is ‘Semi’ HGVwith a stated range of either 300 or 500 miles213 (482 to 804 km) with a network for fast truck
charge points to be developed, although production has not yet commenced.
Whilst there could be some shuttle routes with charging at each end it seems unlikely thatbattery electric trucks with current range would be viable for many operators in the shortterm. Should longer range vehicles become available, with a suitable network of fast chargers
where drivers need to take breaks, battery electric HGVs may become feasible. Although,there would be a large grid requirement and there could be logistics issues if vehicles had toqueue to charge and potential safety concerns if many vehicles were fast charging at the same
time.
There has been significant research, development and demonstration of electric road systems(ERS) in recent years, particularly in Sweden and Germany. PIARC commissioned a Special

208 https://www.wired.co.uk/article/future-buses-hydrogen-electric#:~:text=Registrations%20of%20hydrogen%20

cars%20remain,largely%20California)%2C%20and%20Japan.
209 https://theicct.org/publication/transitioning-to-zero-emission-heavy-duty-freight-vehicles/
210 https://www.leylandtrucksltd.co.uk/en-gb/news-and-media/news-article-folder/2022/battery-electric-truck-trial-hits-the-road
211 https://www.daf.co.uk/en-gb/trucks/alternative-fuels-and-drivelines/battery-electric-vehicles/daf-cf-electric
212 https://www.tu-auto.com/volvo-promises-full-electric-hgv-range-for-2021/
213 https://www.tesla.com/en_GB/semi

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Project on Electric Road Systems in 2018214 which presents the type of technologies andadvantages and disadvantages of each.
Whilst an ERS would require vehicle modification to add a pantograph or other charge
mechanism to the vehicle, theoretically, this could give an electric truck an unlimited range if
ERS were installed everywhere, but even electric driving and battery charging along parts of
the route, could extend the range of existing battery electric trucks to make them viable
alternatives to fossil fuel powered vehicles. There is a requirement for agreement of acommon standard for ERS to facilitate cross border transport.
Figure 16, below, shows a trial section of electric highway on the E15 highway in Sweden. The
lorry in this case is a hybrid, with a diesel engine to provide power when not on the trial
section.

Figure 16. eHighway in Sweden©Maple Consulting

Case study – Norway Coastal Highway Route E39
The Norwegian coastal highway route E39, located on the west coast of Norway (Figure 17),connects Kristiansand in the south to Trondheim in central Norway – a distance of 1100 km.
The route E39 runs through six counties with a total population of 1.8 million people215. Morethan half of Norway’s energy intensive industry is located along this road. The Ministry ofTransport and Communications has given the project “Coastal Highway Route E39” a mandate

214 https://www.piarc.org/en/order-library/29690-en-Electric%20road%20systems:%20a%20solution%20for%20the%20future
215 SSB 2014. Population by counties.: Statistics NorwayCARBON NEUTRALITY OF THE ROAD SECTOR

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to address challenges, possible technological solutions and to investigate social and economic
benefits of building fixed connection instead of using ferry connections 216. Examples of areas
under investigation are how the infrastructure can be exploited to generate renewable energy
and how the harvested energy can be used to reduce the ecological and environmental
footprint of the road infrastructure.

Figure 17. E39 Coastal Route Map217

Direct CO2 emissions from fuel consumption associated with road transportation on the E39
has been estimated to be 750 kton for year 2014, assuming a CO2 emission factor of 2.54 kg/lof diesel and 2.36 kg/l of petrol218. On this basis, significant research has been dedicated toinvestigating carbon reduction mechanisms on the route. One such investigation to reducecarbon was reviewed by Adl-Zarrabi et al.219. The research examined two biofuel blending
scenarios for a low ambition scenario of 20% biofuel for road vehicles and a high ambition
scenario of 40% biofuel. This was calculated to produce a 16% and 50% decrease in CO2emissions, respectively, assuming net zero CO2 emissions from biofuels. For the E39, thiswould mean a reduction of ~120-370 kton CO2/yr compared to the current level of 740
kton/yr, as seen in Figure 18. A change to hybrid electric vehicles, such as plug-in-hybrids,
could technically reduce the energy needed per vehicle km by 30%, and then potentiallyreduce CO2 emissions from E39 by approximately 220 kton/yr for the E39. However, to reach
low or zero emissions of CO2, a more complete transition to electricity or hydrogen seems to
be required. Electrification of the E39 could imply electric cars, fuel cells, conductive or
inductive charging integrated in the road infrastructure (for example over-headlines or

216 STATENS VEGVESEN. 2012. Coastal Highway Route E39 [Online]. http://www.vegvesen.no/Vegprosjekter/ferjefriE39/English
217 Ellevset, O., (2014), “Norwegian Coastal Highway Route E39”, Norwegian Public Roads Administration Presentation, Available athttps://www.cpci.pt/wp-content/uploads/2015/03/Autoestrada_E-39.pdf
218 NILSEN, Ø. L., STRIDH, M, STRIDH, SPILSBERG, E. 2014. Ferjefri E39 Trafikkberegninger Fase 1
219 Adl-Zarrabi, Bijan, et al. "Safe and sustainable coastal highway route E39." Transportation Research Procedia 14 (2016): 3350-3359

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ground-level supply). In summary, a transition to electric vehicles will have, in the long-term
perspective, the potential to reduce the CO2 emissions to almost zero.

CO2 Emissions for Road Transport E39 (kton/yr)
450
400

Current levelkton/yr

350
300

Biofuels low

250
Biofuels high200
Hybrid vehciles

150
100

Electric Vehicle Nordic elec mix

500Light vehicles

Heavy vehciles

Figure 18. E39 CO2 emissions when applying different possible reduction strategies (reproduced from 220)

HydrogenHydrogen has been promoted as a compelling option for long distance freight. Hyundai
manufactured the first mass-produced fuel cell truck221, with a claimed real-world range of
400km. The first ten trucks were delivered to Switzerland in 2020, with American
manufacturer Hyzon Motors moving into the European market in 2021. Hyzon has joined a
European consortium which plans to deliver 100,000 hydrogen fuel cell trucks in Europe by2030. Hyzon has also signed a memorandum of understanding with TotalEnergies to aid thetransition of fleet owners to hydrogen and to develop the infrastructure. Hyzon will deliver 80
trucks to TotalEnergies’ French customers by 2023222. DAF trucks’ parent company PACCAR is
exploring fuel cell technology with extensive trials around the Port of Los Angeles, whilst in
the UK, DAF is developing an internal combustion engine running on hydrogen 223. Volvo has
unveiled a hydrogen fuel cell vehicle with a claimed 1,000-kilometre range, capable of being
refuelled in 15 minutes224, however, it was pointed out that a lack of refuelling infrastructure
remains a hurdle with fewer than 60 stations operational in the USA, all in California, though
this predicted to nearly double in 2023. In Australia225 too, there has been investment in
220 Ellevset, O., (2014), “Norwegian Coastal Highway Route E39”, Norwegian Public Roads Administration Presentation, Available athttps://www.cpci.pt/wp-content/uploads/2015/03/Autoestrada_E-39.pdf
221 https://trucknbus.hyundai.com/global/en/products/truck/xcient-fuel-cell
222 https://fuelcellsworks.com/news/the-first-hydrogen-trucks-are-rolling-in-europe/
223 https://www.daf.co.uk/en-gb/trucks/alternative-fuels-and-drivelines/hydrogen
224 https://www.theverge.com/2022/6/21/23177624/volvo-trucks-tests-hydrogen-fuel-cell-semi
225 https://www.theguardian.com/environment/2022/jul/18/hydrogen-fuel-stations-to-be-built-between-sydney-and-melbourne-under20m-plan

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hydrogen infrastructure, with the Queensland, New South Wales and Victorian governments
funding refuelling stations on the east coast between Brisbane, Sydney and Melbourne. Other
manufacturers are also believed to be developing heavy hydrogen vehicles.
Not everyone is convinced that hydrogen has a future in road transport. Fraunhofer226 reportsthat they consider hydrogen vehicles have lost the advantage they once had in terms of range
and fast charging, and will be uncompetitive with battery electric vehicles. Even for heavy
vehicles, they consider the target of 100,000 vehicles outlined above challenging withcommercial production unlikely before 2027, by which time battery technology will have
moved on, and with fast chargers and the requirements for drivers to take regular breaks, therange will be sufficient to satisfy most operations. They believe there may be use cases forvery heavy vehicles in remote areas, but this will be a niche application.
It is also worth noting that at present, most hydrogen is produced in an energy intensive
manner using fossil fuels (grey hydrogen), although blue hydrogen (carbon capture andstorage of emissions) and green hydrogen (hydrogen produced by electrolysis of water, fromrenewable energy sources) are increasing.
Summary
Theoretically, all the vehicles on the road network
could be powered from net zero or carbon neutral
fuels. This could save over 5.6GT per year of CO2.
This would require strong international support andcoordination on standards and interoperability. NRAs
will have a key role in helping implement the solutions
on their networks.
The biggest savings to be realised in the short tomedium term, would be from more efficient use of the
network, such as active travel or increased use of

226 https://www.rechargenews.com/energy-transition/-hydrogen-unlikely-to-play-major-role-in-road-transport-even-for-heavy-trucks-

fraunhofer/2-1-1162055

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5 OPERATIONS ON THE ROAD NETWORK
5.1

VEHICLES OPERATED BY ROAD ADMINISTRATIONSRoad administrations have fleets of vehicles of various kinds from cars and vans to trucks andmaintenance equipment such as gritters and snow ploughs. Their use cases are essentially thesame as those discussed above although there are some specialised cases such as patrol andrecovery vehicles where the demands for payload and capability (e.g. towing) are morechallenging. Road administrations have an important role in testing and demonstrating theuse cases of alternate fuel vehicles, whilst helping develop the fuelling infrastructure as asingle depot that can service many vehicles.
For example, the FEHRL scanning tour of the USA227 in 2018 reports findings on a visit toCaltrans (California State Highway Department) who are actively pursuing a low emission
fleet, with targets for adoption of electric and hydrogen vehicles. In 2015, 10% of the Caltransfleet were EVs, with targets for 25% by 2020 and 50% by 2025 for light vehicles. For heavy
vehicles, the targets were 15% by 2025 and 30% by 2030. At the time of the report publication,
the fleet contained 73 battery electric vehicles, 152 plug in hybrid vehicles and 36 hydrogenfuel cell vehicles, as part of the overall light vehicle fleet. The response from users was
generally positive, particularly as the vehicles had a higher spec than the standard vehicles,
and no issues were reported with charging. There were at that time only 36 openly availablehydrogen stations, mostly in the LA and San Francisco Bay areas.
5.2

LED LIGHTING

Images of Europe taken by astronauts from the International Space Station demonstrate awidespread shift from high pressure sodium lighting to LEDs, with particularly notable
increases in Italy, Romania, Ireland and the UK228. Highway lighting can improve road safety
and increase drivers’ and pedestrians’ levels of comfort. Adequate lighting has been found to
reduce pedestrian accidents by around fifty percent229.
Public street lighting can account for between 30-50% of a typical city’s energy bill230. The
electricity consumption of lighting could increase by over 10% by 2030. Although, current
policies to improve lighting efficiency could decrease consumption to below current levels231.
The momentum for energy efficient lighting is growing to meet carbon targets and reduce CO2
emissions. Many countries are switching to LED technology to replace inefficient lighting
associated with high energy consumption and maintenance costs. LED lighting provides a high

227 https://www.fehrl.org/library?id=7721
228 Highways Magazine, October 2022, A LED Paradox (Highways Magazine (pagesuite-professional.co.uk)).
229 Box, P.C., Relationship Between Illumination and Freeway Accidents. IERI Project 85-67 Illuminating Research Institute, New York April,

pp. 1-83, 1970.
230 Pardo-Bosch, F., Blanco, A., Sese, E., Ezcurra, F., Pujadas, P., Sustainable strategy for the implementation of energy efficient smart public
lighting in urban areas: case study in San Sebastian. "Sustainable cities and society", 2022, vol. 76, p. 103454:1-103454:12.
231 United for Efficiency, Lighting - United for Efficiency (united4efficiency.org)

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quality, efficient and low maintenance solution, with LED lamps lasting up to 20x longer thanconventional lamps231.
Lighting of highways and roadways is essential to enable high visibility, improve safety andsecurity, allow for mobility, and improve the quality of life of citizens230. In 2012, one third of
the worlds road lighting systems were running on technology dating back to the 1960s232. It is
forecast that by 2027, 89% of the world’s 363 million streetlights will utilise LED technology230.
The primary source of power for street and highway lighting is the national grid. However, inmore remote areas, alternative options are sometimes preferable, such as, solar PV power
and wind power or hybrid systems. Solar panels convert solar radiation into energy during theday, which is stored in batteries for night-time use. A mini power station can be installed tohouse solar panels and batteries to power a group of lights, or panels and batteries can beinstalled on each pole233.
The efficiency of LEDs can be further supplemented by smart controls. Considering energy
savings, and the reduction in operation and maintenance costs, payback on initial investment
can in most cases be in the range of 4-8 years 230, 234. In many cases, existing lampposts andlighting systems cannot be adapted to incorporate smart technology, resulting in a high initialinvestment to purchase and install smart lampposts.
The business model in most European cities provides lighting throughout the night to ensure
visibility. Approximately 20% of electricity consumption globally is attributed to nocturnal
lighting systems235. Smart systems for public lighting integrate additional sensors and controls
to optimise use and improve efficient and energy use230. By using smart technology, lighting
levels and operations can be remotely controlled depending on the demand and site needs,
using sensors, data analysis and control units. This allows for the optimisation of output andenergy consumption236. The demand for Smart Street Lighting (SSL) has been increasingaround the globe. As a reference, there was an estimated 80,000 SSL units throughout 14
countries in 2008, which increased to a demand for 21.8 million SSL streetlight conversions in
2017, with the fastest growing markets in the US, UK, Germany, France, Italy, China, Japanand South Korea237.

232

Crowther, J., Herzig, C., Feller, G., The Time is Right for Connected Public Lighting Within Smart Cities, Cisco Philips Report, 2012.

233 Gillard, R., Oates, L., Kasaija, P., Sudmant, A., Gouldson, A., Sustainable urban infrastructure for all: Lessons on solar-powered street

lights from Kampala and Jinja, Uganda. Coalition for Urban Transitions (Policy Brief), March 2019.
234 State of the Nation 2020 Streetlighting Survey, UK Roads Liaison Group, CIHT (sotn-report.pdf (ciht.org.uk)).
235 Tannous, S., Manneh, R., Harajli, H., El Zakhem, H., Comparative cradle-to-grave life cycle assessment of traditional grid-connected andsolar stand-alone street light systems: a case study for rural areas in Lebanon, J. Clean. Prod. 186 (2018) 963-977.
236 Shehedeh, N.H., Sustainable Street Lighting: A Guide too Efficient Public Street Lighting for Lebanon, A UNDP-CEDRO Publication,
December 2015.
237 Al Irsyad, MI, Halog, A., Nepal, R., Smart grid technology for energy conservation in street lights: lesson learnt from six years’ operationin Indonesia. 2019 International Conference on Technologies and Policies in Electric Power and Energy, pp 1–6, 2019.

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Table 6 indicates the properties of different lighting technologies, comparing lifespan, capital
expenditure (capex) and operational expenditure (opex)236.

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Table 6. Lighting technologies comparative table (reproduced from 236)

Life cycle assessment was carried out to evaluate the environmental implications of two
potential lighting systems in rural Lebanon from cradle-to-grave238:••

Traditional grid system (steel pole, high pressure sodium lamp and aluminium cables)
Independent standalone solar powered system (a steel pole, a Light Emitting Diode lamp, aphotovoltaic panel, a valve regulated acid battery, a controller, a dimmer, and copper cables)

Considering the raw material extraction and production, the study indicates the traditional
system has less environmental impacts than the solar system. This is primarily due to the leadand electronics used as part of the solar system. However, considering the entire life cyclefrom raw material to end of life, including ongoing power requirements and recycling
capabilities, the solar system shows less overall environmental impacts.
Further discussion on policy, case studies and economic aspects associated with LED lighting
will be provided in Part 3 of this report.

238 Tannous, S., Manneh, R., Harajli, H., El Zakhem, H., Comparative cradle-to-grave life cycle assessment of traditional grid-connected andsolar stand-alone street light systems: a case study for rural areas in Lebanon, J. Clean. Prod. 186 (2018) 963-977.

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6 ROAD USER CHOICES
6.1

TRANSFER TO ACTIVE TRANSPORT

Non-motorised transport (NMT) infrastructure has significant health benefits for users, theenvironment and society in general. It has relevance across developed and developing
countries. In 2017, UNEP published a report on the Cost Benefit Analysis of NMT Infrastructure
Projects, as well as an accompanying Project Assessment Tool to estimate the potential
environmental, social, economic and health benefits from an increase in NMT. According to
the report, providing a well-planned, high-quality network of facilities for NMT is essential fordeveloping economic and social equity in urban areas of developing countries239. Case studies
are examined to provide insight into the implementation of NMT schemes in developing
countries.
As an example, Thika Highway is a 45km highway in Nairobi, giving access to employment,
education and other services. Issues with congestion, high accident rates and fatalities of nonmotorised transport users, provided motivation to improve NMT services by constructing
cycling facilities, pedestrian walkways and appropriate footbridges, with the aim of reducing
NMT user fatalities. The scheme was expected to increase the number of walking and cycling
trips, resulting in 3% reduction in CO2 emissions (19,911 tons CO2) from trips on the Thika
Highway by 2030239. However, there has been criticism of the scheme since completion of the
project, particularly in relation to the design and location of footbridges. As part of the Thika
Highway scheme, motorised transport formed most of the project. Following completion of
the project with improved NMT infrastructure, pedestrians still accounted for 84% of fatalities
along the corridor, which is higher than pre-construction levels239. Based on the Thika Highway
experience, the report provides recommendations for further schemes239:•••

Design of infrastructure considering the requirements of NMT from inception (e.g. in relation
to position of footbridges)
Provide NMT services as part of a network rather than a standalone service along a single
corridor
NMT infrastructure should be provided along popular NMT routes rather than as an add-on to
popular motorised routes

In terms of environmental benefits, as a comparison, it was predicted that the provision of
NMT infrastructure along the 1.4 km Haile Selassie Avenue in Nairobi will reduce CO2
emissions by 10% by 2030 (reduction of 12,909 tons CO2) due to an increase in pedestrian andcycling activities along the route239. It is predicted that strategic NMT infrastructure along thisshort route will have significantly greater benefits than Thika Highway239. A theoretical study
examining the effects of having an extensive walking and cycling network in the Nairobi
metropolitan network predicts a potential reduction in CO2 emissions of 5% by 2030 across
239 UNEP, Cost Benefit Analysis of NMT Infrastructure Projects, 2017, Cost Benefit Analysis of NMT Infrastructure Projects | UNEP - UN

Environment Programme.

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Nairobi as a result of an increased uptake of NMT, resulting in estimated CO2 emission savingsof 624,867 tons239.
Ghana has a large urban population of approximately 56%. Severe congestion in urban areas
drove the need for more sustainable modes of transport, and the development of the Ghana
NMT Strategy 2018-2028. The 10-year goals include240:
•
•
•
•
•

Integrate NMT into transport infrastructure
Provide basic NMT infrastructure
Facilitate access to bicycles and promote the use of bicycles
Improve road safety for NMT users
Regulate the design of new and existing roadway facilities.

A study on non-motorised transport was carried out by GTZ on behalf of the Federal Ministry
for Economic Cooperation and Development in Germany241. According to the report241, to
improve active user participation in NMT projects, users need to be involved in all aspects ofthe development and implementation of NMT projects. The following were suggested as
examples to engage users in the process241:•••

Focus Groups to identify current and potential problems and document themUser Platforms to communicate and prioritise user needs in the planning and implementationof NMT
User Associations to remain a major part of the maintenance and operation of the built NMT
infrastructure

A comparison of road space reallocation measures taken in two UK cities (as a response to
Covid-19 lockdown measures) found that only a relatively low proportion of the sample study
participants had used one of the temporary measures (32%). However, the users regarded
them overwhelmingly positively, particularly those measures that removed traffic242.
Copenhagen and Amsterdam are both capital cities with a bicycle friendly infrastructure andhigh cycling uptake. In these cities, private motorised vehicle transport ranks third or fourth
as a means of transport. To emulate this success, the Bicycle Referendum Initiative (Initiative
Volksentscheid Fahrrad) was established in Germany 2016 to increase the modal split in cities
with a low share of cyclists. As part of this initiative, in Essen, the following improvements areplanned and should be put in place by 2030 to improve cycling culture243:••

Provide a continuous network for everyday bicycle users
Make crossings safer for bicycle users

240 Ghana Non Motorized Transport Strategy,

UNEP - UN Environment Programme, Ghana Non Motorized Transport Case Study | UNEP UN Environment Programme.
241 Hook, W., Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH, Training Course: Non-motorised Transport, Federal
Ministry for Economic Cooperation and Development, 2005, Training Course Non-Motorised Transport (unece.org).
242 Parkes, S., Weston, R., Gore, T. and Lawler, M. (2021) Room to Move: Impacts of road-space reallocation. DecarboN8. DOI:
10.7190/cresr.2021.0383487418
243 Copenhagen and Amsterdam are not utopias, 2021, Copenhagenize your city | polisMOBILITY Magazine | polisMOBILITY (polismobility.com).

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Design bicycle paths and safe cycling lanes
Set up continuous and uniform cycling lanes
Increase the number of bicycle stands
Promote cycling as a mode of transport consistently and transparently

A study by Rojas-Rueda et al.244 examined data related to the public bicycle sharing initiative(Bicing) in Barcelona and concluded that the scheme had the effect of reducing annual carbon
dioxide emissions by 9062 tonnes per annum in 2011, by comparing with previous journeys
Estimated tonnes of CO2 savings associated with a sustainable transport hierarchy,
influencing various percentages of the UK population to change transport modes
Population percentage influenced
Passengers switching to

10%

20%

30%

Bus

5,800,000

11,750,000

17,650,000

Two
passengers
pervehicle6,800,000
13,600,000
20,400,000
made by cars.
Cycling
13,600,000
27,200,000
40,800,000
In 2012, Chen245 carried out a study to quantify the climate value of cycling in Dutch cities andthe total avoided CO2 emissions due to cycling. It was concluded that over a 5-year period,
through cycling, Dutch people avoided 1.36 million tons of CO2 per year245.
Consideration of active and public transport initiatives at preconstruction stage havesignificant potential to impact the way the public use our roads. It can be shown that the
average savings of an individual moving from private car travel to bus transport is around 0.9
tonnes CO2/year246, based on a UK average of 11,000 km. This value is around 1.0 tonnes/year
for making trips with a minimum of two people per car.
In 2021, the Department of Transport in the UK published plans for Decarbonising Transport,
highlighting the need to make public transport, cycling or walking the natural first choice forthose capable of doing so247. In 2019, 58% of all private car journeys were below five miles
and is an area with significant potential for behaviour change, switching from car journeys towalking or cycling. In the 16 months between March 2021 and June 2021, more than 300

244 Rojas-Rueda, D., de Nazelle, A., Tainio, M. and Nieuwenhuijsen, M.J., 2011. The health risks and benefits of cycling in urban

environments compared with car use: health impact assessment study. BMJ, 343.
245 Chen, Y., Assessing Climate Value of Cycling Under Different Urban Forms of Dutch Cities. Dissertation for the University of Twente,
Faculty of Geo-Information and Earth Observation (ITC), 2012.
246 Which form of transport has the smallest carbon footprint? - Our World in Data: https://ourworldindata.org/ travel-carbon-footprint
247 Department of Transport, Decarbonising Transport - A Better, Greener Britain, 2021, Decarbonising Transport – A Better, Greener
Britain (publishing.service.gov.uk).

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cycling and walking schemes were installed, with many more proposed over the next 5 years.
With a £2 billion investment, the aim is for half of all journeys in towns and cities to be cycled
or walked by 2030. A massive 46 percent increase in cycling was observed in 2020, which was
greater than the previous 20 years combined. However, it is also recognised that this increaseis partly due to changes in habits and lifestyle due to the coronavirus pandemic. In the UK,
new operating models are transforming traditional transport services, e-cycles as well as otheremerging technologies are providing increased opportunities to travel distances that would
have previously been considered too long to cycle. Based on the plans outlined in
Decarbonising Transport, a reduction in car GHG emissions between 1 to 6 MtCO2e ispredicted in England between 2022 and 2050.
In Wales, in addition to the Active Travel Act 2013, the new Wales Transport Strategy has set
a target objective of 45% of journeys to be made by walking, cycling and public transport by
2040. To facilitate this modal shift, the dedicated budget for active travel infrastructure has
been increased from £5 to over £20 per head of population per year between 2013 and2021248.
The government of British Columbia published a CleanBC Roadmap249 to outline measures toreduce carbon emissions by 2030. In the document, a plan to encourage modal shift to moreenergy efficient forms of transport is outlined. As such, energy intensity targets for personaltransportation will be established which will work to increase the share of trips made bywalking, cycling and public transport by 30% by 2030, 40% by 2040 and 50% by 2050 249.
“Move. Commute. Connect.” Is British Columbia’s active transport strategy to improve
walking, cycling and other modes of active transport and make them safe and accessible forpeople of all ages and abilities. Infrastructure and planning grants are available to Indigenous
and local governments to support active transportation improvements. Tax incentives areincluded to encourage the use of eCycles as an active transport option and $18 million was
allocated in the 2021 budget towards provision of active transportation infrastructure250.
As part of its Sustainable Mobility Policy, the Canadian Province of Québec has a ‘RTI’
strategy251; Reduce – Transfer – Improve, focusing respectively on reducing motorised trips
and distances by integrating land use and transportation, transferring trips to lower emission
options, such as public transport and active travel, and improving the efficiency of vehicles byreducing their carbon footprint, but also improve trips in terms of costs, quality and safety.
6.2

TRANSFER TO PUBLIC TRANSPORT

248 Active Travel Act Guide, Llwybr Newydd, Welsh Government, 2021, Active Travel Act guidance (gov.wales).
249 CleanBC Roadmap to 2030, Government of British Columbia, CleanBC Roadmap to 2030 (gov.bc.ca).
250 Clean Transportation - How we’re making it easier to get around without a car, Government of British Columbia, Clean transportation -Province of British Columbia (gov.bc.ca).
251 https://participatoryplanning.ca/community/quebecs-sustainable-mobility-policy

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According to the U.S. Department of Transport, bus is the most common form of public
transport and using public transport instead of personal vehicles produces on average 45%
less CO2 per passenger mile252. A study conducted by the American Public Transportation
Association253 indicated that the most effective way to reduce household carbon emissions
was to use existing public transportation instead of driving a private car, as illustrated in Figure
19. In the Public Transportation’s Contribution to USA Greenhouse Gar Reduction report,
Davis et al.254 estimated a reduction of 6.9 MtCO2 in USA in 2005 by using public transport due
to the reduction in emissions from private cars and from reduced congestion (Table 7).

Pounds of CO2 saved per year

6000
5000
4000
3000
2000
1000
0
Taking public
transport to work

Adjustingthermostat

Replacing lightbulbs

Replacing old
refrigerator

Figure 19. Household CO2 savings from using public transport instead of private car (reproduced from 253)
Table 7. Estimate of the benefits of public transport in reducing CO2 emissions in USA in 2005 (reproduced from 254)

Estimated CO2 Savings in USA from Using Metric Tonnes
Public Transport (2005)
Carbon dioxide emissions from personal 16.2 million
vehicles if no transit service
Carbon dioxidetransportation

emissionsfrompublic 12.3 million

252 U.S. Department of Transportation, Public Transportation Trips Per Capita, 2015, Public Transportation Trips Per Capita | US

Department of Transportation.
253 American Public Transport Association, Public Transportation Reduces Greenhouse Gases and Conserves Energy,
greenhouse_brochure.pdf (apta.com).
254 Davis, T., Hale, M., Public Transportation’s Contribution to U.S. Greenhouse Gas Reduction, Science Applications International
Corporation, 2007, https://www.apta.com/wpcontent/uploads/Resources/resources/reportsandpublications/Documents/climate_change.pdf

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Net carbon dioxide saved from public 3.9 million
transportation
Additional carbon dioxide saved from transit 3.0 million
reduced congestion
Total carbon dioxide savings from public 6.9 million
transportation
Public transport includes the use of buses, trains, coaches, and trams. A passenger centred
approach is required to provide a genuine alternative to private vehicles. Incentives can beoffered to help reduce the use of personal vehicles and increase the use of public transport.
According to the U.S. Department of Transportation, reducing the cost of public transport tothe user, including free or discounted bus, rail and/or tram, can be one incentive to increase
public transport use. Other incentives including travel passes, reimbursements, tax reductions
and subsidies have been shown to increase public transport use in the US. Considering upfront
and ongoing costs of car ownership (e.g., vehicle cost, tax, insurance and ongoing
maintenance), the costs associated with using public transportation are generally lower thancosts associated with ownership of private vehicles255.
However, for public transport to be effective it needs to be reliable, affordable and efficient.
Integrated public transport, both door to door and adequate walking and cycling facilities toaccess public transport services and transfer between modes is essential. Up to date accurate
information on journey times promotes user confidence, making movement between
transport modes feasible and stress-free256. Public transport also needs simpler and easy tonavigate payment systems, e.g. contactless payments and multi-modal tickets for trains, buses
and trains. It also needs to be affordable, competitive with the cost of private transport, andwith flexible tickets that fit new travel patterns. Examples of a single public transport payment
card are Oyster (London), Leap (Dublin) and Octopus (Hong Kong).
As part of the UK target for net zero emissions by 2050, a fundamental reshape of the public
transport bus network is planned. The aim is to provide more priority lanes for faster andreliable travel and lower, simpler fares, as well as zero emission buses. Policies like these havesuccessfully contributed to modal shift in London:••

20% decrease in the share of solo car trips at a national level
40% reduction in oil consumption in the transport sector below the level from 2013

255 U.S. Department of Transport, Expand Public Transportation Systems and Offer Incentives, 2015, Expand Public Transportation Systems

and Offer Incentives | US Department of Transportation.
256 Campaign for Better Transport, Integrated Transport: A New Generation of Interchanges, 2018, integrated-transport-a-newgeneration.pdf (bettertransport.org.uk)

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The goal is to provide similar service in other parts of the UK, with simpler, cheaper fares, paid
for using contactless cards and with daily and weekly price capping across different
operators247.
Hong Kong has an extensive public transport system. The compact nature of the city and asophisticated network mean that public transport is accessible from almost anywhere.
Benefiting from a clean, safe, fast, efficient service, almost 90% of the population use thepublic transport system257. Private vehicles are also discouraged by introducing parking fees
and high taxes on imported vehicles258.
Kenya has a high uptake in public transport use, with 63% of the population using public
transport. This can be largely attributed to the high cost of car ownership, high fuel cost andsevere traffic congestion, particularly in Nairobi258.
Following a trial which began in September 2015, in September 2017, Dunkirk became thelargest metropolitan area in Europe to remove fees on the entire public transport network,where one of the aims was to promote more sustainable travel within the city. The scheme
included a major overhaul of the bus system, with 5 bus rapid transit (BRT) lines key to theoperation of the network, with the ability to provide a high level of service due to dedicatedrights of way along the lines. The aim was to provide a bus every 10 mins on each line between
7am and 7pm259. Eight months after the scheme was introduced, use of the bus lines had
increased by 65% during the week and by 125% during the weekend. As well as an increase inuse by people already using public transport, a study of automatic counting systems on buses
along with a survey of 2,000 people found that there were also new users of the public bus
system. Of people who had previously used the service, 50% indicated that they now used it
for journeys previously travelled by car260. Of those surveyed, 10% of people indicated it
removed the need for a car, with some deciding to relinquish ownership of cars and others
decided against purchasing a new or second car261.
Although Dunkirk is a relatively positive success story, studies indicate that the choice to use
public transport over private vehicles has more to do with service quality than cost. In somecases, it is more effective to increase the cost of using a private vehicle, like fuel costs,
congestion taxes or parking charges262.

257 World Atlas website, The Top 10 Best Public Transit Systems in the World, 2018, The Top 10 Best Public Transit Systems in the World -WorldAtlas
258 World Atlas website, Countries with the Highest Public Transit Use, 2018, Countries With the Highest Public Transit Use - WorldAtlas.
259 Modijefsky, M., Free public transport launched successfully in Dunkirk, Eltis website, 2018, Free public transport launched successfullyin Dunkirk | Eltis.
260 Urbis magazine, Dunkerque: Le Bus Gratuit Séduit Les Automobilistes, 2019, Dunkerque : le bus gratuit séduit les automobilistes - URBIS
le mag.
261 Modijefsky, M., Free public transport in Dunkirk, one year later, Eltis website, 2019, Free public transport in Dunkirk, one year later |Eltis.
262 Deutsche Welle (DW) website, Can free public transport really reduce pollution?, Can free public transport really reduce pollution? |Environment | All topics from climate change to conservation | DW | 14.02.2018.

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A study carried out in Korea examined if the introducing free public transport would instigate
a modal shift in transport. In a survey, 51% of participants indicated that free public transport
would not alter their transport behaviour, stating inconvenient location for transfer to andfrom public transport263. The study concluded that while eliminating fares, increasing comfort
and optimising routes increases public transport use, additional strategies like replacing car
lanes with bus lanes, reducing parking and implementing congestion fees may be required toencourage users to switch from private vehicles to public transport 263. The goal is to reduce
private vehicle trips and not compete with non-motorised transport modes, a desirable
outcome would be a public transport network that integrates and complements walking andcycling initiatives263.

263 Zhen, S., Free public transportation: Why we need it, and examples from Korean and European cities, ICLEI Korea – Sustainable Mobility,

2021, Free public transportation: Why we need it, and examples from Korean and European cities - ICLEI Sustainable Mobility.

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7 CARBON OFFSETTING
The concept of carbon offsetting is simple; carbon emitted from one source (e.g. burning fuelto power a vehicle) is counteracted by carbon removed from the atmosphere by anothermeans, (e.g. by planting a tree which absorbs CO2 from the atmosphere as it grows). Various
companies offer offsetting schemes: for companies these offer to offset operational emissions(e.g. energy used to manufacture a product) and, for individuals, to offset the emissions fromtheir lifestyles (e.g. heating, lighting, vehicle use and diet, specifically meat consumption).
Different offsetting schemes (see below) have specific areas of focus, but the project choices
are similar, such as funding renewable energy projects, tree planting, peat bog restoration,
blue carbon restoration (mangrove plantations, saltmarsh creation or restoration andseagrass restoration), provision of low carbon stoves and prevention of deforestation. These
schemes should be additional to actions that would have occurred anyway, to ensure there isa genuine and equal reduction in emissions to those being compensated for.
7.1

METHODS TO REMOVE CARBON

Carbon sequestration

Carbon sequestration refers to the methods in which carbon can be stored and therefore‘locked in’, reducing overall CO2 quantities in the atmosphere. There are doubts about thepotential benefits, costs and technical feasibility of scale up of several methods of carbon
sequestration. Reduction in carbon emissions should always be the first choice in the fight tokeep global temperatures at or around 1.5OC by 2050.
The UK Government has provided £70 million of funding for trials264 of methods for theremoval of greenhouse gases. The funding falls into the general categories listed below, withdetails on the specific projects funded available on the competition homepage265.
Afforestation

Establishing new areas of forest though tree planting results in the removal of atmosphericCO2, as the trees grow, as well as potential for increased biodiversity and improved soil
condition. However, there are concerns about the use of non-native species and the amountof land required (and possible implications for food security). There is also a debate onwhether to plant woodland, which has more biodiversity but is slower growing, and forests,
which grow more quickly and therefore absorb CO2 more quickly but may be lacking indiversity. A useful overview, summarising progress in afforestation in China, North Africa andIndia, is provided by Vartan266.

264 https://www.theguardian.com/environment/2022/may/30/greenhouse-gas-removal-not-a-silver-bullet-to-achieve-net-zero
265 https://www.gov.uk/government/publications/direct-air-capture-and-other-greenhouse-gas-removal-technologies-competition
266 Vartan S (2022) What is Afforestation? Definition, Examples, Pros and Cons. https://www.treehugger.com/what-is-afforestation-

definition-examples-5114137

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Storing in soil

Soil naturally stores carbon and improving soils can therefore store it more effectively. Thereare concerns though about how long it stays in the soil and how to measure it. If it werereleasing carbon soon after storage, it could still be counted in net zero targets, but not
actually reducing carbon.
Enhanced weathering

This involves dropping small rock particles into the sea to cause chemical reactions that lockcarbon in the ocean but is at an early stage. As the oceans stores carbon in higher
concentrations than the atmosphere, it has potential and may even help reverse ocean
acidification, however there might be unknown harmful effects on the ocean ecosystem.
Biofuels

The use of biofuels removes the need for fossil fuels to be used and so become cyclical,
however there are concerns around land use and potential competition with food crops, andbiodiversity loss as the growing of the crops often creates a monoculture, although
presumably this can be managed.
BiocharBiochar is a charcoal-like product produced from heating wood or other biomass in theabsence of oxygen. It can be applied to land to sequester CO2 in soils for an extended period.
This could be relatively easy and cheap, but there are concerns as to how long the carbon
would be stored, and whether it would have any negative impacts on the soil.
Direct air capture

Air is sucked from the atmosphere with a large fan and CO2 extracted and stored permanently
in rocks. The process has been technically proven, but it is very energy intensive and this needs
to be reduced to make scientific sense as well and becoming commercially viable.
Rewilding

There have been examples of rewilding, including the reintroduction of missing creatures torestore a lost balance in the ecosystem which may in turn, help reduce carbon emissions; forexample: conservation of sea otters267 in the Pacific to feed on sea urchins, who if leftunchecked decimate kelp forests, which are large carbon stores; the reintroduction of wolves
in Yellowstone has restored an apex predator and reduced deer browsing, helping forests toreturn268. Rewilding Britain note269 that trees self-seeding is generally a more effective meansof tree planting whilst creating a richer habitat, whilst other environmental benefits not

267 https://www.theguardian.com/environment/2016/jul/10/sea-otters-global-warming-trophic-cascades-food-chain-kelp
268 https://www.theguardian.com/environment/2020/jan/25/yellowstone-wolf-project-25th-anniversary
269 https://www.rewildingbritain.org.uk/support-rewilding/our-campaigns-and-issues/climate-emergency

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related to carbon can be achieved, such as reintroducing beavers270 into Devon (UK), where
the dams have been shown to reduce flooding.

7.2

OFFSETTING SCHEMESAll the schemes271 listed below use 3rd party certified projects to give confidence that funds
go to projects that actually reduce emissions. Examples include Gold Standard, Verified
Carbon Standard, Climate Action Reserve, American Carbon Registry, Plan Vivo, Climate, andCommunity & Biodiversity Alliance. The schemes and the type of activities each employ are:
•
•
•
•
•

•

7.3

Native Energy – emissions reduction and reforestation
Sustainable Travel International – focussed on sustainable tourism – emissions reduction,
reforestation and blue carbon (mangroves, sea grass and salt marshes)
Terrapass – focus on large events – believed to be renewable energy and water restoration
Clear – focus on commuting, efficiency of cookstoves, hydroelectric plants, wastewater
treatment plants and sources of clean energy
Myclimate – focus on household emissions – funds projects in Biogas, Biomass, Efficient cook
stoves, Energy Efficiency, Hydro power, Land Use and Forestry, Solar, Waste Management andCompost, Water (Purification & Saving) and Wind
3Degrees – focus on business – good for companies seeking large offsets. Works on carbon
reduction and carbon removal and includes sustainable forestry, livestock manure
management, landfill gas, and industrial processes.

LIMITATIONS OF OFFSETTING SCHEMESOne limitation of offsetting schemes is the scale of offsetting needed to offset the emissions
associated with road transport. In terms of tree planting, it is reported 272 that a tree will
absorb around 20 kg of CO2 per year when fully grown, whereas a sapling will absorb muchless. Over a 100-year lifetime it is estimated that a tree will absorb around 1 tonne of CO 2.
Emissions273 from passenger cars alone in 2020 was around 3 GtCO2/yr – to offset this by tree
planting, even based on mature trees absorbing 20 kg per year with a 100% survival rate,would require 150 billion trees to be planted each and every year.
While tree planting has many beneficial aspects, these projects cannot lock carbon awaypermanently, or at least for thousands of years, as trees burn down, die from disease, or get
chopped down. There has also been criticism274 that many large tree planting schemes exist
on paper only, as there is little follow up, so many trees have died or been harvested. The
same report notes that 88% of a mangrove plantation in the Philippines failed after 5 years as

270 https://www.exeter.ac.uk/research/creww/research/beavertrial/
271 https://www.treehugger.com/best-carbon-offset-programs-5076458
272https://www.viessmann.co.uk/heating-advice/how-much-co2-does-tree-absorb#:~:text=How%20much%20CO2%20can%20a,around%20a%20tonne%20of%20CO2.
273 https://ourworldindata.org/co2-emissions-from-transport
274 https://www.bbc.co.uk/news/science-environment-61300708

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the wrong type were planted. Furthermore, many large-scale projects do not have the data or
follow up to even make such an assessment.
Similarly, while biochar can potentially lock carbon in for long periods of time (examples ofbiochar, several thousand years old, have been found in soils), in other situations it
decomposes rapidly (considerably less than 50 years), releasing the carbon back in theatmosphere. A thorough literature review identified only 15 papers that measured indicatorsof biochar composition in soil, in settings as varied as Colombia, Kenya, Zimbabwe, Canada
and USA275. While noting that biochar could be advantageous in the right circumstances, it
concluded there is currently insufficient evidence to estimate the stability of biochar over timeand recommended it is too early to be confident in it as an effective climate mitigation tool.
Some offsetting schemes prevent deforestation; however, Friends of the Earth reference areport276 funded by the German government suggesting that, even in areas where there arehigh historic rates of deforestation, it is difficult to determine what will happen in future.
Furthermore, even if a scheme does prevent deforestation in one location, it might just shift
it elsewhere as the driver for deforestation (e.g. farmland for livestock or crops) remains.
They state that the EC report says that most schemes who claim emissions savings fromchanging from inefficient cooking stoves to efficient ones, exaggerate the savings, whilst
noting a tonne of carbon is not always equal – a tonne emitted from a plane at altitude causes
more damage than a tonne of carbon burnt at ground level.
Friends of the Earth277 cites a study for the EC into UN sanctioned offset projects and foundthat three quarters were unlikely to have resulted in additional emissions reductions (as theywould likely have happened anyway), with only 2% having a high likelihood of being‘additional’. For energy, it is reported that many typical schemes will go ahead anyway,
because of a strong demand for energy combined with a market that will pay for it, andgovernments pledges to reduce emissions.
Overall, however, they pointed out that even the prospect of being able to offset prevents
businesses and individuals taking action to reduce emissions, i.e. if there might be a ‘get outof jail free’ card in a few years’ time, where we can plant some trees or have a machine suckcarbon out of the air, we don’t need to take significant action now.
Greenpeace278 come to the same conclusions that whilst tree planting and providing efficientcooking stoves are good, they don’t really offset the emissions to which they are linked andthey should be done as well as cutting emissions directly, not instead of it. They also point out
that it might take a tree 20 years to capture the carbon that a carbon offset scheme promises,

275 The scientific basis for biochar as a climate change mitigation strategy https://www.ucsusa.org/resources/biochar-climate-change-

mitigation-strateg
276 hhttps://climatefocus.com/publications/should-forest-carbon-credits-be-included-offsetting-schemes-such-corsia/
277 https://friendsoftheearth.uk/climate/does-carbon-offsetting-work
278 https://www.greenpeace.org.uk/news/the-biggest-problem-with-carbon-offsetting-is-that-it-doesnt-really-work/

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so we would have to plant and protect a massive number of trees for decades. Wildfires,
droughts and tree diseases could wipe out forests, whilst changes in the climate might put
strain on forests in future (although in some locations, higher temperatures and higher levelsof atmospheric carbon might promote faster growth).

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PART C – Case Studies
8 LED LIGHTING
8.1

CURRENT GUIDELINES AND TARGETS

With many NRAs striving to reduce energy bills and CO2 emissions, it is expected that LED
lighting will become the dominant technology for street lighting. Guides and standards by
the European Commission (EC) and United Nations Environment Programme – United For
Efficiency (UNEP-U4E), as well as national bodies, assist in this transition by providing
guidance and an outline of the options available.
In 2017, the European Commission published the EU GPP Criteria for Street Lighting &Traffic Signals, reviewing relevant technical, policy, academic and legislative literature toassess the potential for reducing environmental impacts and electricity costs byimplementing recent advances in energy affecting lighting technology. The provision oflighting on 1.6 million km of roads in 28 EU countries costs public authorities almost €4000
million each year, with an electricity consumption of 35 TWh, accounting for 1.3% of total
electricity consumption279. Similarly, the UNEP-U4E initiative published Green Public
Procurement Technical Guidelines and Specifications for Energy-Efficient Lighting in March
2022280. Additionally, in 2017, U4E developed an open-source Efficient Lighting Savings
Forecast Model, with the aim of helping users to model potential savings from moving toenergy efficient lighting281.
Specific examples from countries include:•••

The Danish EPA has a Total Cost of Ownership (TCO) tool to evaluate the total cost over the
lifecycle of a product, assisting procurers in assessing the possible advantages of purchasing
resource efficient products and products with a longer lifespan. Using this tool, as part of atender for lighting, Syddjurs Municipality in Denmark concluded that that the lifecycle costsof LED bulbs are 6 times lower than equivalent halogen bulbs282.
In the UK, National Highways has an ambitious aim for net zero travel on roads by 2050.
Part of this plan is to replace 70% of all road lighting with LED technology by 2027283.
Switching network lighting to LEDs will account for 12% of the overall emissions reduction
target between 2017 and 2030283.
In 2017, the province of Alberta’s Government published a LED Luminaire Specification
focusing primarily on the specification for LED products to replace 150-400W High Intensity

279 European Commission (EC), EU GPP Criteria for Street Lighting & Traffic Signals, 2017.
280 United Nations Environment Programme United for Efficiency (UNEP-U4E), Green Public Procurement Technical Guidelines andSpecifications for Energy-Efficient Lighting, 2022.
281 United for Efficiency (U4E - Model), Efficient Lighting Savings Forecasting Model - United for Efficiency (united4efficiency.org), 2017
282 Jones, M., Kinch Sohn, I., Lysemose Bendsen, A. M., Circular Procurement Best Practice Report, ICLEI – Local Governments for
Sustainability, SPP Regions, 2017.
283 National Highways, Net Zero Highways: Our 2030 / 2040 / 2050 plan, 2021.

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•

•

•
•
•
•

8.2

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Discharge (HID) lighting systems. The goal of using LED technology for roadway illumination
was outlined in a Specification document284.
In 2019, the province of British Columbia published a guidebook on converting to andpurchasing LED street light luminaires, indicating the procedure for purchasing LED
streetlights285.
The Second National Energy Efficiency Action Plan for the Republic of Lebanon outlines a
strategy for implementing energy efficient street lighting, by replacing high-pressure
sodium lamps with new LED lamps286. There are programs and initiatives in place in
Lebanon to support a shift towards energy efficient street lighting using LED and renewableenergy-powered lighting systems, mostly in the form of direct central government
purchases and grants from international organisations236.
In 2018, the Republic of Rwanda Ministry of Infrastructure published an Energy Section
Strategy Plan for 2018/19 – 2023/24, where several high-level targets were set out. One of
the targets was to expand street lighting to all populated areas and main roads. The work
was divided into three categories:
Existing national roads
Main roads in Kigali city and urban areas
New main national roads and roads under construction
High-quality LEDs or efficient Compact Fluorescent Lamps (CFLs) were recommended toreduce the electricity demand and operation and maintenance costs287.

BUSINESS CASE – CASE STUDIES

Average Sales Price ($)

Over the years, as the cost of LED lighting has reduced (Figure 20), the business case formoving towards energy efficient lighting has strengthened significantly. The economic
benefits of the transformation towards energy-efficient LED street lighting are discussed
through various case studies around the globe, where LED lighting offers longer lifetimes,
reduced energy consumption, and lower maintenance costs when compared with older
technologies. However, from the assessment of different case studies and targets in HIC
and LMIC countries the requirements and challenges must be considered on a case-by-casebasis to get the most effective solution.
50
40

30
20
10
0
2010

2012

2014

2016

LED

CFL

2018

2020

284 Alberta Government, Light Emitting Diode (LED) Luminaire Specification, 2017.
285 British Columbia, How to Purchase LED Street Light Luminaires through the LED CSA, 2019.
286 Lebanese Republic, The Second National Energy Efficiency Action Plan for the Republic of Lebanon NEEAP 2016-2020, Ministry ofEnergy and Water, 2016.
287 Republic of Rwanda, Ministry of Infrastructure Energy Section Strategy Plan 2018/19 – 2023/24, 2018.

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Figure 20. Reduction in sale price of retrofit LED lamps and CFLs replacement for a 60W incandescent lamp (reproduced
from 288)

Case Study 1: Indonesia (LMIC)
In 2011, due to an electricity crisis, the Government of Indonesia ordered a reduction inenergy consumed by streetlights by 50%, from midnight until dawn. This led to theintroduction of a pilot Smart Street Lighting (SSL) initiative in the city of Jakarta in 2012,and encouragement for other municipalities to follow suit. The growth of SSL technology
in Indonesia is expected to continue and has the potential to result in energy savings of up
to 300 GWh/year237.
Following the installation of SSL in 6 municipalities in Indonesia, it was recommended thatthe process be carried out in three stages. The first was to install energy meters and remove
fixed price contracts. The second was replacement of traditional mercury vapour (MV),low-pressure sodium (LPS) and high-pressure sodium (HPS) with induction and LED lamps.
These steps in Jakarta reduced total energy bills by up to 33%237. The third stage was theintroduction of dimming capabilities of SSL. Implementing a schedule of dimming theintensity of lights at different intervals throughout the day resulted in energy savings of
between 59% and 63% compared to conventional 250W HPS lamps without dimming.
As well as energy and carbon savings, there are additional benefits from SSL, including a
reduction in the cost of routine patrolling of street lighting systems to detect vandalism.
The SSL features also provides added capability to detect illegal connections237.
Al Irsyad MI et al. reviewed the lessons learned 6 years after the introduction of SSL237. It
showed that maintaining the operation of SSL at maximum efficiency over long periods
would be difficult due to inexperience of staff and staff turnover. The ongoing cost of CMS
systems and internet data was another challenge highlighted. One recommendation to
improve long-term performance and efficiency was to promote cooperation with energy
service companies to provide support with technical issues faced by municipalities289. Thishighlights potential for “lighting as a service” for expanding the use of LED technology forstreet lighting.
Case Study 2: Uganda (LMIC)
In the cities of Kampala and Jinja in Uganda, it proved more cost effective to install solar
powered street lighting than conventional grid powered streetlights. In developing cities,
the roads and streets can be unplanned, and services and infrastructure poorly managed.
This, in some instances, results in narrow roadways, where additional roadside space for288 United for Efficiency, Accelerating the Global Adoption of Energy-Efficient Lighting, Policy Guide Series, 2017.
289 Al Irsyad, MI, Halog, A., Nepal, R., Smart grid technology for energy conservation in street lights: lesson learnt from six years’operation in Indonesia. 2019 International Conference on Technologies and Policies in Electric Power and Energy, pp 1–6, 2019.

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grid-connectivity can prove problematic. In such cases, standalone solar powered lighting
units can be more advantageous and cost effective290.
Solar lighting also has the added benefit of providing lighting for roads when there are
power outages, particularly in many developing countries. The installation of solar lighting
not only improved road safety, but also lowered crime rates and accommodated a morevibrant night-time economy, created jobs and increased property values290.
At the time of publication by Gillard et al., the installation of solar powered lighting was in
the early stages in both cities of Kampala and Jinja290. In Kampala, most of the 1,800 solar
lights installed up to that point were on new or renovated roads, with a few replacing
conventional lights. Even on new roads, the installation cost of solar powered lighting is
generally lower than conventional grid powered lighting290. On average, for this initiative,
the cost was reported to be approximately 1,600 USD per solar lighting unit, compared to$2,150 for an equivalent conventional grid powered lighting pole. Solar powered solutions
offer almost zero operating costs and reduced ongoing maintenance costs259. The progress
is being evaluated closely to determine the viability of expanding the initiatives to other
cities.
Based on the success of the systems in Kampala and Jinja, the study by Gillard et al.
indicated that installing and maintaining solar powered LED streetlights across sub-SaharanAfrica could reduce installation costs by about 25%, electricity usage from street lighting by
40% and maintenance costs by up to 60% compared to conventional grid powered options.
In Uganda alone, if the 2,800km of urban roads were fitted with conventional grid-based
lighting, the cost would be approximately $238 million. Alternatively, installing solar
powered street lighting would result in an initial cost of $178 million, with no ongoing
electricity costs290.
Case Study 3: India (LMIC)The Street Lighting National Programme was launched in 2015 to replace conventional
streetlights across India with smart and energy efficient LEDs. In 2021, in urban areas,
Energy Efficiency Services Limited (EESL) installed over 10.9 million LED streetlights acrossIndia, resulting in energy savings of up to 7.34 billion kWh per year, resulting in savings of
up to INR 51,300 million per year (approximately converts to 620 million USD) in electricity
bills291. EESL also installed 2.6million LED streetlights in rural areas of Andhra Pradesh,
Jharkhand, Goa and Telangana291. Progress and savings to date can be tracked on the EESL
website, where the energy savings per year are estimated at 8,587 million units ofelectricity (1 unit = 1kWh), with GHG Emissions Reduction of 5.92 million tCO2292 (datareported on 24/05/2022).

290 Gillard, R., Oates, L., Kasaija, P., Sudmant, A., Gouldson, A., Sustainable urban infrastructure for all: Lessons on solar-powered street

lights from Kampala and Jinja, Uganda. Coalition for Urban Transitions (Policy Brief), March 2019.
291 JournalsOfIndia, Street Lighting National Programme (SLNP) , (Street Lighting National Programme (SLNP) - JournalsOfIndia), 2021.
292 EESL website, Streetlight National Programme – Dashboard, (https://slnp.eeslindia.org).

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Case Study 4: Lebanon (LMIC)A UNDP-CEDRO publication in 2015 reviewed street lighting currently installed in Lebanon
and assessed feasible options for future development293. In 2015, grid powered HPS werethe most widely used form of lighting in Lebanon but there was growing interest in LEDs
and solar street lighting. Considering current lighting in Lebanon and advances in energy
efficient lighting available, 10 options were examined including HPS, LED and induction
lighting, with different energy sources and varying levels of smart technology included in
the assessment. Each of the 10 options was studied in terms of technical, financial andenvironmental factors for a variety of different road specifications.
Each option was analysed considering initial investment cost, operations and maintenancecost and replacement cost, for a 1 km roadway for a period of 20 years. The results
indicated LED lamps to be the most cost effective for all road specifications, with grid
powered LED lamps having the lowest lifecycle cost and HPS and inductive lamps having
the highest costs293. Taking account of possible smart control systems, grid poweredsystems with advanced control presented the most cost-effective solution followed by grid
powered with basic control (timer and photocell) and solar power with advanced control(intelligent control based on traffic, light, date and time, weather conditions).
Environmental analysis demonstrated that renewable energy powered systems have thelowest emissions due to the absence of fossil fuel-generated power. A business analysis ofpossible retrofit options indicated that for all road types, new installation of grid powered
LED lamps with basic control measures showed a higher Internal Rate of Return (IRR) than
the retrofit of existing installations.
Case Study 5: San Sebastian, Spain (HIC)San Sebastian has a system of over 30,000 streetlights with an annual energy cost of €3.5
million and maintenance cost of €1.8 million. Before beginning the switch to LEDs, mostlighting relied on older generation High Pressure Sodium Vapour (HPSV) lighting. Pilot
implementations were carried out to provide an intelligent lighting network including
smart lampposts and sensors, resulting in a more efficient, cost effective andenvironmentally friendly system. For the pilot district, the scheme was divided into twozones depending on the intensity of lamps being replaced (52 x 250 W lamps relaced inZone A and 38 x 150 W lamps replaced in Zone B). A payback study indicated that the initialinvestment of installing the smart lampposts would be recovered in 4 to 7 years, as outlinedin Table 8, depending on the specification of the original lamppost being replaced294.

293 Shehedeh, N.H., Sustainable Street Lighting: A Guide too Efficient Public Street Lighting for Lebanon, A UNDP-CEDRO Publication,

December 2015294 Pardo-Bosch, F., Blanco, A., Sese, E., Ezcurra, F., Pujadas, P., Sustainable strategy for the implementation of energy efficient smart
public lighting in urban areas: case study in San Sebastian. "Sustainable cities and society", 2022, vol. 76, p. 103454:1-103454:12.

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Table 8. Lighting costs in 2 pilot schemes in San Sebastian (reproduced from 294)

Zone A
PSB

Zone B
LED

SMAR
T

PSA

LED

SMAR
T

Total cost investment per unit 0
(€)

450

550

0

450

550

Differences in investment vs CS

-450

-550

-450

-550

Annual cost of maintenance (€) 55

14

17

14

17

Savings
inmaintenance€/year/lamppost vs CS

41

38

41

38

Savings in maintenance in % vs
CS

75%

69%

75%

69%

Annual energy cost (4,100 149.24 51.73
hours year) (€)

37.35

51.73

37.35

Savings
in€/year/lamppost

97.51

111.89

24.39

38.77

65.34
%

74.97
%

32.04
%

50.93
%

Total cost of service (maint. + 204.24 65.73
energy) (€)

54.35

131.12 65.73

54.35

Savings
operation€/year/lamppost vs CS

138.51 148.69

65.39

76.77

Savings operation in % vs CS

68%

73%

50%

59%

PAYBACK (years)

3.25

3.7

6.88

7.16

NPV in 25 years (€)

2,288

2,536

1,306

1,554

energySavings in energy in %

55

76.12

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Case Study 6: Buenos Aires, Argentina (LMIC)
In 2013, the installation of a smart energy lighting system began in the city of Buenos Aires,
which was completed in 3 phases over a 3-year period. Initially, 11,000 LED lights were
installed on main avenues and streets, with an additional 80,000 installed on secondary
streets, upgrading 75% of the lighting in Buenos Aires. This resulted in a saving of 50% in
operational costs and a significant reduction in CO2 emissions295.
Case Study 7: Hamilton, Ontario (HIC)
Since 2009, the City of Hamilton has been involved in three LED streetlight pilot projects,
to investigate and verify the performance of different technologies. In 2015, over 10,000
high pressure sodium (HPS) streetlights were replaced with LEDs, including a pilot projectof 50 adaptive controls296. Ageing HPS systems and associated high maintenance costs aswell as the reduction in energy costs contributed to the motivation to upgrade to moreadvanced technology. Figure 21 outlines the outcomes of the pilot project, where the LED
lamps performed even better than projected, reducing energy consumption byapproximately 57%296.
10,300 LED Streetlights$5,500,000 Projected Costs$700,000/yr Projected Electricity Savings$800,000/yr Observed Electricity Savings$65,000/yr Maintenance Savings$3,800,000 IESO Incentive

3 year Projected Payback Period
1.25 year Observed Payback Period
Figure 21. Business Case for Hamilton LED conversion (reproduced from296)

295 Philips lighting website, Buenos Aires: Pioneering Future-Proof Connected Lighting,

CityTouch Buenos Aires – Philips lighting).

296 Lightsavers Canada, City of Hamilton’s LED Retrofit of High Wattage Streetlights, Canadian Urban Institute,(LightSaversCaseStudy.Hamilton.2017.07.18.pdf (squarespace.com)), 2017.

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Case Study 8: Québec, Canada (HIC)
In 2022 the Ministry of Transport in Québec began a 6-year project to replace High Pressure
Sodium lamps and some Mercury vapor lamps with LED lamps. The total project cost is
CAD$190 million which includes CAD$93 million for the reconstruction of the 600 V electric
system which is obsolete. To date, about 7,000 of the 80,000 road lamps have been
replaced. This modernisation programme is financed by government funding. Part of the
motivation behind the lighting overhaul was the difficulty in sourcing HPS bulbs, as they are
no long being produced by manufactures. Some public bodies decide to just replace thebulb with an LED “bulb”. In Québec, the decision was taken to upgrade the 600 V electricity
system and replace old lamps and bulbs with LED lamps.
In Québec, 3 types of lamps are being installed, each providing a different function to fulfil
the photometric requirements for the category of roadway lighting. There are different
costs associated with each type, as follows (cost includes lamp and LED bulb):•••

High-mast: CAD$2,200
Pole: CAD$1,200
Surface: CAD$1,200

In terms of operational costs, it is estimated that the scheme will reduce ongoing costs from
CAD$2.4 million to approximately CAD$1.8 million, a saving of CAD$0.6 million per year. It
is also estimated that annual energy costs will reduce from CAD$11.7 million to CAD$6.9
million upon completion of the scheme. Some lamps operate on a fixed price for power
while others have energy meters monitoring power and consumption. The cost of recycling
HPS and mercury bulbs was also highlighted. Since they contain hazardous materials,
appropriate methods of recycling must be adhered to, adding an additional cost to replaceeach bulb. Overall, the payback period for the scheme is relatively long (greater than 20
years). This is attributed to the low cost of energy in Québec and the extensive scope of thescheme including the reconstruction of the 600 V power grid. Currently, smart systems are
not included in the scheme, but the technology being supplied can be upgraded in the
future to increase functionality.
Case Study 9: Western Australia (HIC)
A case study examining the use of solar/wind powered lighting units in remote areas ofWestern Australia was described in the Positive Energy Roads Report297. A total of 7 units,each costing approximately AUD$18,000, were installed to reduce the likelihood of roadcrashes and other accidents. The total cost was approximately a third of the cost ofproviding conventional grid powered street lighting wherein a significant proportion of thecost is associated with providing the grid connection. Figure 22 shows the results of a

297 Lamb, M., Viner, H., Ramdas, V., McMahon, B., Positive Energy Roads - A PIARC Special Project, World Roads Association (PIARC),2019

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detailed evaluation of the many aspects of using solar/wind powered lighting in rural areasof Western Australia.

Figure 22. Evaluation of Solar/wind powered streetlights in Western Australia (from297)

Case Study 109: South Australia (HIC)
In 2019, the Department of Planning, Transport and Infrastructure South Australia carriedout an analysis of streetlighting replacement. The study examined the financial implicationsof replacing all low- and high-pressure sodium and mercury vapour lights with LED. Theenergy savings were valued at about AUD$693k per annum, with an associated capital costof AUD$10.2M, resulting in a payback period of 14.7 years. The analysis didn’t take accountof lights that may be close to their end of life and require replacement when they failregardless of the overall lighting replacement scheme. It was acknowledged that the
payback would have been shorter if this aspect had been considered in the analysis.
Based on this analysis, the decision was made to replace high pressure sodium or mercury
vapour light fittings with LED when they failed, rather than a complete overhaul of street
lighting in the region. Current energy savings from lamp replacement and the use of LED
instead of HPS on new installations is about AUD$78k per annum.
It was indicated that some local governments in South Australia had undertaken mass
replacement programs, but in these cases the payback was shorter as they were often
replacing less efficient light fittings. The energy saving from replacing the lighting systems
was greater, so the reduced ongoing cost of operating the lighting made it more attractive
on a cost basis.
Environmentally, there was no strong argument to implement a widescale replacement ofstreetlighting, as South Australia has a high percentage of renewable power, (a target of
100% renewable by 2030). Currently the grid emissions factor is 0.36 kgCO2e/kWh, which
is low compared to other states such as Queensland and Victoria with higher emissions
factors of 0.95 kgCO2e/kWh and 1.0 kgCO2e/kWh, respectively298.

298 National Greenhouse Accounts Factors – August 2021 (dcceew.gov.au)

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Case Study 11: Greenwich, UK (HIC)
A 6-year contract has begun in Greenwich to replace 20,000 streetlights and park lights
with LED lamps. It is forecast that this will save £1M per year in energy and maintenancecosts, saving 6,770,589 kWh per year and reducing energy consumption from street lighting
by 74% and CO2 emissions by 2,080 tonnes per year299.
Case Study 12: Leeds, UK (HIC)
In 2018, Leeds County Council approved a plan to invest £25.4M in new LED lighting,replacing 86,000 lights in the city with energy efficient alternatives. When the work iscomplete, it is estimated that the annual cost to run street lighting will be reduced by £3.4M(from current yearly spend of £4.8M). It is also estimated that energy consumed by street
lighting will reduce by 62%, equivalent to 7,050 tonnes of carbon savings. The initiative
includes a smart system to control the system remotely in real time to enhance
efficiency300.
Case Study 13: Wales, UK (HIC)In Wales, the Department of Transport borrowed £4M for LED lighting replacement
through the Green Growth Fund which provides funding for public sector projects that
support the Welsh Government’s energy efficiency strategy. In 2020, the conversion to LED
lamps was about 60% complete301. From analysis of the ongoing data of the effects of LED
lighting replacement, some limitations have been identified. The data indicates thatconversion to LEDs on motorways does not produce carbon savings, as higher lumen bulbs
are required to provide the level of lighting and dispersion required. Low pressure sodium
can be more efficient in this scenario, but bulbs may require replacement more regularly.
Another challenge was related to surrounding infrastructure and replacement of parts.
Some controllers are on their third generation because the electronics driving the LEDs are
failing. The investigation concluded that, in many cases, for LEDs to be an effective
sustainable alternative, the infrastructure behind them also needs improving.
In relation to Smart Systems, some savings were observed but they were less than
expected. Smart Systems demonstrated better efficiency at highway level but were not as
effective for local authorities using lower intensity lighting. An ongoing challenge is the
specialist knowledge that is often required to manage smart street lighting effectively.
When specialists leave or are not available, local engineers who are not trained in the area
are appointed to manage the system.

299 Ames, C., Greenwich borrows to invest in LED switch, Highways Magazine (Highways Magazine - Greenwich borrows to invest in LED

switch), 2021.
300 Highways Magazine, Leeds lights the way with £22.5m LED conversion, (Highways Magazine - Leeds lights the way with £22.5m LED
conversion), 2021.
301 State of the Nation 2020 Streetlighting Survey, UK Roads Liaison Group, CIHT (sotn-report.pdf (ciht.org.uk)).

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Case Study 14: UK (HIC)
In the UK, there are approximately 7.2 million streetlights, with nearly 4 million of those
LEDs (almost 55%). Of these LEDs, 30% are controlled by CMS (Smart Systems), 34% arepart dimmed at night and 3% are part of night operations, demonstrating various forms oflighting management across the UK. There are still 3.2 million lanterns that are yet to be
replaced. It is estimated that an investment of £755M could potentially save £6.8 billion ofelectricity cost and 5.1 M tonnes CO2 over the next 25 years.
8.3

CONSIDERATIONS FOR ROADS AUTHORITIESIn general, there is growing acceptance of the case for LEDs to reduce energy consumption
and carbon emissions (relative to traditional forms of lighting). However, the case studies
presented also highlight some of the challenges associated with the replacement of all
forms of street and highway lighting with LEDs. There is no “one size fits all” approach andthe optimum solution for each scenario is generally scheme and location dependent.
Having reviewed the outlined case studies and carried out interviews with variousorganisations, a list of points that should be considered when planning lighting for a newroad scheme or an overhaul of existing lighting are outlined in Table 9. The considerations
are split into headings but there is some crossover between points within each heading.
Table 9. Outline of considerations for planning lighting schemes

Category

Consideration Discussion

Technology

Current
systemplace

Is current technology old or relatively new? Consider
in the relative benefits of replacement with LEDs.
Options are to:
•
•
•
•
•

replace old bulbs with LEDs when replacement isrequiredchange all bulbs on the grid to LEDs
replace lamps and bulbs
upgrade outdated power infrastructure to support
extensive overhaul of lighting systemcomplete change to LEDs with smart system

If the current system is relatively new, it may notalways make economic sense to carry out a complete
overhaul of existing lighting and/or power
infrastructure.
Lighting
intensity
required

The levels of lighting required for a local road andmajor highway are different. It is crucial to consider
the type of lighting and intensity required (e.g., for a
multi-lane highway, light from high pressure sodium
bulbs may be more suitable than LED bulbs). TheCARBON NEUTRALITY OF THE ROAD SECTOR

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height of lighting poles also needs to be addressed toensure provision of adequate levels of dispersion.
Smartsystems

For retrofit of existing lighting, consider extent ofexisting infrastructure to be upgraded if changing to a
Smart System. For installation of LED lighting on new
schemes, Smart Systems are an option to provide
added flexibility which may lead to reduced ongoing
operating costs and carbon savings.

Dimmability

In the absence of Smart Systems, many modern LEDs
are supplied with programmable dimming facilities (atlittle or no extra cost).
A system with automatic sensors to change the lightintensity to suit local conditions would haveadvantages in countries and areas where the numberof daylight hours varies significantly through the year.

Economic

Location

Finance

The sources of finance and/or grants to provide
upfront capital cost (investment cost to install system)and ongoing maintenance/operational costs areimportant considerations.

Payback

Economically sound business case, including
evaluation of the period to obtain return on theinvestment are crucial. Some schemes can offer
stronger value for money when the technological andother factors outlined are considered.

MaintenanceLong maintenance contracts can be beneficial inmaintaining efficiency and energy/carbon savings.

Standalone
systems

Evidence has shown that stand alone systems can be
hugely beneficial when considering lighting systems inremote areas, and in some developing urban areas.

Solar/Wind
poweredConsider if this would be a preferential alternative togrid power in remote areas. In countries where solar
gain is abundant, solar lighting solutions can provide
drivers with a greater sense of security at night, andimprovement in safety for all road users. Availability ofsufficient wind or sunlight would need to be

CARBON NEUTRALITY OF THE ROAD SECTOR

confirmed/checked.
Solar
would
be
most
advantageous in areas that get sufficient consistentsunlight, with at least 10 hours of light per day insummer and winter, with latitudes between 0° and
33°N / 33°S from the equator302 (e.g., areas ofSingapore, Kenya, Ecuador, Columbia, Indonesia,
Nigeria, Australia, India)
Environmental Carbon
savings

Other

The potential carbon saving from switching to LEDs
can vary widely depending on various factors. The
source of power has the greatest impact. In a
country/region where the power is largely renewable,
the carbon savings from switching to LEDs would be
negligible compared to a grid where the power isgenerated using fossil fuels. Other factors to beconsidered are the type of lights being replaced andthe specifications of the LEDs required for the specificroad scheme.

Recyclability

HPS and mercury bulbs contain hazardous materials.
Appropriate methods of recycling must be adhered to,adding an additional cost to replacement strategies.

Biologicalimpacts

LEDs have greater lower-wavelength blue emissions
that potentially have increased likelihood of negative
biological impacts (e.g., suppression of melatonin
production which is crucial for many organisms)303.

Political
factors

In some cases, LED lighting is not viewed favourably by
the public304. This may influence policy decisions.

Skillset

Skills required to operate systems must be
acknowledged during and accounted for in thecontract to maintain long term savings from smart
systems.

302 Daylight hours by latitude - EverybodyWiki Bios & Wiki
303 Highways Magazine, October 2022, A LED Paradox (Highways Magazine (pagesuite-professional.co.uk)).
304 Led Lights Save Millions, but People Hate Them | Digital Trends

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9 ROAD CONSTRUCTION
Part B of this report summarises a range of technical solutions available to roadadministrations to reduce carbon emissions. This deep dive outlines the importance ofassessing specific sources of carbon emissions and explores some areas of road
construction in more detail, investigating the factors (costs, risks, etc.) that roadadministrations should consider in deciding whether these solutions are practical andappropriate in their own jurisdictions.
9.1

BASELINE LEVELS AND ONGOING STRATEGIES FOR CARBON REDUCTION

It is essential that roads authorities identify current sources of carbon emissions tounderstand where to prioritise reductions. For example, National Highways’ (UK) Net Zero
Plan305 quantifies the sources of carbon emissions from maintenance and construction, as
shown in Figure 23, which summed to a total of 734,000 tCO2e in 2020. This information
underpins the development of their strategy, which focusses on catalysing thedecarbonisation of the asphalt, cement and steel sectors, as well as adopting leanconstruction practices and principles of circular economy.

Figure 23. National Highways – sources of carbon emissions from construction and maintenance in 2020 (reproduced
from 305)

Similarly, a GHG emissions inventory published by the US National Asphalt Pavement
Association (NAPA)306 points to opportunities to reduce the cradle-to-gate emissions by up
to 24% relative to 2019 figures by adoption of measures including:•••

Increased use of recycled materials
Increased use of natural gas as a burner fuel
Reduction of aggregate moisture content to reduce burner fuel consumption

305 https://nationalhighways.co.uk/netzerohighways/
306 GHG emissions inventory for asphalt mix production in the United States. Current industry practices and opportunities to reduce

further emissions. National Asphalt Pavement Association Information SIP 106 (2022)

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Reduction of mix production temperatures through warm-mix technologies
Reduced electricity consumption through energy efficiency measures

Compiling emissions figures requires data from road administrations’ supply chain.
Feedback from the interviews during this project suggests industry is not always adequately
prepared to provide the data needed. In some cases, actions are being taken to engage
with the supply chain and build stronger requirements into contract specifications with theaim of acquiring data as well as achieving carbon reductions. Some parts of industry arealso being proactive and entering into voluntary arrangements. For example, NAPA outlines
information that asphalt producers should incorporate into tender bids for projects to earnpoints or credits under all major green construction programmes in the USA. Under the
Leadership in Energy and Environmental Design (LEED) scheme, this includes developing
Environmental Product Declarations (EPDs) (described below) to document reduced
impacts attributed to improved mix designs, disclose information regarding the raw
materials used or use of RAP, etc.307.
In tender evaluations, the use of EPDs should simplify the assessment of carbon emissions,as well as other sustainability impacts. The EPD presents information from a standardised
lifecycle assessment in a simplified way, enabling a comparison to be made between
products of the same type. The production of EPDs is described by ISO 14025308 and ISO
21930309. However, there are several challenges for obtaining robust EPDs, which roadadministrations should be aware of and take appropriate steps to control310:
•

•
•
•

Products can only be compared on a meaningful basis if the calculation methodology is
consistent. This is defined by Product Category Rules (PCR) which are established for eachproduct. However, not all products already have PCRs defined and global standardisationof PCRs is a challenge.
Use of generic, rather than site-specific data in the calculations can lead to inaccurate
declarations
A detailed, third-party, critical review is beneficial to ensure the validity of the resultspresented as well as consistency in the way PCRs are implemented
The cost of producing detailed LCA and EPD are not trivial and may be a particular burden
for small scale companies and industries

The Federal Highway Administration in the USA has recently announced a two-year
initiative in which technical assistance and staff training will be provided to facilitate thecompletion of lifecycle assessment and EPDs for 35 projects by 27 agencies311.

307 NAPA (2018) Sustainability in Practice: Asphalt pavements and LEED v4: credits and opportunities.

https://www.asphaltpavement.org/expertise/sustainability/sustainability-resources/leed-and-other-green-rating-systems
308 ISO 104025:2006 Environmental labels and declarations – Type III environmental declarations – Principles and procedures
309 309 ISO 21930:2017 Sustainability in buildings and civil engineering works – Core rules for environmental product declarations ofconstruction products and services
310 https://en.wikipedia.org/wiki/Environmental_Product_Declaration
311 311 FHWA (2022) FHWA climate challenge – quantifying emissions of sustainable pavements
https://www.fhwa.dot.gov/infrastructure/climatechallenge/projects/index.cfm

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OPTIMISED DESIGNTransport Infrastructure Ireland (TII) are re-evaluating the way in which road pavements
are designed, which will allow for greater efficiency in resource use and facilitate
innovation in the use of different materials312. This will improve on the empirical pavement
design models currently in use, which reference design curves that relate applied loading
to the required pavement depth, but do not take account of the physical properties of thematerials used or the environment in which they are to be constructed.
A new model, the Irish Analytic Pavement Design Model (IAPDM) enables these factors to
be considered. It evaluates specific material properties for pavement design, thereby
releasing the constraints on using alternative materials, and allowing options to reduce,reuse or repurpose materials to be considered. It also allows designs to be adjusted to takeaccount of field evidence of local materials which may perform to a higher level than isassumed in the current empirical design guidance. This thinking is central to circular
economy principles of obtaining the maximum value from material resources.
In operation, the tool collates data on site conditions and assesses how each layer of thepavement structure influences other layers and the pavement as a whole. Outputs are
expressed as tonnes of materials saved, tonnes of carbon saved and cost savings. In a casestudy, the IAPDM was applied to a 4 km segment of road where the capping layer had been
completed at the top of the foundation. Falling weight deflectometer readings showedsignificant variation in deflection response along the scheme length (Figure 24). The IAPDM
allows engineers to design for additional strength to improve on lower layers where this isneeded, and to save on these materials where sufficient strength can be verified.

Figure 24. Structural condition achieved for case study project (reproduced from312)

The optimised design allowed for an average saving of 30 mm in constructed depth
compared with the empirical design model. On a 11 km scheme with a 14 m wide

312 https://www.youtube.com/watch?v=y5eOAbx-LVE

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carriageway this translated to a saving of over 11,000 tonnes of material, €834,000 in costand 600,000 kgCO2. The analysis did not consider the additional savings in cost and carbon
that would occur due to the reduced transport of materials.
The ambition is to continue to develop the IAPDM, gaining confidence in acquired results,
with the aim to progress to a full mechanistic analysis of all pavement layers. It will be usedwithin an overall framework for circular economy that considers the lifecycle financial
value, lifecycle environmental value and societal value delivered by a planned scheme.

9.3

USE OF LOW CARBON CONCRETE

A key choice for construction of new road pavements is that of asphalt or concrete
construction. Historically, concrete pavements have been associated with a high carbon
cost for construction associated with the production of cement. Feedback during theinterviews with various roads authorities indicated that to achieve the long lifetimes thatare possible with a concrete pavement, a high-quality installation is critical. If this is notachieved, the result can instead be premature maintenance that is expensive both in termsof financial and carbon cost.
The Global Cement and Concrete Association (GCCA) recently published a Net Zero Road
map for 2050 and a report on progress one year on313. The Association’s member
companies operate worldwide and their affiliated organisations include a high proportionof LMICs. The road map targets a 20% reduction of CO2 per tonne of cement produced anda 25% reduction in CO2 per m3 of concrete used by 2030, compared with a 2020 baseline.
A Net Zero target is set for 2050. These targets are in the context of a background ofincreasing demand and are expected to be achieved through the following measures:
•
•
•
•
•

•
•

Efficiencies in design and construction (22%), i.e., optimised structural design, construction
site efficiencies and re-use / lifetime extension
Efficiency in concrete production (11%), i.e., optimised mix design and improvements tothe manufacturing process and quality control
Savings in cement and binders (9%), from substitution of Portland cement with alternatives
Savings in clinker production (11%), from thermal efficiency and use of alternative fuels
Carbon capture and utilisation or storage, CCUS (36%), with a goal of 10 fully operational
CCUS plants by 2030. Significant activity is reported, with over 35 pilot projects exploring a
range of different technologies across the world. (In the UK, the current cost of carbon
capture and storage is reported to be in the range US$50-70/tCO2 for a cement kiln, which
would increase cement production costs by about 30-60%314.)
Decarbonisation of electricity at cement plants and in concrete production (5%)
CO2 sink (6%) through the natural process of recarbonation (atmospheric CO2 taken up by
the surface of concrete particles)

313 https://gccassociation.org/wp-content/uploads/2022/10/7286_GCCA_RoadmapOneYearOn_Artwork_Screen_v3_lr.pdf
314 https://www.ice.org.uk/media/q12jkljj/low-car303bon-concrete-routemap.pdf

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The most recent data, from 2020, shows a 22% reduction in net CO2 emissions per tonneof cementitious material produced, compared with a 1990 baseline. The progress report
describes 25 carbon reducing projects that are provided by GCCA members. They represent
diverse technical approaches and appear promising at a pilot scale. However, little usable
data is provided to judge their progress or potential for scale up.
The Low Carbon Concrete Group of the Institute of Civil Engineers (UK) has recommended
a labelling scheme so that ‘low carbon concrete’ can be identified for each strength class314.
Data from more than 600 recent UK mixes were collated and compared with data from fourlarge producers to derive rating bands representative of the embodied carbon per m3 forlifecycle stages A1-A3 (cradle to batching plant for ready mix concrete, or cradle to mouldfor precast concrete). Taking C35/40 concrete as an example, interpolating the presented
curves suggests approximate benchmark ratings shown in Table 10.
Table 10. Estimated ranges for C32/40 concrete (reproduced from 314)

Embodied carbon

RatingCorresponds to (percentile of benchmarked
concretes in this strength class)

0-77

A++

Lower than benchmarked concretes

77-137A+

0-5%

137-190A

5-20%

190-230B

20-40%

230-263

C

40-60%

263-303D

60-80%

303-356E

80-95%

356-416F

90-100%>416

GHigher than benchmarked concretes(kg CO2 / m3)

Loijos makes a comprehensive assessment of the carbon emissions for the full lifecycle ofa concrete pavement, for 12 typical pavement structures in the US315. The necessity toconsider all stages of the lifecycle is highlighted to get an accurate perspective, whereas
many studies published in the literature omit one or more stages. In this study, the author
examines a 40-year lifecycle analysis that includes construction, rehabilitation carried out

315 Loijos A (2011) Life cycle assessment of concrete pavements: impacts and opportunities. Massachusetts Institute of Technology.

https://dspace.mit.edu/handle/1721.1/65431

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at year 20 and 30, and disposal and recycling at year 40. The following elements arequantified:
•
•
•
•
•

Materials extraction and production (cement production, aggregate crushing, mix water
processing, steel reinforcement production, fly ash production)
Pavement construction (concrete mixing, onsite equipment operation)
Pavement rehabilitation (diamond grinding, slab replacement)
Use (albedo, carbonation, fuel consumed due to roughness, lane closure, lighting)End of life recycling and disposal (steel recycling, pavement demolition, jaw crushing forrecycling concrete, landfilling)

Since the results may be influenced significantly by the type of pavement structure, Loijos
analysed the designs for 12 representative pavement structures, which were determinedfrom the typical traffic flow, road width, and required level of performance for different
road types. Table shows the calculated lifecycle carbon emissions per km of new concrete
pavement, which suggests there is an order of magnitude difference between the carbon
intensity of the most and least demanding applications. (For this reason, to assess theefficiency of resource use, indicators should consider the intensity of use that is supportedby the resources committed to each application, e.g. the traffic carried during a pavement’s
lifetime.)
Table 11. Lifecycle GHG emissions per km of new concrete pavement (using data from315)

Rural road types

t CO2e*Urban road types

t CO2e*Interstates

3,690

Interstates

6,190

1,280

Other
freewaysexpressways/ 3,980

Minor arterials

1,140

Other principal arterials

2,360

Major collectors

730

Minor arterials

1,290

Minor collectors

510Collectors

940

Local roads

320

Local roads

520

Other
arterials

principal*From data given in Appendix 4 of the reference cited

The contributions to totals above are given in Figure 25. In the figure, the carbonation
contribution is shown as negative (this refers to the effect of atmospheric carbon dioxide
becoming bound to the concrete surface and is affected by maintenance strategies andhow the concrete is disposed of at the end of life). The single largest contribution, for allroad types, is from cement production, which ranges from 51% of the total emissions on
urban interstates to 85% on rural local roads. The results are most sensitive to variation in
the width and depth of the concrete pavement, and by the carbonation rate and % cement
used in the mix.

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Figure 25. Lifecycle CO2e per 1 km, by road type and component (using data provided in315)

The impact of four carbon reduction strategies were examined:
•

•

•
•

•

Reducing cement content by substitution with up to 30% fly ash. This is also believed toincrease the rate of carbonation. Other strategies for reducing cement content were noted
but not analysed. Furthermore, potential effects on the durability of the pavement were
not considered.
Whitening the pavement though selection of the aggregate and sand to reduce albedo. This
provides benefits by increasing the reflection of sunlight back out of the Earth’s atmosphereand by reducing the requirement for pavement lighting.
Increasing carbonation through end-of-life management. If concrete is crushed at the endof life, the surface area available for carbonation increases. .
Reducing fuel consumption due to pavement roughness. The model includes an additional
rehabilitation at year 10 to improve the surface characteristics, with additional depth ofpavement at construction to allow for this grinding.
A combination of these strategies seems to offer the potential to reduce lifecycle carbon
emissions by well over 50%. The most effective strategy was dependent on the road type:on interstates, the end-of-life carbonation was found to be the most effective strategy
whereas fly ash substitution was found to be slightly more beneficial on roads with lessthan 20,000 vehicles/day. Although carbonation was reported in this paper to be the mosteffective strategy, the benefit will not start to be felt until many years in the future, which
does not reflect the pressing need for reduction.

On rural local roads, reducing albedo is effective, since the structure is relatively thin, i.e.
with a high surface area to achieve the beneficial effects, for its volume. However,additional transport distances to obtain white materials need to be factored into thisbenefit, and this is affected by the carbon intensity of the transport mode used. For
additional pavement rehabilitation to reduce roughness, the benefits are greatest on roads
carrying high traffic, with an AADT of approximately 2,500 calculated as the point at whichCARBON NEUTRALITY OF THE ROAD SECTOR

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the carbon saved outweighs the carbon cost of the additional treatment and slightly deeper
construction.
9.4

USE OF RECLAIMED ASPHALT

Reuse of reclaimed asphalt has both financial and sustainability benefits. The National
Asphalt Pavement Association (NAPA) in the US report a growing number of States using
greater proportions of reclaimed asphalt pavement (RAP) in hot mix and warm mix asphalt
pavements316. Asphalt mixtures containing recycled materials should meet the samerequirements as mixtures with all virgin materials and perform as well or better. NAPA citea study analysing Long-Term Pavement Performance data from 16 US states and two
Canadian provinces which show that overlays with at least 30 % RAP performed equally tooverlays using virgin mixtures. Similarly, test sections containing 50% RAP on a test trackoutperformed comparative test sections with all virgin materials, in all performancemeasures.
Figure 26 plots a subset of NAPA data that estimates the proportion of RAP, on average, in
HMA / WMA. By 2020, it was estimated that at least 20% RAP was used, on average, inmore than half of the States where data were obtained.

Figure 26. Number of States with Estimated RAP% in the ranges shown (reproduced from316)

NAPA estimated the GHG emissions reduction from the use of RAP, based on a national
total of 87.0 million tons of RAP:•••

2.51 million tonnes CO2e through the avoidance of virgin binder, equivalent to the 5%binder present in RAP
0.35 million tonnes CO2e through the avoidance of virgin aggregate, equivalent to the 95%
binder aggregate present in RAP
0.45 million tonnes CO2e through the avoidance of transport, assuming average haulage
distances and emissions factors for transportation via medium and heavy-duty trucks

316 Asphalt pavement industry survey on recycled materials and warm-mix asphalt usage 2020. National Asphalt Pavement Association

Information Series 138, www.asphaltpavement.org

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•
•
•

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Emissions from the transport and processing of RAP were ignored as being associated withthe end-of-life phase of the previous pavement
0.11 tonnes CO2e additional associated with processing of RAP
0.88 tonnes CO2e additional associated with transport of RAP over a 50-mile haul distanceto the asphalt plant
Emissions from the use of softer binders and recycling agents were ignored owing to a lackof data (which means that the full impacts were not quantified)

The total corresponds to a 2.32 million tonnes CO2e avoided, for 87.0 million tons RAP
utilised in asphalt mixtures, i.e. 27.1 kt CO2e / t RAP. The corresponding cost savings were
estimated as $2.955 bn in total, i.e. $34.5 M / t RAP, for savings in aggregate and binder.
Further additional cost savings of $58.6 / t RAP were estimated from the avoidance oflandfill fees.
While the use of RAP can produce high performing asphalt, with reduced carbon emissions,
NAPA points to the need for good practice to produce high quality results317:
•
•
•
•
•
•

Managing the reclaiming process to avoid contamination with dirt or other construction
materials
Managing RAP stockpiles to avoid segregation, average out variations in the materials
received, avoid compaction of the stockpiles and minimise moisture content
Control of processing to obtain a uniform material that matches the need for the mix
design, while avoiding the production of excessive fines
Using appropriate methods of sampling to accurately characterise the stockpile for testing
Carrying out testing to determine the asphalt binder content, gradation of the aggregate,bulk specific gravity and aggregate properties
Implementing various measures in mix production needed to accommodate RAP

Their guidance also covers management of recycled asphalt shingles and further advice isproduced on mix design guidelines for mixtures incorporating RAP318.
9.5

CASE STUDIES ON RECYCLED ASPHALT

In a 2010 case study of a 4.7 km section of State Highway in Wisconsin, USA, a lifecycle
analysis compared a conventional pavement design with an alternative design
incorporating recycled materials319. The alternative design used 305 mm recycled
pavement material stabilized with fly ash as base course on top of a sub-base of 760 mm
foundry sand. These layers replaced equivalent thicknesses of conventional crushed
aggregate and subbase, respectively. Both designs were topped with 160 mm hot mix
asphalt (HMA).

317 Best practices for RAP and RAS Management. National Asphalt Pavement Association Quality Improvement Series 129

www.asphaltpavement.org
318 Designing HMA mixtures with high RAP content. National Asphalt Pavement Association Quality Improvement Series 124
www.asphaltpavement.org
319 Lee, Jin & Edil, Tuncer & Tinjum, James & Benson, Craig. (2010). Quantitative Assessment of Environmental and Economic Benefitsof Recycled Materials in Highway Construction. Transportation Research Record: Journal of the Transportation Research Board. 2158.
138-142. 10.3141/2158-17

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The lifecycle analysis modelled the deterioration of IRI (International Roughness Index),
with a predicted design life of 29 years for the conventional materials and 32 years for therecycled material, owing to its expected superior properties. With a 50-year analysis period,
this resulted in one rehabilitation of the pavement in both cases.
The authors’ analysis of material production, transportation and construction is shown in
Table 12. In both cases, the HMA component is reported to be the dominant contributor
to all four of the environmental indicators, so the overall benefit of using recycled materials
is modest. Nevertheless, the analysis predicts an overall 20% reduction in CO2e, most ofwhich occurs from reduced emissions during material production. Substantial energy
savings are also predicted, although the study does not provide carbon reductions
associated with the reduction in energy requirements.
Table 12. LCA predictions using conventional and recycled materials (reproduced from 319)

Conventional materials

Recycled materials

ChangeMaterial
productionTransportationConst
ructionMaterial
ProductionTransportationConstru (%)
ction

CO2 (Mg*)

3,630

323

111

3,028

163

54

-20

Energy(GJ*)

66,680

4,318

1,476

58,023

2,187

723

-16

RCRA
hazardous
waste
(Mg*)

629

31

9

611

16

4

-6

Water (L)17,185735

144

15,637

372

70

-11

*GJ = gigajoules ; Mg = megagrams (i.e. tonnes)
From a cost perspective, a 21% saving is predicted in both Agency cost and user cost (CARBON NEUTRALITY OF THE ROAD SECTOR

Table 13), which includes the avoidance of landfill tipping fees of $40/Mg.

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Table 13. Lifecycle costs for pavement designs using conventional and recycled materials (reproduced from 319)

Category
Agency($)

Reference

Alternative

Savingcosts 9,044,570

7,107,230

1,937,340 (21%)

User cost ($)

10,5708,380

2,190 (21%)

Total cost ($)

9,055,140

7,115,610

1,939,530 (21%)

Qiao et al.320 cite several other studies that predict cost savings as a result of using recycledasphalt pavements (RAP), including when the progression of rutting and cracking is
considered in addition to roughness. Their study goes further, considering the implicationsof local weather conditions and future climate trends up to 2040.
The study focusses on financial cost to the road administration. Carbon savings are notconsidered explicitly. However, many of the savings in cost are likely to be associated withsavings in carbon, as seen from the above studies, and this methodology could be adapted
to quantify carbon benefits.
A 22 km length of the I-95 interstate highway in New Hampshire, USA, was selected as acase study. It has an annual average daily traffic flow of 88,000, with 10% heavy vehicles.
Dynamic modulus testing from similar structures was carried out to establish the properties
of HMA containing 40% RAP and HMA using virgin aggregate, over a range of temperatures.
These data were used to improve the prediction of future pavement performance,
depending on the temperature regime it is exposed to. Climate models were used to
predict future, local trends in temperature and rainfall under a moderate scenario of global
warming. For the study location, these models predicted a reduction in extreme cold
conditions, increase in extreme hot condition and increase in rainfall in future years.
The 20-year lifecycle analysis modelled roughness, rutting, thermal cracking and fatigue
cracking, with appropriate maintenance interventions when triggered by pre-set
thresholds. All lifecycle stages were modelled: material production, transport,
construction, maintenance, use (i.e. road user costs) and salvage. The following
maintenance scenarios were predicted for a standard structure (150 mm asphalt concrete
over 710 mm granular base and 200 mm sub-base) for the two different materials:••

For the virgin HMA, an overlay was triggered in year 6 and year 15 as a result of rutting
For the HMA with 40% RAP, local crack sealing was triggered in year 3 as a result of thermal
cracking, and an overlay was triggered in year 8 as a result of rutting

320 Qiao Y, Dave E, Parry T, Valle O, Mi L. Ni G, Yuan Z and Zhu Y Life cycle cost analysis of reclaimed asphalt pavement (RAP) under

future climate. Sustainability 2019, 11, 5414, doi:10.3390/su11195414

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The difference between the maintenance scenarios results from the higher stiffness of the
HMA with 40% RA, which accelerates the development of thermal cracks but reduces the
progression of rutting. This translates to a significant reduction of lifecycle cost for the
maintenance phase, compared with HMA with virgin materials (Figure 27), despite theadditional treatment for thermal cracking. Reductions are also observed for theconstruction and transportation stages. Collectively these three stages make up the
majority of costs to the road administration, which are predicted to be 18% lower for HMA
with 40% RAP than for the virgin materials. However, when the use phase is considered,this translates to a modest 2% reduction since, for both material types, the overall cost isdominated by road user fuel consumption.

Figure 27. Relative lifecycle cost for HMA with 40% RA, compared with virgin material (reproduced from320)

Similar findings were observed from the other, stronger pavement structures considered:in all cases the drivers for maintenance were predicted to be rutting (for the virgin HMA)
and thermal cracking (for the HMA incorporating 40% RAP). In both cases, the stronger
structures were predicted to be more resistant to deterioration. This reduces the differencein the cost to the road administration between the two materials and also results in an
overall cost saving because the higher construction costs are more than offset by the saving
in maintenance costs from the stronger structures.

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USE OF OTHER SECONDARY MATERIALS IN ROAD CONSTRUCTION

A quarter of the companies responding to the NAPA survey in 2020 316 reported use ofadditional recycled materials in asphalt mixtures. The data are summarized in Table 14.
Table 14. Summary of the use of additional recycled materials, reported to NAPA for 2020 (reproduced from 316)

Asphalt mixture
reported to be
producedwiththismaterial(tons)

NumberofQuantityofStates in whichmaterial
this material is Reference
reported to bereported
used (tons)

1,343,406

19,025 10

10

Table 19

Steel Slag

3,850,456

643,484

10

Table 20

Blast
Slag

121,241

666,873

6

Table 20Recycled Fibres

2,249,354

8,748

22

Table 21

Coal
Combustion
Products

435,492

13,883

7

Table 22

Other recycled
81,000materials*

6,005

4

Table 23

Recycled
RubberTyre

Furnace*Comprising, in 2020: blasting sand, marble production dust, plant start-up waste andrecycled polyethylene; crushed concrete aggregates were also reported in previous years.
Liu et al.321 reviewed the potential for reducing carbon emissions, stated in literature, assummarised below.

321 Liu N, Wang Y, Bai Q, Liu Y, Wang P, Xue S, Yu Q and Li Q. Road life-cycle carbon dioxide emissions and emission reduction

technologies: a review. J. Traffic and Transportation Eng. (2022); 9 (4) p532-555

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Table 15. Summary of the potential for carbon reduction from use of recycled materials (from Liu et al.)Recycled
material
RAP

CrumbrubberLocation

Key finding

USA

Reduction up to 12.4% with increased RAP content in asphalt
binder

Italy

Reduction of 6.8% for RAP with HMA

Italy

Reduction of 48.3% with RAP and lime stabilization for an
embankment; 21.2% for RAP only or 11.0% for lime stabilization
only

USA

Carbon emissions of asphalt rubber are higher than HMA but
lower than Portland cement mixtures

China

Reduction of 17.1% compared with styrene-butadiene-styrene
modified asphalt

Italy

Reduction of 36-44% for asphalt with 18% crumb rubber using
wet technology, compared to standard mixture

IndustryUSA
wastes &byproducts
India

Reduction of 29.6% from partial substitution of Portland
cement with fly ash

Steel

Reduction of 5%-27% from use of recycled steel

SwedenLimestone and brick dust < stone dust mixes < glass powder andconcrete dust

A comprehensive review of the use of tyre rubber in asphalt pavements is provided by
Presti322. Different production processes are possible; some are relatively complex andrequire specialist plant with high set-up costs. However, extensive development has takenplace and asphalt incorporating tyre rubber has been widely used, including in the USA(Arizona, California, Texas and Florida), South Africa, Australia and Europe, with investment
reported in Taiwan, China, Brazil and Sudan. The benefits can include improved durability,
resistance to cracking and reduced temperature susceptibility. One lifecycle study reportedby Presti shows a 46% reduction in maintenance costs and a 33% reduction in user costs
compared with conventional asphalt, over a 25-year life. However, Presti notes otherstudies that suggest they are not cost effective in all situations. Furthermore, there isextensive evidence of the performance level of asphalt produced by well-established

322 Presti D Recycled tyre rubber modified bitumen for road asphalt mixtures: a literature review. Construction and building materials

49 (2013) p 863-881

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methods, whereas this is not the case for newer methods. There are some concerns overthe use of tyre rubber in asphalt pavements. Production of fumes has been cited as an
issue, although this is significantly reduced by adoption of warm mix methods. The
recyclability of the rubberized asphalt at the end of life also needs to be considered,although there are examples where this has been achieved successfully.
9.7

CONSIDERATIONS FOR ROADS AUTHORITIESTransparency of performance is essential for effective decision making. By baselining
existing carbon emissions and identifying the major sources of emissions, an appropriate
reduction strategy can be developed.
For a robust approach to assessing options, the scenarios evaluated should take account oflocal conditions (e.g. for transport distances and the efficiency of local plant). All phases ofthe lifecycle should be evaluated (many published studies omit one or more stages); acompetent analysis will declare the stages considered in relation to established standards
for lifecycle analysis. The system boundaries should also be studied carefully, in case anapparent reduction in emissions in one area results in displacing the burden to a different
part of the process. This has been found to be key across all strategies for carbon neutrality.
The analysis requires estimation and, as such, sensitivity analysis is essential to identify
critical influences and the assess the uncertainties associated with them.
Existing design strategies can be challenged to allow for greater resource efficiency. Thiscan take account of site conditions, properties of locally available materials, site-specifictraffic, etc., as well as the predicted environmental conditions considering climate
projections over the life of the pavement.
Engagement with industry stakeholders early in the project development stage can allow
ways to reduce carbon to be investigated, and drive motivation for further innovation.
Numerous different approaches to carbon reduction are being employed. In some cases,
e.g. use of reclaimed asphalt or cold-mix or warm-mix asphalt in place of hot-mix, thetechnical and financial cases have already been established. In other cases, or to achieve
greater reductions, further innovation will be needed and here road authorities have an
important role in establishing pilot projects and sharing lessons learned.
Irrespective of the design option selected, requiring suppliers to produce information on
the carbon (and other) impacts will drive a focus on reduction. Environmental productdeclarations, rating systems or other standardised approaches should be adopted toprovide a consistent means to rank proposals.

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PART D – Conclusions and Recommendations
10 GAP ANALYSISThe number of examples reported relating to different strategies adopted by NRAs areshown in Figure 28. The largest segment is for low carbon design and construction, partly
reflecting the deeper analysis of road construction in Part C of this report. This topic
includes sources on the use of recycled asphalt, use of other secondary materials, warmmix asphalt and reducing the carbon intensity of concrete through the use of alternative
cement binders. For this topic, as well as for road maintenance and life extension, thequality of the evidence on the degree of carbon reduction is relatively high, with around
40% of sources rated as providing reliable, quantitative information.
The second largest segment is for influencing choices of road users, with 16 examples, split
between transfer to active travel and public transport. 15 examples were identified ofoperations on the road network, primarily the opportunities for LED lighting, and 13 fordecarbonising vehicles and fuels.
A smaller number of examples was found for low carbon options for construction plant,
procurement and carbon offsetting, reflecting the early stages of development for
strategies in these areas. Only three examples were identified of the carbon impacts ofroad maintenance and life extension, probably reflecting that there is insufficientawareness of the carbon impact of traditional asset management decisions.
For topic areas other than low carbon design and construction, and road maintenance andlife extension, the percentage of sources rated as providing reliable, quantitative
information was lower, always below 20% and, on average only 10%. As it stands, thismakes it difficult for road authorities to assess the best strategies to achieve their goals.
Furthermore, it should be noted that, even where they are quantified, the benefits
achieved in one situation may not match those achieved elsewhere, with different
circumstances (so it will be important for road authorities to either conduct their own
analyses or assess the parallels of any study with their own situation).

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Figure 28. Summary of the strategies reviewed

The strategies reviewed were classified depending on how far they have progressed to full
implementation, and this is summarised by topic in Figure 29. Extent to which the strategies
reviewed have been adopted. For decarbonisation of vehicles and fuels, the examples showthat they have largely progressed beyond ambition, to trial and progressive rollout. This isalso the case for operations on the road network (dominated by LED lighting), whereas theexamples for influencing road users are less well advanced, mainly at the level of research
and ambition.
Surprisingly, for low carbon design and construction, for which the quality of evidence ishigh, few sources provided data relating to extensive rollout; the quantification of carbon
benefits seems largely to remain at a research or theoretical stage. This was also the casefor road maintenance and life extension. This suggests that better quantification of the
carbon impacts of construction and maintenance is needed, as a matter of routine, to allow
these assessments to be made.
There are examples of low carbon construction plant progressing to limited rollout, but thishas yet to progress into widespread use. Initiatives in procurement, by their nature, areunlikely to involve a research stage. Finally, for carbon offsetting, there are several
initiatives underway but the quality of evidence of outcomes achieved from these schemes
was particularly low, with none of the sources rated as providing reliable, quantified
evidence of the carbon benefits.

CARBON NEUTRALITY OF THE ROAD SECTOR

Figure 29. Extent to which the strategies reviewed have been adopted

A breakdown of the origin of the examples reviewed is given in

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Table 16, for geographical region and in Table 17 for the country type. The responses are
dominated by Europe and Central Asia, specifically by the European Union and United
Kingdom, followed by East Asia and Pacific, which includes a broad range of countries:
Australia, China, Hong Kong, Indonesia, Japan, Republic of Korea and Vietnam. 30% of
examples are from LMIC countries.

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Table 16. Number of examples by region
RegionNumber of examples

East Asia and Pacific10Europe and Central Asia

33

Latin America and the Caribbean

2

Middle East and North Africa

2

North America

18South Asia

2

Sub-Saharan Africa

5

Not stated / various

25

Total

97
Table 17. Number of examples by country type

LMIC?

Number of examples

Yes

16

No

56

Not stated / various

25

Total

97

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11 SUMMARY OF TECHNICAL SOLUTIONS AND POTENTIAL
CARBON SAVINGS
It is very difficult, if not impossible to determine the potential carbon savings that could bemade globally, as the situation of each NRA and options available will be different, forexample, budget, ambition, technical capability, not to mention areas beyond the remit ofNRAs, such as wider governmental targets on achieving net zero and the mix of fuels used
to power the electricity grid (for the powering of electric vehicles and/or production ofgreen hydrogen).
Nonetheless, a summary of technical solutions identified and estimates of the levels ofsavings by adopting various options is presented below.
11.1 CONSTRUCTION AND MAINTENANCE OF ROAD INFRASTRUCTURE
Need for road construction
A pause and review approach such as that set out by the Welsh Government can allow
different priorities to be established for road investment, with greater emphasis on
reduction of carbon emissions, and shift to active travel and public transport.
Road maintenance and life extension
A pavement that is well maintained, smooth and in good condition will also lead to lower
emissions from vehicles using the road. Regular maintenance and life extension of roadinfrastructure can form part of CO2 saving strategies.
•

Road maintenance practices and policies vary throughout the world, so it is difficult todetermine the global CO2 savings from more efficient road maintenance or life extension.
To make a crude approximation, given the length of paved roads worldwide isapproximately 12.7 million km and an assumption that 10% of roads are maintained
annually, extrapolating figures presented in Section 3.2 indicates a potential saving of
between 25-28 MtCO2 annually from choosing maintenance practices such as chip seal andcrack seal over thin overlay. These figures are purely indicative in the absence of full Life
Cycle Analysis but give a very tentative estimation of the scale of saving that could
potentially be achieved from using less carbon intensive methods.

Low carbon construction
•
•

•
•
•

Advances are being made in carbon neutral construction and operation practices, as
follows:
The A590 project in the UK demonstrated how significant carbon reduction can be achieved
across three main areas of carriageway construction; materials reduction and reuse, energy
reduction and transportation efficiencies
Early consultant and early contractor engagement is critical
Various case studies highlighted the importance of both optimising the design life andsetting targets for environmental performance early in the project
Structural Health Monitoring can be used to determine the condition of bridges reaching
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The production of cement is very carbon intensive, with 0.59 tCO2 generated for each tonneof cement produced in 2021. The International Energy Agency (IAE) published a roadmap
to reach net zero by 2050, outlining methods to reduce carbon emissions associated withcement production323. The IAE also reports an earlier target to reduce emissions to 0.43
tCO2 generated for each tonne of cement produced by 2030324. It is expected that carbon
reduction can be achieved using biothermal and renewable energy to produce cement andby reducing clinker to cement ratio using clinker substitutes. If global targets are met,
assuming a linear progression each year between 2022 and 2030, an ongoing increased
reduction of about 7.5 MtCO2 could be achieved annually in the road construction sector(assuming 10% of cement is used in the road construction sector). It is noted that thesetargets are not currently being met, so it is unlikely savings on this magnitude will beachieved.
Regarding concrete design and Secondary Cementitious Materials (SCM), assuming that 5%of new roads constructed annually will be concrete (taking account of pavements andhighway structures etc.), using an additional 10% SCM in the concrete mixes could result in
global reductions of between 0.8 MtCO2 and 3.8 MtCO2 annually.

Low rolling resistance pavements

Construction of smooth and stiff pavements can reduce transport emissions, by improving
fuel efficiency of the vehicles driving on them. When compared to conventional pavement
construction, the CO 2 savings associated with low rolling resistance pavements could be
between 6,000 and 12,000 tonnes, per 1 km of high traffic, 4-lane carriageway during a 15year life.
Circular economy and resource efficiency
By transforming how materials are used and by optimising utility, circular economy
approaches have the potential to make a significant contribution to completing thedecarbonisation of the transport sector.
•••

Learning from previous projects that have adopted circular approaches, it is essential toconsider circularity in the early stages of the scheme
Ongoing monitoring and evaluation is important to achieve long term goals and to influence
future work
A collaborative approach between procurers and suppliers is essential

Potential carbon savings are difficult to estimate as it has not been implemented widely, sosavings are very scheme specific currently. It also depends on the nature of the solution
being developed, the construction material and method and other scheme objectives suchas net biodiversity gain. On an 11km scheme in Ireland, savings of over €800,000 and 600t
CO2 were achieved.
Low carbon materials

323 Net Zero by 2050 - A Roadmap for the Global Energy Sector (windows.net)
324 Cement – Analysis - IEA

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Advances in material technology now offer the potential to use low (or lower) carbon
alternatives to conventional construction materials.
•

•
•
•
•

Warm mix or cold mix asphalt materials are tried and tested alternatives to hot mix and arealso, in some cases, more suitable to local conditions. Carbon savings could be in the orderof 8 to 16 tonnes from using warm mix asphalt in place of hot mix asphalt per 1 km of 4
lane carriageway
Secondary cementitious materials can be used as clinker/cement alternatives to reduce theCO2 emissions associated with the production of concrete.
Optimization of concrete mix design can lead to lower cement content in concrete paving
mixes and reduced CO2 emissions
Recycled concrete can be used as coarse aggregate in concrete mix designs to reduce
environmental impacts
Using high performance concrete can have the effect of reducing net cement quantity
required in construction of concrete structures as well as having the potential to increase
durability and reduce CO2 emissions associated with maintenance and rehabilitation overthe lifespan of the structure

Decarbonisation of construction plant and construction operations•

Road maintenance activities alone may emit 8 million tonnes of CO2 per year. There is thepotential to save a significant proportion (potentially up to 50% for some sites andoperations) through job site optimisation, machine optimisation and machine control.
There is the potential for the remainder to be powered by electricity or hydrogen.

There are various options to reduce fuel use from construction plant, including machine
control to improve efficiency of operation, use of GPS to ensure, e.g. correct compaction
through to fully automated plant in some use cases (e.g. mines and quarries) operatingwith optimum efficiency. In terms of alternative power for construction plant to replace
diesel, the size and use cases of machines influences the choices available.
•

•

•

•

Many smaller items of plant, such as mini diggers, access platforms and small dump trucks
are now offered in battery electric variants, with an 8+ hour operating window andovernight charging
Whilst there are some examples of very large battery vehicles, in general it is consideredthat hydrogen is the way forward with both direct burn of hydrogen trialled and hydrogenfuel cell operation for large plant. There have been some concerns about the robustness ofhydrogen fuel cells in challenging construction environments
Biodiesel is another potential option, though there are concerns regarding the use of
agricultural land to grow fuel crops, whilst there remain exhaust emissions. There aredemonstrations of advanced biofuels manufactured from non-edible sources such as
woody crops, wood chips and agricultural waste such as husks and stems. This does notcompete with food production but has not yet been operated on an industrial scale
The use of solar powered lighting solutions is now becoming more common to replace
diesel generators. Apart from the benefit of zero carbon operation, there are no exhaustemissions, zero noise and operational improvements through avoiding the requirement forrefuelling with diesel. Some claim to be able to operate year-round, even when there are
16 hours of darkness, whilst there are solar hybrid options with a diesel back up

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•

•
•

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Depending on the level of use and exact size of the lighting tower, it could be possible tosave 5 tonnes of CO2 per year, per unit by switching to either solar power, or greenhydrogen.
Estimating the potential savings achievable by replacing diesel generators with solar power
or green hydrogen is far more difficult due to the large variations in the size andapplications. However, based on reasonable assumptions of mid-size generators, thepotential savings could be in the order of millions of tonnes per year
The use of hydrogen fuel cell powered lighting and site power has also been trialled on
construction projects and are increasingly in use in other sectors (e.g. film and tv).
NRAs should investigate what lighting towers and generators are used in their organisation
and by their supply chain and look to a rolling programme of replacement where possible.
Efforts to stimulate the market for green hydrogen production would need to be made to
replace diesel in large generators.

11.2 DECARBONISATION OF ROAD USER VEHICLES••Road vehicles emitted around 5.6 Gt of carbon in 2020, the largest of all carbon sources inroads. Theoretically, all of this could be provided by carbon neutral means, through electricvehicles being charged with electricity produced by renewables, or green hydrogenproduced by electrolysis of water, powered by renewable energy. There may be roles forbiofuels that don’t compete with food production or niche applications for synthetic fuels.
Emissions generated from vehicles using the road, represent the largest source of carbon,
but also the one on which national road administrations have the least control.

Road administrations can support low emission vehicles, through for example, theprovision of electric vehicle charging points, but other government bodies have the control
over fuel standards, public transport and energy policy.
••

Most fuels sold in Europe and other regions have a small percentage of biofuel bended
within them.
For light vehicles such as cars and vans, battery power has taken the significant market
share, with 3 million vehicles sold in 2020, compared to only 26,000 hydrogen vehicles, with
only two production models available.

There are also significant numbers of electric buses in use, the majority of which are in
China. Hydrogen could be a viable option for buses too, especially in cities with many hills
and either cold or hot temperature extremes, which makes battery power less efficient.
••

For heavy goods vehicles, whilst there have been trials of battery powered units, which
could potentially have sufficient range, hydrogen or direct electric power seem to be thefrontrunners at this stage. One reason that hydrogen has not taken off for light vehicles islack of fuelling infrastructure. This should be less of an issue for heavy goods vehicles asfuelling facilities can be installed at depots. For electric power, for example throughcatenary wires, this would require road administration involvement at some level.
To achieve this would require vision, intra- and inter-governmental cooperation, researchand development and finance. A challenge will be to generate the additional green
electricity to achieve this vision. Better use of existing roads through a modal shift to public
transport or infrastructure designed for walking and cycling could decrease carbon
emissions in the short to medium term and reduce the requirement for additional
electricity generation.

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11.3 OPERATIONS ON THE ROAD NETWORK
Vehicles operated by road administrations
All road administrations have vehicle fleets ranging from cars and vans to heavy equipment
such as snow ploughs and gritters. The use cases and issues regarding fuels are as for othervehicles described above.
Road administrations may have a role in testing and demonstrating the use cases ofalternate fuel vehicles, whilst helping develop the fuelling infrastructure as a single depot
can service many vehicles.
LED lighting
Many countries are striving to move to more efficient lighting technology, forenvironmental reasons, and for economic and safety reasons.
In countries where solar gain is abundant, solar lighting solutions can provide drivers witha greater sense of security at night, and greatly improve safety for all road users.
Additional recommendations and considerations for roads authorities when planning alighting scheme are presented in Table 9.
The carbon savings from switching to LED lighting depends greatly on type of system being
replaced, the sophistication of the system being installed and the source of power tooperate the lighting (e.g., fossil fuels or renewable). Globally, the world has approximately
363 million streetlights. It is estimated that by replacing an additional 10% with LED
technology, global annual reductions of between 2.5 – 16.5 MtCO2 could be achieved.
Carbon Offsetting
Carbon offsetting is seen as a potential means of achieving carbon neutrality for difficult todecarbonise sectors or for residual emissions.
•
•
•

•

There are various technologies used to achieve this, including planting, improving soils,mangrove and sea grass restoration, production of biofuels and direct air capture.
Some approaches are associated with additional benefits, such as supporting biodiversity
or improving air quality
However, the scale of emissions associated with road transport means that carbon
offsetting is unlikely to be a successful route to achieving carbon neutrality, without alsoachieving substantial reductions in carbon emissions
There are concerns regarding offsetting in part because some schemes are not wellmanaged, so the true amount of carbon removed is not known. There is also considerable
uncertainty over the time period for which the carbon will remain locked away. For
example, whilst tree planting is seen as a positive in general, there are concerns aroundtree planting for carbon offsetting, as trees die or can get burnt down, they might competewith agricultural land and creating or protecting in one location may result in logging inanother as the demand remains the same

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There are concerns about how many, even certified schemes, result in genuinely additional
carbon removal, whilst there is an overarching concern that the potential to offset
emissions may result in a lack of action in reducing emissions
Generally, carbon offsetting should be the last resort in a strategy, with emissions
reduction, the key action

Lessons from rail sector
•
•

•

•

•

As with highways, the rail sector also has targets for decarbonisation and there is potential
good practice that can be shared.
There are good examples of measuring carbon across their network and using carbon
management systems to reduce emissions, including the use of science-based targets forcarbon reduction
There has been progress in the production of renewable energy on estates, certification ofelectricity being of green origin and power purchase agreements to fund for zero carbon
power solutions
Operations are being decarbonised, for example replacing natural gas for point heatingwith electric alternatives and diesel trains being replaced by green electric, hydrogen orbattery alternatives
Operators also often have large road fleets and are transitioning this to ultra-low emissions
alternatives

11.4 ROAD USER CHOICES
•

•
•
•
•

•

Non-Motorised Transport (NMT) not only has the impact of reducing carbon emissions, but
can also have significant economic, social and health benefits. However, it is crucial thatthe schemes are designed with NMT as a priority from inception rather than an add on to
motorised schemes.
NMT services should be provided as a network rather than as a standalone scheme.
To improve user participation, users should be involved in all aspects in the development
and implementation of NMT projects
Public bicycle sharing initiatives can be an effective means of reducing car journeys in cities.
To promote a modal shift towards public transport, a passenger centred approach is
required to provide a reliable, affordable, and efficient service that is a viable alternative to
private vehicles
Incentives such as reduced public transport cost, reimbursements, tax deductions andsubsidies can also increase public transport use. Parking fees, congestion taxes and highfuel cost can be effective to discourage private vehicle use in urban areas

Transfer to active transport
The Netherlands has a very high cycling uptake, and it is estimated that this saves 1.3 MtCO2
per year. Figures from the UK indicate that if 10% of the public moved entirely from private
car use to cycling, and annual reduction of 13.6 MtCO2 could be expected. However, thislevel of active transport is probably unlikely in many countries. In England, it is expectedthat there will be between 1 and 6 MtCO2 reduction between 2022 and 2030 due to a
reduction in car emissions by promoting public transport, cycling or walking the natural
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an estimated additional reduction between 2-13 MtCO2 could potentially be achieved
annually.

Transfer to public transport
In the USA it was estimated that in a single year, a reduction of 6.9 MtCO2 could be
attributed to the use of public transport due to the reduction in emissions from private cars
and from reduced congestion. A rough extrapolation on a global level would result in a
potential reduction of 20 MtCO2 annually, given there are 4,304,715 km of paved roads in
the US, and 12,717,850 km globally (34% in US). Figures from the UK indicate that a modal
shift from private car to bus transport for 10% of the public would result in a reduction in
the range of 5.8 MtCO2 annually. With the UK making up 3.1% of paved roads globally,
extrapolation of the figures from the UK to a global scale would lead to a reduction ofpotentially up to 190 MtCO2 annually. These figures are just indicative and the level of CO2
reduction would depend on many factors, including the availability of integrated public
transport services which are reliable and attractive to road users.
Table 18, below provides a summary of the potential carbon savings of the various
technologies described in this report in terms of low, medium, high and very high (L, M, H
and VH). These are further categorised as to whether the solution would be most applicable
to LMICs or HMICs or both, the technical ease for implementing this on a A to C scale, as
follows: A, has no significant technical obstacles; B, some technology available but requires
maturity; C, early-stage technology at least for mass adoption. Finally, the table indicateson an A to C scale the level of NRA influence as follows: NRA Scope: A, entirely within theirscope; B strong influence (e.g. requesting contractors to use warm mix); C, beyond theircontrol, but could support wider government initiatives.
.

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Table 18. Summary of solutions in achieving carbon savings

Solution

WIDESPREAD ACHIEVABILITYPOTENTIALTO TECHNICALREDUCE CARBON
EASE*

NRA
SCOPE*

M

A

A

L/H**

A/B***

A

P

M

B

A

Use of chip seal or crack seal in place of thin overlays P

P

L

A

B

Use of cement replacements in concrete roads

P

P

M

A

B

Implement circular economy

P

P

M

B

A





L

A

B

LMIC

HIC

P

P







Strategy
Purchasing of green power

Road maintenance and life extension
Maintaining roads in good condition (IRI ~ 1)
Structural health monitoring of bridges to extend
life

Low carbon materials
Use of cold mix or warm mix in place of hot mix
asphalt

P






P

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CARBON NEUTRALITY OF THE ROAD SECTOR

Solution

WIDESPREAD ACHIEVABILITYPOTENTIALTO TECHNICALREDUCE CARBON
EASE*

NRA
SCOPE*

LMIC

HIC

P

P

H

B

B

Use of additives in concrete and cement production P

P

M

B

B

Concrete recycling

P

P

H

B

B

Use of innovative high-performance concrete

P

P

M

B

B

P

L

B

A

P

M

B

B

P

M

B

C

P

L

A

B

P

L

B

C

M

A

C

Low carbon cement production

Low rolling resistance pavements
Decarbonisation of construction
construction operations

plant

Construction plant efficiency
Alternative fuels for construction plant
Alternatives to diesel powered lighting towers
Alternative fuels for diesel powered generators
Decarbonisation of road user vehicles
Alternative fuels

and



P


P




P



P

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CARBON NEUTRALITY OF THE ROAD SECTOR

Solution

WIDESPREAD ACHIEVABILITYPOTENTIALTO TECHNICALREDUCE CARBON
EASE*

NRA
SCOPE*

P

VH

B

C

P

VH

C

C

P

VH

A

C

P

VH

C

C

P

L

B

A

P

P

L

A

A





Transfer to active transport

P

P

H

A

B

Transfer to public transport

P

P

H

A

C

P

N/A

A

A

LMIC
Electrification
Hydrogen
Buses
HGVs
Operations on the road network
Vehicles operated by road administrations
LED lighting
Road user choices

Carbon Offsetting




P






HIC



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A = relatively high; C = relatively low.

**
Improvements to already good roads do not significantly improve efficiency, but emissions increase significantly where roads are in pooror very poor condition (IRI values >3). Here the potential for fuel savings is high.
***Scale of impact depends on the improvement in road roughness that is achieved.

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12 RECOMMENDATIONSMuch progress has been made, in LMICs and HICs, on establishing policies and pledges todecarbonise road transport, as seen from Part A of this report. At the time of writing, there
are large numbers of examples of NRAs across the world, demonstrating progress in
reducing carbon emissions in specific schemes and projects (with some even achieving netzero). However, it is also clear that long-term strategies for delivering the transformationneeded to become carbon-neutral or reach net-zero across all their networks are either inthe early stages of development or yet to start. Parts B and C of this report set out theapproaches available to road authorities. These examples are from many countries aroundthe world, both LMICs and HICs and the knowledge and experience are highly transferrable.
During this research the following themes have emerged as important enablers:
Strategy
For each road administration, it is necessary to develop long-term-strategy as soon as
possible, setting out a roadmap with intermediate target dates for reducing carbon
emissions. As planned and appropriately funded strategies will take time to develop andimplement, and published target dates for net-zero for most countries are within a 30-year
horizon, it is necessary to begin this process urgently. Strategies should be based on anunderstanding of where the NRA is at in terms of the carbon footprint of all its activities
and should consider all potential areas for carbon reduction: construction, maintenanceand operations as well as providing lower carbon options for road users that are practicaland affordable.
Offsetting residual emissions is viable only as a part of the solution. There are considerable
uncertainties over the quantification of carbon removal and the timescale over which it
remains locked away with existing offsetting schemes and it is becoming increasingly clearthat the role of off-setting is as an addition to carbon reduction strategies.
The appropriate solutions for individual NRAs will be driven by a combination of prevailingcircumstances, e.g., transition to EVs is developing into the stated ambition of mostcountries but the feasibility and degree of benefit may be limited by the availability not
only of the funding but also of electricity from sustainable sources.
Establishing a baseline of the sources of current emissions is an essential earlystep to identify the areas for focus and to measure progress in achieving
reductions.

Personnel
The knowledge, skills, mindsets and behaviours of the entire workforce (e.g. policy makers,
delivery teams, supply chain), all play a significant role in achieving decarbonisation as they
are collectively responsible for identifying and evaluating options, managing procurementand delivering the solutions identified. Basic carbon literacy and an awareness of theCARBON NEUTRALITY OF THE ROAD SECTOR

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carbon activities of their activities is a minimum requirement for all personnel. There is alsoa need for technical knowledge to be developed further and shared widely. This will enableroad administrations to identify optimal options and ensure that the expected benefits are
realised in practice.
Road administrations should invest in the skills and knowledge of theirpersonnel and ensure that their supply chains do likewise.

Collaboration
Some initiatives for decarbonisation will be outside the influence of individual NRAs, e.g.
incentivising uptake of EVs. In such cases NRAs can play an important enabling role, in thiscase by supporting the installation of EV charge points at accessible and convenient
locations. However, similar challenges are shared by different agencies and finding
common solutions can reduce costs and accelerate progress and there are several
examples of collaboration and knowledge sharing between NRAs. An important area thatwould benefit from increased collaboration is in the development and use of, and reporting
from, carbon measurement tools.
Road administrations should adopt a proactive role in engaging with otheragencies and leading cooperation throughout the supply chain to facilitatechange.

Procurement
The approach adopted by NRAs in procurement greatly influences the response of the
supply chain. To achieve decarbonisation, Standards (e.g. construction, maintenance,materials, safety), must actively encourage innovation and enable the development andadoption of new materials, ways of working, etc., that have lower carbon impacts. Businessmodels driving procurement must also include the evaluation of carbon and otherenvironmental impacts in addition to standard whole life cost. Consistent feedback was
obtained from the interviews carried out during this project that carbon prices, at current
levels, are not high enough to drive the procurement of lower carbon solutions.
Road administrations should review their Standards and tender evaluation
criteria so that appropriate attention and weight is given to decarbonisation.

Whole lifecycle analysis of carbon emissions
For road construction and maintenance, whole life analysis of carbon impacts is critical tounderstanding the most carbon efficient solution for specific situations. This is clear fromthe analysis of, for example, asphalt vs. concrete construction and implementation of LED

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lighting schemes. For a robust approach, it is essential for all phases of the lifecycle to be
included (many published studies omit one or more stages); a competent analysis will
declare the stages considered in relation to established standards for lifecycle analysis. The
system boundaries should also be studied carefully, in case an apparent reduction inemissions in one area results in displacing the burden to a different part of the process. The
analysis requires estimation and so sensitivity analysis is essential so that critical influences
can be identified and the uncertainties associated with them acknowledged.

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Road administrations should develop the assessment of carbon impacts withinwhole life cycle analysis and make this a routine part of options appraisal.

Data
A striking finding from the gap analysis is the limited rigour of the evidence presented on
the actual or potential reductions in carbon emissions due to adopting particular strategies
when implementing projects. As it stands, this makes it difficult for road administrations tolearn from the experience of others and assess how best to pursue their own goals ofcarbon neutrality. Furthermore, transparency over the performance of goods and services
is needed for road administrations to be able to identify genuinely low carbon approaches.
Data (as well as skills and tools) are needed to make the quantification of carbon impacts aroutine part of decision making.
Road administrations should support evidence gathering, data collection,
identification of success factors and sharing knowledge of lessons learned.

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13 GLOSSARY
Abbreviation

Full

BCR

Benefit cost ratio

CO2

Carbon Dioxide

CO2eCarbon Dioxide Equivalent

Carbon offsetting

Accounting for carbon emissions generated by one
process by reducing an equivalent amount elsewhere

Carbon sequestration

Removal of carbon from the atmosphere and ‘locking’ itaway either temporarily (e.g. in trees) or permanently(e.g. in rocks)

Decarbonisation

Reducing the carbon intensity of a technology or process(not necessarily to zero)

Embodied carbon

Carbon emissions generated from the manufacture of abuilt asset, e.g. concrete, asphalt and steel

EPD

Environmental Product Declaration

GHG

Greenhouse Gas

Gt

Giga tonne – 1 billion metric tonnes

HIC

High income countries

LCA

Life cycle analysis

LCC

Life cycle cost

LIC

Low-income countries

LMIC

Low and/or middle income countries. Also, lower middleincome countries

Mt

Mega tonne – 1 million metric tonnes

Net Zero Carbon

Reduction of the carbon emissions of a technology orprocess to zero overall

NMT

Non-motorised transport

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Tailpipe emissions

Emissions generated from exhaust from burning fuel in aninternal combustion engine

Ton

US – 2,000 lbs

Tonne

Metric - 1,000 kg

UMIC

Upper middle-income countries

UNEP

United Nations Environment Programme

WLA

Whole life analysis

Zero tailpipe emissions

Vehicle with no emissions from tailpipe (e.g. electricvehicle). Depending on the source of the electricity, there
could be emissions generated elsewhere (e.g. coal, oil orgas fired power station)

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14 ACKNOWLEDGEMENTS
In addition to the assistance and information provided from the Project Oversight Team,the project team are grateful to the following organisations who completed the survey
and/or conducted a telephone interview.
14.1 QUESTIONNAIRE
Organisation

Country

Dirección Nacional de Vialidad

Argentina

Austroads

Australia and New ZealandTransport for New South Wales (TFNSW)

Australia

Department of Infrastructure and Transport, South Australia
Australia
Federal ministry for climate action, Environment, Austria
Energy, Mobility, Innovation and Technology
Agentschap Wegen en Verkeer (Flemish gov’t – Ministry Belgium – Flandersof Public Works)Service Public de Wallonie Mobilité et Infrastructures

Belgium – Wallonia

Ministère des Transports du Québec (MTQ)

Canada-Quebec

Transport Canada

CanadaTransport Planning and Research Institute, Ministry of China
Transport
Instituto Nacional de Vías - Invias

Colombia

Ministerio de Obras Públicas y Transporte (MOPT) Costa Rica
Secretaría Planificación Sectorial
Department of Morbihan

FranceDevelopment Durable

FranceVegagerðin (Icelandic road and coastal authorities)

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Ministry of Public Works and Housing, Directorate Indonesia
General of Highways
Roads Bureau, Ministry of Land, Infrastructure, Japan
Transport and Tourism (MLIT)
Rijkswaterstaat

Netherlands

Federal Roads Maintenance Agency

Nigeria

Norwegian Public Roads Administration (NPRA)

NorwayGeneral Directorate for National Roads and Motorways

PolandInstitute for Mobility and Transport

Portugal

National
Company
Administration

for

Roads

Infrastructure Romania

Dirección General de Carreteras. Ministerio de Spain
Transportes, Movilidad y Agenda Urbana de España
Trafikverket, Swedish Transport Administration

SwedenFederal Office for Roads (FEDRO)

Switzerland

National Highways, EnglandUnited Kingdom-EnglandTransport for the North

UnitedRegionTransport for Wales

United Kingdom-Wales

Transport for the South East

UnitedRegionUK Department for Transport

United Kingdom-all. England
only for roads

Minnesota Department of Transportation

USA

Directorate for Roads of Viet Nam, Ministry of Transport Vietnam

Kingdom-England

Kingdom-EnglandCARBON NEUTRALITY OF THE ROAD SECTOR

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151

14.2 FOLLOW-ON DISCUSSIONS
Organisation

Name

Department for Infrastructure and Transport, Bruno Castellucci
South Australia
Slocombe
Department for Transport, UK

James Henry

Federal Highways Administration, USA

Gina Ahlstrom

Federal Office for Roads, Switzerland

Laure GauthiezandJennifer

Ministère des Transport de Québec, Canada-Quebec François Marchand and Luc Vescovi

Ministry of Public Works and Transportation, Alvaro Bermudez Pena
Costa Rica
National Highways, UKMark Emmett and Colin Holm

Transport for New South Wales, Australia

Chris RoyalTU Delft, Netherlands

Avishreshth Singh

Welsh Government, UK

Tim Barnes, Gareth Day and David
DennerCopyright by the World Road Association. All rights reserved.
World Road Association (PIARC)
La Grande Arche, Paroi Sud, 5e étage, F-92055 La Défense cedex