Reducing Greenhouse Gas Emissions in Road Construction – Preliminary Analysis

Road Construction GHG Emissions – Preliminary Analysis Page 2 of 8

Prepared for

Local Government Audience

Version Author Date Description of changes

V1a Paul Brown 20/8/2019 Generic document for release

V1b Paul Brown 22/10/2019 Revision of next steps

V1c Matt Sullivan-Kilgour 23/10/2019 Review

V1d Paul Brown 13/11/2019 Greater Sydney Update

Prepared by

Ironbark Sustainability

Suite 8, 70-80 Wellington St, Collingwood 3066

ABN: 51 127 566 090

Ph: 1300 288 262 | info@realaction.com.au | www.realaction.com.au

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About Ironbark Sustainability

Ironbark Sustainability is a specialist consultancy that works with government and business around

Australia by assisting them to reduce energy and water usage through sustainable asset and data

management and on-the-ground implementation.

Ironbark has been operating since 2005 and brings together a wealth of technical and financial analysis,

maintenance and implementation experience in the areas of building energy and water efficiency, public

lighting and data management. We pride ourselves on supporting our clients to achieve real action

regarding the sustainable management of their operations.

Ironbark are a certified B Corporation. We have been independently assessed as meeting the

highest standards of verified social and environmental performance, public transparency, and

legal accountability to balance profit and purpose.

Our Mission

The Ironbark mission is to achieve real action on sustainability for councils and their communities.

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Please note this is a fast-moving area and recommendations and approaches are expected to change

over time. Ironbark are happy to discuss the current state of play or provide other relevant contacts for

organisations seeking to progress this opportunity further.

1. Sustainable Infrastructure - Road Construction Councils construct, specify and fix many kilometres of

road each year. This construction and maintenance

work produces large amounts of greenhouse gas

emissions and has substantial potential for utilising

recycled or lower footprint materials to reduce these

emissions.

Typically, the emissions from this source are

considered “industrial processes” and not presently

included within most councils greenhouse gas

inventories. As we progress on climate change action, however, these emission sources will

likely begin to be included. This document provides a summary of the high-level analysis of the

road construction program within a Victorian growth area council and the opportunities for

improving sustainability outcomes.

Update: Since completing the analysis for a Victorian Growth Area Council we have completed

the same for one of the fastest growing councils in Greater Sydney. The results? Very, very

similar savings in both materials and greenhouse emissions from some minor tweaks to their

infrastructure guidelines. Total annual savings were between 3,000 and 5,000 tonnes of CO2/yr

and the utilisation of between 8,000 and 20,000 tonnes of recycled material.

1.1 Background to current road construction Councils are responsible for a wide range of hard surface infrastructure construction repair and

specification, that includes for the following:

Roads

Footpaths and driveway cross overs

Shared paths

Car parks

Drainage and water infrastructure

Outdoor sporting courts such as tennis, netball, basketball and skating

For this study the Council selected currently inherits approximately 41km of roads and drainage

every year from developers constructing to Council and VicRoads specifications. This section

analyses the options for improving the sustainability of this construction work.

1.2 Opportunities for improving sustainability outcomes

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For the purpose of this work an analysis of the sustainability impact of elements of road

construction were quantified using the Infrastructure Sustainability Council of Australia (ISCA)

materials calculator.

The specific elements that were included in the analysis included:

Road construction - asphalt course

Road construction – kerb and channel

Footpath and cross over construction – concrete

As such this work should be considered for what it is:

A simple review of the potential impacts and opportunities from improved sustainability in

infrastructure.

It is not designed to be exhaustive or all inclusive but should target the primary opportunities

available for this emissions source. Importantly the comparison of the different ways of

constructing the various infrastructure elements are all approved by VicRoads.

Table 1 outlines the three scenarios used to estimate the impact of different specifications on

the sustainability of the 41 km of road construction. This includes a simple increase in the

amount of recycled or reused materials as well as replacing hot mix with warm mix asphalt. All

options are approved for use by VicRoads.

Table 1: Infrastructure construction options considered in this analysis

Scenario Infrastructure

type Description

Current Specification

Asphalt Asphalt, standard hot mix, 5.5% virgin bitumen (0% RAP). Calculation based on Vicroads spec 407 and 41km x 6m width x 80mm depth

Footpath Combined Footpath and Footpath cross overs, assuming one footpath length throughout the road network.

Footpath. Assume 80mm depth x 1.4m x 41km footpath. Assume 90% of path length.

Footpath cross over (path only). Assume 150mm depth x 1.4m footpath. Assume 10% of path length.

Kerb & Channel As per VicRoads spec 703. Local Streets – N25 portland cement–based concrete. Analysis excludes impact of steel reinforcement. Assumes kerb and channel 41km x2.

Partial Sustainable Specification

Asphalt As per current specification and warm mix.

Footpath As per current specification and assume 50% geopolymer instead of portland cement (25% slag, 25% flyash).

Kerb & Channel

Leading Sustainable Specification

Asphalt Asphalt, warm mix, 3.5-4.4% virgin bitumen (20-40% RAP). Asphalt is to include maximum amount of recycled material as per VicRoads standards.

Footpath As per current specification and assume 100% geopolymer instead of portland cement (50% slag, 50% flyash).

Kerb & Channel

It needs to be noted that further sustainability improvements can be made when considering all

aspects of road and path making including the types of base and the use of additional recycled

Road Construction GHG Emissions – Preliminary Analysis Page 5 of 8

materials. As Council develops experience with the strategies outlined above, these additional

improvements can be considered for future implementation.

Table 2 provides a summary of the sustainability benefits

of changing road construction specifications. The

calculations show that compared to the current Council

specification the amount of recycled material could

increase by as much as 10,000 tonnes of material per

year, which is 30% of total materials used. In addition,

the overall greenhouse gas emissions can be reduced by

around 4,800 tonnes per year which is 60% of emissions.

Table 2: Results of sustainability options analysis - 41km of annual road construction

Scenario Infrastructure type

Total recycled content (m3)

Percentage of recycled material

Greenhouse emissions (tCO2-e)

Greenhouse emissions (tCO2-e/km)

Current Specification

Asphalt 0 0% 2,794 68

Footpath 0 0% 1,776 43

Kerb & Channel 0 0% 3,492 85

Totals 0 0% 8,062 197

Simple Sustainable Specification

Asphalt 0 0% 2,532 62

Footpath 774 16% 1,084 26

Kerb & Channel 1,522 16% 2,131 52

Totals 2,296 7% 5,747 140

Leading Sustainable Specification

Asphalt 5,904 30% 2,100 51

Footpath 1,548 31% 391 10

Kerb & Channel 3,044 31% 770 19

Totals 10,496 30% 3,262 80

The majority of the greenhouse gas emissions savings

from the improved specifications is through the use of

high recycled content within the concrete (see

Figure 1).

From a materials perspective the asphalt has the greatest

opportunity for increasing the volumes of recycled

material use (see Figure 2).

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Figure 1: Road Construction by Emission Source (tCO2-e)

Figure 2: Road Construction by Recycled Content (m3)

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000

Current

Simple Improvements

Leading

Asphalt Footpath Kerb & Channel

0 10,000 20,000 30,000 40,000

Current

Simple Improvements

Leading

Asphalt Footpath Kerb & Channel Non recycled materials

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1.3 Evidence-based Climate Change Mitigation Programs So, what comes next?

Ironbark work with a wide range of councils who take different approaches to dealing with an

issue like emissions from road construction. In order to frame these options, we use a typical

project cycle to describe the different options for a given Council (see Figure 1).

Figure 3: Corporate or community evidence-based climate change mitigation program cycle

Within this cycle there are a range of activities that should be embedded by councils into

standard practice. These are discussed below.

1.3.1 Insight

During the Insight stage councils collect information on both their corporate and community

greenhouse gas emissions. For the purpose of road building it is recommended to:

Include the emissions from councils’ road construction and repair program within

Council’s corporate greenhouse gas inventory1

Include the emissions from road construction by other organisations (e.g. developers)

within the municipal greenhouse gas profile1

1.3.2 Target

During the Target stage we are not envisaging that this issue will significantly affect the targets

Council determines. However, where targets are based on what emission reduction project s

can be delivered then including relevant actions within road construction and repair is highly

recommended.

1.3.3 Strategy

During the Strategy stage we recommend a review of the opportunities identified within this

document be undertaken and specifically:

Discuss with state government including Sustainability Victoria and representatives of

the Victorian Chief Engineer to assess appropriate scope and recommendations

1 This is included as standard within Ironbark’s’ emissions inventory and profile work for councils

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Council infrastructure and environment teams be consulted to discuss opportunities to

expand the scope of specification changes and to confirm assumptions, preferred

approaches and underlying outcomes

1.3.4 Action

During the Action stage the following activities should be undertaken

Redraft Council specifications

Consult on revised specifications with contractors

Finalise specifications

Communicate what has occurred to the sector and encourage expansion beyond your

Council are to the region or state

1.3.5 Evaluate

The process outlined above is a process, not a singular outcome. In order to introduce a

systematic approach to improving the sustainability of road and path construction an annual

approach to measurement evaluation, reporting and learning/improvement is required. In order

to deliver this the following is recommended to be included within Council’s infrastructure and

sustainability reporting framework:

Audit and calculate the cost and greenhouse implications from changes to Councils and

other organisations infrastructure specifications compared to the current approach

Analyse additional areas for improvement considering infrastructure type (e.g. can

expand the coverage to include new areas of focus such as specifications for car parks,

outdoor sporting courts etc.) or increase the depth of analysis to include further items

such as road base, land clearing and street tree plantings