22.3 Assessment of potential construction impacts
The data used to estimate the GHG emissions associated with construction of the project is provided in Appendix W (Detailed greenhouse gas calculations). Assumptions have been made based on industry default factors and experience with similar road tunnel projects, where necessary, to provide a quantitative estimate of emissions.
Twelve construction ancillary facilities are described in this EIS. To assist in informing the development of a construction methodology that would manage constructability constraints and the need for construction to occur in a safe and efficient manner, while minimising impacts on local communities, the environment, and users of the surrounding road and other transport networks, two possible combinations of construction ancillary facilities at Haberfield and Ashfield have been bassessed in this EIS. The construction ancillary facilities that comprise these options have been grouped together in this EIS and are denoted by the suffix a (for Option A) or b (for Option B).
The construction ancillary facilities required to support construction of the project include:
- Construction ancillary facilities at Haberfield (Option A), comprising:
– Wattle Street civil and tunnel site (C1a)
– Haberfield civil and tunnel site (C2a)
– Northcote Street civil site (C3a)
- Construction ancillary facilities at Ashfield and Haberfield (Option B), comprising:
– Parramatta Road West civil and tunnel site (C1b)
– Haberfield civil site (C2b)
– Parramatta Road East civil site (C3b)
- Darley Road civil and tunnel site (C4)
- Rozelle civil and tunnel site (C5)
- The Crescent civil site (C6)
- Victoria Road civil site (C7)
- Iron Cove Link civil site (C8)
- Pyrmont Bridge Road tunnel site (C9)
- Campbell Road civil and tunnel site (C10).
The following sections provide estimated GHG emissions for construction of the project for Option A and Option B, respectively. The remaining construction ancillary facilities (C4 to C10) are included in the assessment for each option.
22.3.1 Construction ancillary facilities: Option A
It is estimated that the project would generate about 528,000 t CO2-e where Option A is selected as the preferred construction option at Haberfield. The breakdown of emissions by scope is shown in Figure 22-1 and summarised (with numbers rounded to the nearest hundred tonnes) as:
- 132,500 t CO2-e of Scope 1 (direct) GHG emissions
- 86,000 t CO2-e of Scope 2 (indirect) GHG emissions
- 309,500 t CO2-e of Scope 3 (indirect upstream/downstream) GHG emissions.
Key emissions sources during project construction are shown in Table 22-2 and Figure 22-1. Detailed GHG emissions results are provided in Table 3-1 of Appendix W (Detailed greenhouse gas calculations).
Table 22-2 Construction GHG emissions results for Option A Emissions source GHG emi
22.3.2 Construction ancillary facilities: Option B
It is estimated that the project would generate about 516,400 t CO2-e where Option B is selected as the preferred construction option at Haberfield/Ashfield. The breakdown of emissions by scope is shown in Figure 22-1 and summarised (with numbers rounded to the nearest hundred tonnes) as:
- 125,100 t CO2-e of Scope 1 (direct) GHG emissions
- 82,800 t CO2-e of Scope 2 (indirect) GHG emissions
- 308,500 t CO2-e of Scope 3 (indirect upstream/downstream) GHG emissions.
Key emissions sources during project construction are shown in Table 22-3 and Figure 22-1. Detailed GHG emissions results are provided in Table 3-2 of Appendix W (Detailed greenhouse gas calculations).
Table 22-3 Construction GHG emissions results for Option B
22.3.3 Construction GHG emissions results
The results demonstrate a marginal difference in emissions between construction ancillary facilities Option A and Option B, with Option A estimated to generate around two per cent (11,673 t CO2-e) higher emissions compared with Option B. This difference is attributed to a larger fuel consumption and larger electricity consumption for Option A, associated with the two tunnelling sites at Haberfield compared to one site for Option B, and the additional requirements to support tunnelling activities at this additional site (eg vehicle movements, temporary ventilation and water treatment ancillary works).
The results demonstrate that the majority of GHG emissions associated with the construction of the project are attributed to indirect Scope 3 emissions (59 and 60 per cent for Option A and Option B respectively), followed by direct Scope 1 emissions (25 and 24 per cent for Option A and Option B respectively).
The embodied energy associated with the offsite mining, production and transport of materials that would be used for the construction of the project contributes the largest proportion of indirect Scope 3 emissions, accounting for around 89 per cent of these emissions for both Option A and Option B (see Figure 22-1). The use of concrete, cement and, to a lesser extent, steel would contribute significantly to Scope 3 emissions. The high proportions of emissions associated with these materials are attributed not only to the quantity required for the construction of the project, but also the emissionsintensive
processes involved in the extraction and production of these materials.
Figure 22-1 illustrates the breakdown of construction emissions by emission source and scope. The consumption of diesel fuel associated with heavy vehicle movements for the haulage of spoil, construction materials and waste contributes the largest proportion of Scope 1 emissions (68 and 67 per cent for Option A and Option B respectively), followed by the consumption of fuel for the operation of mobile construction plant and equipment (24 and 26 per cent for Option A and Option B respectively). Indirect Scope 2 emissions from the use of electricity are estimated to account for around 16 per cent of total emissions during construction for both Option A and Option B. Mitigation and management measures to reduce GHG emissions during construction of the project
are provided in section 22.7.
22.4 Assessment of potential operational impacts
Activities that would generate GHG emissions during operation and maintenance of the project include:
- Road infrastructure operation: the use of electricity for powering tunnel lighting and ventilation, operation of ventilation facilities, the operations and maintenance facility, water treatment, substation cooling, street lighting, electronic signage and other associated electrical systems
- Road infrastructure maintenance: diesel fuel use for the operation of maintenance equipment and the use of materials for maintaining road pavement
- Vehicles using the M4-M5 Link during operation: use of the M4-M5 Link during operation and the change in traffic volumes and traffic performance on alternative routes within the GHG assessment study area.
The GHG assessment results are presented in the following sections. The emission source data, and any assumptions used to estimate the GHG emissions associated with operation and maintenance of the project, are provided in Appendix W (Detailed greenhouse gas calculations).
22.4.1 Emissions from road infrastructure operation and maintenance
The estimated GHG emissions that would be generated by road infrastructure operation and maintenance activities are presented in Table 22-4. Annual operational emissions and emissions from major maintenance have been calculated according to the GHG assessment methodology summarised in section 22.1 and the assumptions and inputs provided in Appendix W (Detailed greenhouse gas calculations).
Table 22-4 Road infrastructure operation and maintenance GHG emissions results
Annual use of electricity for powering tunnel lighting and ventilation, building services, heating, ventilation and air conditioning (HVAC) systems, surface plants, wastewater treatment, pumps and drainage, communications systems, control systems, computer and safety systems, the emergency response system, operations and maintenance facility, electronic signage and other associated electrical systems would incur 42,621 t CO2-e indirect Scope 2 emissions and 6,088 t CO2-e indirect Scope 3 emissions per year.
Emission estimates for the use of fuel and materials for the maintenance of the road pavement are based on one major rehabilitation of asphalt pavement with the top 150 millimetres replaced and five per cent of pavement replaced for patching/repair every 50 years, and five per cent of concrete pavement replaced with only the top layer requiring replacement every 50 years (in accordance with ‘typical’ maintenance activities given in the TAGG Workbook).
The use of fuel and materials to undertake maintenance activities would result in around
3,271 t CO2-e direct Scope 1 emissions and around 3,462 t CO2-e indirect Scope 3 emissions. The total quantity of GHG emissions associated with the above road maintenance activities would be about 6,733 t CO2-e. Averaged over the 50 year period from the commencement of operation, this would generate around 135 t CO2-e of maintenance emissions per year.
22.4.2 Emissions from vehicles during operation
GHG emissions generated from the operation and maintenance of road infrastructure are relatively small in comparison with the indirect emissions associated with the fuel consumed by vehicles using the road network.
To assess the Scope 3 (indirect downstream) emissions associated with fuel consumed by vehicles using the project, and to evaluate any potential GHG emissions savings as a result of the project, the following operational scenarios, as presented in Table 22-5, were considered. Further description of these scenarios is presented in Appendix W (Detailed greenhouse gas calculations).
Traffic volumes were modelled for 2023 and 2033 in line with Appendix H (Technical working paper: Traffic and transport). These future years were chosen as they provide an indication of road network performance at project opening (2023), and 10 years after opening (2033).
The analysis is based on the vehicle kilometres travelled (VKT) and the average speed of vehicles travelling on key alternative routes within the GHG assessment study area, as generated by the WestConnex Road Traffic Model version 2.3 (WRTM v2.3) ie the strategic traffic model developed and operated by Roads and Maritime.
WRTM v2.3 provides a platform to understand changes in future weekday travel patterns under different land use, transport infrastructure and toll pricing scenarios. Further detail on WRTM v2.3 is provided in Chapter 8 (Traffic and transport).
The GHG assessment for operational road use involved calculation of the following inputs, using WRTM v2.3 model outputs, industry default factors, current vehicle statistics and fuel intensity projections as detailed in Appendix W (Detailed greenhouse gas calculations):
- Average speed for each road link
- VKT for both light and heavy vehicles
- Rate of fuel consumption
- Total fuel quantity
- Fuel quantity by fuel type (eg petrol, diesel, liquid petroleum gas (LPG)).
These inputs were then used to estimate the GHG emissions associated with a change in traffic volumes on the road network within the study area as a result of the project, under different future timeframes and project scenarios as identified in Table 22-5. Further detail regarding the calculation of fuel use and GHG emissions is presented in Appendix W (Detailed greenhouse gas calculations).
As the project does not replace a single existing route within the road network, the GHG assessment study area boundary was selected to include key routes which currently serve as alternative routes to the project as well as roads within the vicinity that were considered to be influenced by the project.
Key alternative routes within the GHG assessment study area boundary include:
- Parramatta Road between Five Dock and Broadway
- City West Link and Anzac Bridge/Western Distributor
- Victoria Road between Lyons Road and Anzac Bridge
- The Sydney Harbour Bridge and Sydney Harbour Tunnel
- Cahill Expressway and Southern Cross Drive
- The eastern extent of the M4 East Motorway, between Five Dock and the Wattle Street interchange
- The existing M5 East Motorway and New M5 Motorway, between the Princes Highway and General Holmes Drive
- Princes Highway, King Street and City Road, between Rockdale and Ultimo
- Roads surrounding the Wattle Street interchange, the Rozelle interchange, and the St Peters interchange.
Appendix W (Detailed greenhouse gas calculations) provides further detail regarding the GHG assessment study area.
Results of the operational road use assessment are provided in Table 22-6 and Appendix W (Detailed greenhouse gas calculations). Table 22-6 shows the difference between the total GHG emissions generated in the ‘do minimum’ (without project) and ‘with project’ scenarios for both 2023 and 2033. The final column in Table 22-6 shows the difference between the total GHG emissions generated in the ‘do minimum’ (without project) and the ‘cumulative’ scenarios for 2023 and 2033.
Table 22-6 Scope 3 operational road use GHG emissions results
The results demonstrate the benefits of road tunnel usage in urban areas, where travel along a more direct route at higher average speeds results in fewer GHG emissions being generated by road users, as reduced congestion and stop-start driving reduces the fuel used by vehicles. Despite increases to overall daily VKT on motorways and a reduction in performance of some non-motorway roads (as discussed in Chapter 8 (Traffic and transport)), a reduction in GHG emissions is estimated as a result of the project compared with the ‘do minimum’ scenario.
The results for 2023 indicate that the project is forecast to reduce annual GHG emissions by around 361,600 t CO2-e for the ‘with project’ scenario and around 602,500 t CO2-e for the ‘cumulative’ scenario, within the study area assessed, when compared with the ‘do minimum’ scenario for 2023. Over time, it is anticipated that the road network performance would improve, as traffic becomes accustomed to changes brought about by the project.
The assessment results indicate that the project is forecast to reduce annual GHG emissions by around 504,750 t CO2-e in 2033 for the ‘with project’ scenario and around 821,100 t CO2-e in 2033 for the ‘cumulative’ scenario, within the study area assessed, when compared with the ‘do minimum’ scenario. The predicted reduction in GHG emissions as a result of the project would be due to an improvement in vehicle fuel efficiency for some links within the study area as well as the operational efficiency of the project tunnels.
The magnitude of GHG emissions savings for the ‘cumulative’ scenario is attributed to, not only an increase in average speeds, but an increase in the number of vehicles shifting off non-motorway roads within the study area as alternative routes become available through the completion of projects such as the proposed future Sydney Gateway, Western Harbour Tunnel, Beaches Link and the F6 Extension.
Vehicle fuel efficiency is anticipated to improve as part of the project based on:
- An overall increase in daily VKT and a reduction in daily vehicle hours travelled (VHT) on the road network, with more trips able to be made on the network in a shorter time, primarily associated with traffic using the new motorway
- A decrease in VKT and VHT on key alternative routes and non-motorway roads
- Increased average speeds as a result of the operational efficiency of the M4-M5 Link, which would reduce the number of intersections and the frequency of stopping
- Increased average speeds on key alternative routes (non-motorway roads) within the study area due to reduced congestion.
Mitigation and management measures, including efficiencies incorporated into the project design to reduce energy and resource requirements, and therefore GHG emissions, are provided in section 22.7.
22.5 Combined project GHG emissions
The GHG emissions saving for the project of around 361,600 t CO2-e in 2023 would represent around 0.07 per cent of the Australian national inventory for the year March 2016 to March 2017, and 0.27 per cent of the NSW inventory for 2015, as discussed in section 22.2.3.
The GHG emissions saving for the project of around 504,750 t CO2-e in 2033 would represent around 0.09 per cent of the Australian National inventory for the year March 2016 to March 2017, and 0.38 per cent of the NSW inventory for 2015.
Figure 22-2 shows the nett emissions profile for the project for the assessment years of 2023 and 2033, comparing the emissions estimated to be generated by the project’s construction, operation and maintenance with the emissions savings for the ‘with project’ and cumulative scenarios compared with the ‘do minimum’ scenario.
Figure 22-2 demonstrates that emissions estimated to be generated during construction and the annual emissions from the operation and maintenance of road infrastructure would result in a nett increase of emissions generated for the project in 2023 for the ‘with project’ scenario. However, under the ‘cumulative’ scenario for 2023, emissions generated in construction and annual operation and maintenance would be offset against emissions savings as a result of improved road performance within the study area boundary. Similarly, annual operation and maintenance emissions estimated to
be generated in 2033 would be offset against emissions savings for the ‘with project’ and ‘cumulative’ scenarios.
Emissions were not able to be extrapolated beyond the operational traffic impact footprint for the project, which was assessed up to 2033. However, it is expected that the savings in emissions from improved road performance would reduce over time as traffic volumes increase.
Figure 22-2 Combined GHG emissions profile: construction, operation and maintenance emissions offset against emissions savings
As discussed, the magnitude of GHG emissions savings for the ‘cumulative’ scenario is likely to be attributed to the reduction of traffic using the existing road network within the study area as alternative routes become available through the completion of projects such as the proposed future Sydney Gateway, Western Harbour Tunnel, Beaches Link and the F6 Extension.
22.6 Assessment of cumulative impacts
22.6.1 Cumulative construction emissions
Estimated construction emissions for each WestConnex component project are presented in Table 22-7, with a summary of the cumulative emissions for each scope.
Table 22-7 Estimated construction emissions for each WestConnex component project
Mitigation and management measures would be implemented during each project to reduce GHG emissions during construction. Ongoing monitoring and reporting of project emissions would also be undertaken in accordance with the WestConnex Sustainability Strategy (Sydney Motorway Corporation 2015), as discussed in Chapter 27 (Sustainability).
22.6.2 Cumulative operational emissions
The assessment of operational road use emissions for each component of the WestConnex program of works was undertaken for a discreet study area as relevant to each project component. The individual study areas were assessed for differing operational timeframes and assesses the changes in traffic performance brought about by each project component within their respective GHG study area boundaries. As a result, it was not appropriate to add these together to quantitatively assess the
cumulative emissions of the WestConnex program of works as a whole.
However, results for each of the GHG assessments undertaken for EISs of the individual
WestConnex component projects show greater emissions savings in the ‘cumulative’ scenario compared with the ‘project only’ scenario within their respective study area boundaries. This is associated with WestConnex’s contribution to improved traffic flow on the motorway network and additional network capacity and improvements proposed as part of future projects such as Sydney Gateway, Western Harbour Tunnel, Beaches Link and the F6 Extension.
These results align with the cumulative assessment presented in Appendix H (Technical working paper: Traffic and transport), which shows greater reductions in daily VKT and VHT for the ‘cumulative’ scenario compared with the ‘with project’ and ‘do minimum’ scenarios for key alternative routes and non-motorway roads, and a reduced daily VHT for the ‘cumulative’ scenario for motorways.
Despite increases to overall daily VKT on motorways, improvements to traffic flow and congestion are achieved through increased speeds and reduced frequency of stopping, as well as reduced daily VKT and VHT on alternative routes and non-motorway roads, which results in improved fuel efficiency and subsequently reduced GHG emissions associated with road use. Future improvements in vehicle fuel efficiency are also taken into account, as described in Appendix W (Detailed greenhouse gas calculations). It is expected that savings in emissions from improved road performance would reduce over time as traffic volumes increase.
22.7 Management of impacts
22.7.1 Management of emissions through design
The design of the project has been optimised such that measures to reduce energy and resource requirements, and therefore GHG emissions, are inherent in the design. Design development from the M4-M5 Link preliminary design, as discussed in Chapter 4 (Project development and alternatives), has been optimised to include:
- Refinement and revision of the alignment of the mainline tunnels, reducing the length of the mainline tunnels between the Wattle Street interchange and the St Peters interchange, thereby reducing the volume of spoil generated, materials used, lighting and ventilation required, and emissions generated from operational road use by vehicles
- Reduced energy and resource consumption, and spoil generation, during tunnel excavation, through selection of roadheaders and drill and blast for excavation, as opposed to the use of a tunnel boring machine. The latter option consumes more electricity, potable water and concrete, and generates more spoil
- Reduced energy and resource consumption through an LED lighting design. The design significantly reduces the number of fittings required in comparison to similar existing NSW tunnels which use end-to-end fluorescent fittings or high-pressure sodium lights. When compared to interior zone tunnel high-pressure sodium lights, as used on the East Link and Airport Link, the number of fittings can be reduced with LED lights as they can be oriented to spread the light evenly whilst meeting lighting standards. LED light banks also have a longer operational life and
lower operational power demand
- Reduced power consumption through the design of the ventilation system, which incorporates low pressure fans that consume about 50 per cent less energy compared with a high pressure fan solution. These low pressure fans are oriented vertically which also reduces the total ventilation structural footprint by 20 to 30 per cent, reducing the amount of embodied energy associated with construction materials used
- Optimal tunnel ventilation power consumption by locating the ventilation facilities close to the main alignment tunnel portals, thereby optimising the piston generated vehicle effect
- Mainline tunnels and the associated surface road network designed for long term performance and durability of materials, increasing asset design lives and reducing the frequency of maintenance activities
- The project would facilitate improvements to pedestrian and cyclist paths, linking existing active transport networks with new connections at Rozelle and St Peters, and reducing the need for reliance on road transport between these communities.
22.7.2 Next steps for emissions reduction
Table 22-8 provides a list of mitigation measures to be incorporated during the construction and operation of the project, in accordance with the WestConnex Sustainability Strategy, to further reduce the GHG emissions generated by the project.
Table 22-8 Environmental management measures – GHG
Emission of greenhouse gases during construction
GHG1 An Energy Efficiency and Greenhouse Gas Emissions Strategy and Management Plan will be prepared for the project as part of the project’s Sustainability Management
Plan and will be implemented to assist in achieving ‘Design’ and ‘As Built’ ratings of Excellent under the Infrastructure Sustainability Council of Australia infrastructure rating tool.
GHG2 Undertake an updated GHG assessment based on detailed design for ongoing monitoring and review of emissions during construction.
GHG3 Opportunities to use low emission construction materials, such as recycled aggregates in road pavement and surfacing, and cement replacement materials will be
investigated and incorporated where feasible and costeffective.
GHG4 Construction plant and equipment will be operated and maintained to maximise efficiency and reduce emissions, with construction planning used to minimise vehicle wait times and idling onsite and machinery turned off when
not in use.
GHG5 Locally produced goods and services will be procured where feasible and cost effective to reduce transport fuel emissions.
GHG6 At least 20 per cent of construction energy required for the project will be sourced from an accredited GreenPower energy supplier, where possible. Six per
cent of construction electricity requirements will be offset, with any offset undertaken in accordance with the Australian Government National Carbon Offset Standard
Emission of greenhouse gases during operation
OGHG7 The tunnel will be designed with appropriate vertical alignments and grades to allow vehicles to maintain constant speeds and minimise fuel use to reduce potential greenhouse gas emissions. Construction and operation
OGHG8 Energy efficiency will be considered during the design of mechanical and electrical systems such as the tunnel ventilation system, tunnel lighting, water treatment
systems and electronic toll and surveillance systems. Energy efficient systems will be installed where reasonable and practicable.
OGHG9 At least six per cent of operational energy required for the project will be sourced from an accredited GreenPower energy supplier and/or through renewable energy generated onsite. Opportunities for operational energy offset, in accordance with the Australian Government National Carbon Offset Standard, will be considered
during detailed design. Operation