What we’re building for the Hunter Transmission Project

We’ll build 2 new switching stations – 1 near the existing Bayswater substation and another at a former timber plantation site in Olney State Forest. 

Switching stations are facilities that contain high-voltage equipment used to connect different parts of the electricity network and help manage how power flows. We need the 2 new switching stations to connect the new transmission line to the existing 500 kV network. 

Each site will include high-voltage switchgear, control buildings and associated infrastructure, with a short overhead line connecting the switching stations to the main transmission line. 

We considered a range of factors when selecting the location for the new switching stations, including proximity to the existing network, access, network performance, and minimisation of environmental and land use impacts.

Upgrades at the existing substations at the Bayswater and Eraring power stations will be needed to connect the HTP to the electricity network. 

All upgrades will take place within the existing substation sites, so no extra land or vegetation clearing will be needed. 

At Bayswater, we’ll connect the new Bayswater South switching station with a short one-kilometre double circuit line, install two new switchbays (which help control how power flows through the substation), and expand the substation footprint to fit new equipment. 

At Eraring, we’ll install new landing spans (short overhead lines connecting the transmission line into the substation), upgrade some existing equipment so it can handle more load, relocate or upgrade switchgear, and add new transformer units and associated equipment. 

These upgrades won’t change how the substations operate and there will be no increase in operational noise or electromagnetic fields (EMF).

If the Hunter Transmission Project is approved, some public roads, intersections and access tracks will need to be upgraded, and in some cases new access tracks will need to be built. 

This will occur in places where they simply aren’t wide enough or suitable for large trucks carrying oversize loads of construction equipment, plant machinery and the transmission towers. 

Access roads and tracks will also be needed for maintenance when the new transmission infrastructure is operational. 

We’ll consult with Transport for NSW and local councils through detailed design and construction to ensure safety and minimise disruptions. 

Read more in our traffic and transport impact assessment fact sheet (September 2025).

We’ll build temporary construction support sites to house workers, store materials and stage the transport of equipment for the HTP. 

Five temporary support sites are proposed at Muswellbrook, Millfield, Howick, Gouldsville and Cooranbong. Three of these sites would include temporary workforce accommodation, with space for around 780 workers. 

The sites will serve as bases for construction activities and could include facilities and amenities such as kitchens and recreation areas, demountable offices, and areas for storing equipment, materials, chemicals and gas. 

We’ll also set up temporary laydown areas along the transmission line route to support flexible construction staging. These areas will be used for stockpiling materials, setting up equipment, managing traffic, and helping to reduce vehicle movements to and from the main compounds. Laydown areas are generally located where more accessible and less accessible construction zones meet. 

Read more in our temporary construction support sites fact sheet (September 2025).

To support the construction of the Hunter Transmission Project we’ll need to make adjustments to some existing 330 kV and 500 kV transmission lines operated by Transgrid, along with some lower voltage lines operated by Ausgrid and mining infrastructure owners. 

We’ll also upgrade overhead earth wires and install new communications systems on a number of existing 500 kV transmission lines operated by Transgrid. These upgrades help protect the network from lightning strikes and improve monitoring to quickly detect faults. 

Where possible this work will occur within existing easements to minimise impacts.