The Tonsley East Substation – to be built, owned and run by SA Power Networks – is being established on the site of a recently demolished former Mitsubishi building in Adelaide and will constitute part of the project’s Southern Laydown Area.

Work on the new facility – which will supply electricity to the TBMs and then to the two parallel 4km Southern Tunnels once they are completed in 2030 – is the first construction in direct relation to the T2D project. The work will be undertaken by SAPN and its subsidiary Enerven.

Following site clearance, and completion of ground investigations and detailed design of the substation, construction began in March and is expected to take about one year to complete.

As part of the construction, two 66,000-volt transformers were installed at the Tonsley East Substation in early August.

The substation will be fully operational well ahead of the expected start of TBM works on the Southern Tunnels. A similar one will be established in the Richmond area to power the TBMs that will build the 2km Northern Tunnels.

The substations are being set up to ensure TBM operations have a reliable and dedicated source of electricity.

The 10.5km T2D Project is the final and most complex section of Adelaide’s 78km North-South Corridor and the most significant infrastructure project ever undertaken in South Australia.

It comprises two sets of twin three-lane tunnels, lowered and ground-level motorways, as well as overpasses and underpasses and upgrades at key intersections. More than half of the project will be tunnels.

In April, potential bidders for the main construction contract were invited to lodge a formal Expression of Interest.

In July, the South Australian government released a market call for land for the project’s tunnel segment precast facility. The site will be ready for use by mid-2024, allowing works on the precast manufacturing facility to start after the main contract has been awarded, which is also expected in mid-2024.

Main construction works are planned to commence in 2025, with tunnelling works for the Southern Tunnel planned to start in 2026. The entire T2D Project will be open to traffic in 2031.