New substation jump starts construction of Torrens to Darlington Project

Works have commenced on a dedicated electricity substation at Tonsley, which will be used to power the tunnel boring machines (TBMs) that will dig the first two tunnels for the Torrens to Darlington (T2D) Project. 

Tonsley East Substation is going to be built, owned and operated by SA Power Networks. The new facility will stand on the site of the recently demolished former Mitsubishi building adjacent South Road and it will be part of T2D’s Southern Laydown Area. 

“It is always exciting to partner with State and Federal Governments to deliver a significant new electricity supply for a major project of great benefit to the community. This is a game-changing infrastructure project for South Australia and it is exciting to be involved. 

“Whether it is this important transport project, development of major defence industry at Osborne, or projects such as the new Women’s and Children’s Hospital, reliable and dedicated electricity supply is absolutely crucial. This new substation will meet the significant demand and specific voltage requirements to power the tunnel boring machines as well as long-term power needs for the North-South Corridor,” SA Power Networks CEO Andrew Bills said. 

Construction on the substation started in March of this year following clearance of the site as well as completion of ground investigations and detailed design of the facility. Works are estimated to take about a year to complete. 

In early August, two 66,000-volt transformers were installed at the substation as part of its construction. 

“The Tonsley East Substation will play an instrumental role in building the River Torrens to Darlington Project, and the ramping up of work on the plant represents a real milestone. 

“Following on from extensive preparatory works – such as ground investigations, the relocation of utilities and demolitions – the building of the substation is the first example of genuine construction on the motorway. 

“It will occupy the site of the large former Mitsubishi building that used to front South Road, and it will help provide a dedicated and reliable source of energy for the crucial initial stage of the Project,” Minister for Infrastructure and Transport Tom Koutsantonis said. 

The substation will supply electricity to the TBMs and to the two parallel 4-kilometre Southern Tunnels once they are completed in 2030. The delivery of the Tonsley East Substation – undertaken by SA Power Networks and its subsidiary Enerven – is the first construction to commence in direct relation to the T2D Project. 

Tonsley East Substation is due to be fully operational well ahead of the expected start of TBM activities on the Southern Tunnels. In addition, a smaller substation is going to be established in the Richmond area to power the TBMs that will excavate the 2-kilometre Northern Tunnels. 

These substations will ensure the operation of the TBMs will have a reliable and dedicated source of electricity. 

“Construction of the substation over the coming year means that it will be well and truly established before the scheduled start of TBM activity in 2026. 

“It will also serve as a precedent for a second substation to power the TBMs that will excavate the parallel Northern Tunnels from 2029. 

“The decision to build the two facilities allows the T2D Project to draw on a dedicated energy source without needing to tap into Adelaide’s wider power distribution network,” Mr Koutsantonis said. 

The Torrens to Darlington Project is the final and most complex section of the North-South Corridor, completing the 78-kilometre non-stop motorway between Gawler and Old Noarlunga. This 10.5-kilometre corridor is the most significant infrastructure project to be undertaken in South Australia. 

The T2D Project is comprised of two sets of twin tunnels – Northern and Southern Tunnels – as well as lowered and ground-level motorways, overpasses and underpasses, and upgraded at key intersections. 

Once completed, about 50 per cent of T2D will be tunnels. The Southern Tunnels will run from Clovelly Park to Glandore while the Northern Tunnels will run from Richmond to West Hindmarsh. 

Main construction on the T2D Project is expected to commence in 2025, with project completion expected in 2031. Once up and running, T2D will enable motorists to have a travel time of about nine minutes from West Hindmarsh to Darlington. 

The overall T2D Project is anticipated to support an average of 5,500 jobs annually during main construction. 

Source: Government of South Australia – Media Releases; T2D Torrens to Darlington (1, 2)