Transgrid has published the Project Assessment Conclusion Report (PSCR) for managing risk on Line 11 (Dapto-Sydney South). Publication of this PACR represents the last step in the Regulatory Test for Transmission (RIT-T) process.
Line 11 is a single circuit steel tower 330 kV transmission line between Dapto and Sydney South substations, with a route length of 68km. There are 154 structures on this single circuit line including 129 suspension towers and 25 tension towers. The line is a key link in the Sydney South coastal region, and its route traverses urban areas near the substations, bushland in the Illawarra Escarpment, Sydney Water Catchment and National Park areas and crosses the Princes Motorway (M1) at several locations.
Detailed analysis of asset condition information indicates that almost all suspension structures and/or other components on Line 11 have condition issues of some form (structure and conductor) including grillage deterioration which increase the probability of asset failure. This presents a bushfire and safety risk which Transgrid is obligated to manage. The proposed investment will enable us to continue to manage and operate this part of the network to a safety and risk mitigation level of ‘As Low As Reasonably Practicable’. Consequently, it is considered a reliability corrective action under the RIT-T.
Two credible network options have been identified that meet the underlying need from a technical, commercial, and project delivery perspective. Option 1 involves the replacement of 43 suspension structures, replacement of insulators, and refurbishment of assets, and has a capital cost of $41.15 million ($2025/26). Option 2 involves the replacement of 98 suspension structures, replacement of insulators, and refurbishment of assets, and has a capital cost of $74.47 million ($2025/26).
No submissions were received in response to the PSCR during the consultation period which closed in July 2025, and no additional credible options have been identified.
We consider both Option 1 and Option 2 to be the preferred options in accordance with NER clause 5.15A.2(b)(12). As the net benefit for Option 2 is less than 1% higher than Option 1, we consider both options to equally maximise the net present value of the net economic benefit to all those who produce, consume and transport electricity in the market.
However, due to the significant difference in capital expenditure, specifically Option 2 being 81% more expensive than Option 1 and only delivering less than 1% more benefit, we have decided to progress with Option 1. The additional access requirements (for larger vehicles to access a greater number of locations in Option 2) and uncertainty associated with boring in areas where rock is present, means that Option 1 provides greater certainty regarding site work. A reduced number of structure replacements has reduced potential for weather related, other delays and additional expenditure due to encountering rock and reduced environmental impact.
Option 1 is the most prudent and economically efficient solution to manage and mitigate safety and environmental risk to ALARP.
In accordance with the requirements of the Rules, a summary of the Project Assessment Conclusion Report is made available on the AEMO website. A copy of the PACR can be obtained from Transgrid’s website or by emailing [email protected].