Sydney Harbour Tunnel reliability cable project

The Sydney Harbour Tunnel is supplied by 11kV cables from two substations, one in North Sydney and the other in Crows Nest. On two separate occasions, unplanned power outages have affected both substations simultaneously. This has resulted in the temporary closure of the tunnel and major traffic disruptions.

To reduce the likelihood of future outages, we are providing a backup power supply to the Sydney Harbour Tunnel.

Construction work to install the new cables is now complete. 

Final restoration of the impacted areas of the roads along the cable route will be completed in the coming months, in consultation with North Sydney Council.

Ausgrid investigated and decided on a cable route for the new cables taking into consideration:

• cost (minimising the impact on electricity bills)
• community and traffic impacts
• availability of space around existing utility services
• environmental and social impacts
• technical feasibility.

The new cables have been installed between Spruson Street in Neutral Bay and our two underground substations in Bradfield Park at Milsons Point.

The project involved installing new 11kV underground cables under local roads between Spruson Street in Neutral Bay and our two underground substations in Bradfield Park at Milsons Point.

Work to install the new cables involved:

• Digging trenches in roads to lay conduits (plastic pipes) to house the new cables.
• Backfilling trenches and temporary resurfacing of impacted areas (trenching and temporary resurfacing takes about three days outside each property depending on ground and weather conditions).
• Excavating underground joint bays at various locations along the cable route.
• Feeding in and joining sections of cable at the joint bay locations permanently restoring impacted areas, in consultation with the council once the overall project is complete.

Work was generally undertaken during standard construction hours, 7 am to 6 pm Mondays to Fridays, and 8 am to 1 pm on Saturdays. Night work was required in some locations along the cable route to avoid impacts on road traffic. Nearby properties were notified in advance for work outside normal hours.

Thank you for your patience and understanding during the construction work, which is now complete. Feedback from the community, councils and other authorities is appreciated and has helped us minimise impacts wherever possible.