Construction along the alignment
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There are two work sites along the project alignment at Wilson Road, Pennant Hills and Trelawney Street, Thornleigh.


Construction is underway to turn these tunnel shafts into permanent facilities that will be used when the tunnel is operational.

A fact sheet is available.

Current work


We are building the pavement in three main layers; a layer of no fines concrete as the base of the pavement, a sealing layer of asphalt and a final layer of continuously reinforced concrete pavement. Concrete roads are highly durable. 

Most paving is completed at night to avoid concrete trucks causing congestion on Pennant Hills Road. About 12,000 cubic metres of concrete is being used across the project each week, supplied by NorthConnex’s dedicated batching plant.

Concrete paver


The southbound and northbound tunnels are joined by cross passages, which are spaced about every 120 metres. The cross passages house tunnel operations equipment. Work is continuing to build walls, floors and roofing in the cross passages known as blockwork.


The tunnel roof is being painted matte black to minimise distractions for motorists. The painters hand-spray the paint onto the tunnel roof in sections, using elevated work platforms.

The roof is painted black

Permanent Above Ground Facilities

Building the Trelawney Street and Wilson Road tunnel support facilities involves fitting axial fans in the tunnel shafts, removing the acoustic sheds and building permanent surface buildings and landscaping.

Coral Tree Drive Substation

Completed work

We have already finished a lot of work in this section including:

  • In early 2016 shaft excavation was carried out to reach the required tunnel depth
  • During tunnelling 20 roadheaders were used. Roadheaders have a rotating, rock-cutting head on the front, mounted to a boom. When the underground rock is cut, a loading device transfers the rock onto a conveyor belt which moves the spoil onto haulage trucks. Roadheaders travel on bulldozer style tracks and weigh around 100 tonnes
  • Benching involves removing the lower part of the tunnel to achieve the desired final height. Two surface miners were used to complete this work. Surface miners have large cutting drums and can cut about 50 centimetres deep as they travel along the tunnel floor. Roadheaders are also used to carry out benching using a large cutting boom on the front of the machine
  • Trenching has been carried out to create space for drainage and electrical infrastructure
  • Waterproofing has been installed as a plastic or spray lining
  • A final layer of concrete has been installed and smoothed to form the tunnel shell, ready for fit out with road pavement, panelling and electrical and mechanical equipment.

Upcoming work

Reflective panelling

Reflective panelling is being installed along the tunnel alignment. The panels maximise light reflection and generate a feeling of spaciousness for the driver. To install them we build a frame on the tunnel wall and then attach the panels.

Framing for reflective panels

Mechanical and electrical fit out

The Mechanical and Electrical Team is installing lighting, fire deluge systems (high flow fire sprinklers), CCTV cameras, cable trays, jet fans and other tunnel systems. Most equipment is placed in the cross passages and in the tunnel roof.

Lighting – we are installing LED lights every 12 meters inside the tunnel. They are mounted on cable trays, which are installed in the tunnel roof.

Fire deluge systems – about 120 metres of fire deluge system is installed every week. This involves the team installing high flow fire sprinklers into the tunnel.

CCTV Camera installation – we are installing more than 700 CCTV cameras in the tunnel which will be used to monitor conditions inside the tunnel once it opens to traffic. Footage will be viewed from the Motorway Control Centre.

Cable tray installation we are installing more than 30 kilometres of cable trays inside the tunnel. To do this, we fix prefabricated brackets into their final position and lock them into place in the tunnel roof.

Jet fans – 140 jet fans are being installed in the tunnel. We do this by mounting jet fans to a cradle in the tunnel roof and bolting the fans into place. A safety chain is then fitted on the fan for additional security.

Once equipment is installed, commissioning works must be completed. You can read more about the commissioning process here

Lighting installation
Fit out of jet fans

Project timeline

Construction updates

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