Frequently asked questions

Generally, we’ll follow the same construction method to build the Rozelle Interchange tunnels:

1. Firstly, using a roadheader we excavate the top section of the tunnel commonly known as heading excavation. We excavate between 1 metre and 5 metres at a time before installing ground support

2. A geotechnical engineer then checks the tunnel face to make sure the ground conditions are consistent with the geotechnical model, and that the proposed ground

support is appropriate

3. We then install rockbolts into the roof of the tunnel. These bolts are tensioned and injected with grout to provide a durable and long-lasting ground support

4. The tunnel roof (crown) and sides are then sprayed with concrete lining (shotcrete) for additional support

• We later return to excavate the floor of the tunnel which is known as benching. We may use a roadheader, a smaller machine called a surface miner or a rockhammer attachment on an excavator

• The construction method can be adapted to suit various ground conditions by using a range of ground support options. This may include excavating in shorter distances, inserting a higher density of rockbolts or spraying a thicker layer of shotcrete

• The tunnels will be dug by a machine called a roadheader that uses a rotating head on a moving boom, to excavate the rock. Roadheaders have been chosen because they are best suited to digging road tunnels as their arm can provide the arched roof shape and a flat base, suitable for road construction

• There will be 22 roadheaders working on the Rozelle Interchange during peak construction. Each roadheader weighs about 135 tonnes and is capable of removing close to 7.5 million tonnes of spoil

• To support the completed excavation, a rockbolting machine is used to install rockbolts into the tunnel roof. Rockbolts range in length depending on the ground conditions and excavation size. The longest rockbolt on the Rozelle Interchange project is 9 metres. The rockbolts are drilled, tensioned and injected with grout to increase the strength of the tunnel roof

• Shotcrete is then applied to keep the tunnel roof and sides in place. The amount of shotcrete applied depends on the ground conditions and the excavation size

• Moxie’s are specialized dump trucks used to transport spoil inside the tunnels to the acoustic shed. The spoil is then loaded onto large trucks with trailers and taken off site to approved spoil tip sites. Receiver sites for spoil from the Rozelle Interchange are located mainly out west and include future developments

• The Rozelle Interchange is delivering the largest road tunnel network in Australia

• Whilst the Rozelle Interchange is a complex tunnelling project, construction of multiple tunnels has been done before. A highly complex tunnel network exists under the Sydney CBD where rail tunnels intersect with road tunnels, pedestrian tunnels and utility tunnels. These have also been constructed within proximity to heritage structures and multi storey buildings with deep basements

• There are many other examples of multiple tunnels located underneath properties in Sydney and around the world. Sections of WestConnex M4 East & M4-M8 Link Tunnels, Airport Link (Brisbane) and the Crossrail project in London to name a few. Most underground rail networks in major cities overlap each other underneath properties

• The same limits for settlement apply to the whole tunnel alignment regardless of the number of tunnels, the size of the excavation or the depth of the tunnels

• The same well-established construction techniques used for the Sydney region will be followed to build the Rozelle Interchange tunnels

• During the design development phase, a detailed geotechnical model is created to understand the ground and hydrogeological conditions along the tunnel alignment. The hydrogeological model is developed in consultation with Department of Primary Industries (Water) and provided to the Department of Planning, Industry and Environment (DPIE), and the geotechnical model is reviewed by the Independent Certifier and roads and Maritime experts to ensure it is suitable

• To gather geotechnical information the project undertakes borehole samples of the ground close to, and at a distance from the tunnel alignment. 962 borehole samples will be taken along the Rozelle Interchange tunnel alignment. This information is used to develop the Geotechnical and Hydrogeological models

• The geotechnical and hydrogeological models take into account the total number of tunnels to assess any potential cumulative impact

• Four rounds of design development occur from Concept Design to Final Design. Each round is produced by a specialist design consultancy and needs to be reviewed by three parties (JHCPB, TfNSW and the Independent Certifier) before it can be issued for construction

• This thorough review process is intended to ensure technical requirements are met and that the methodology is appropriate for the ground conditions

• Removal of ground mass does not necessarily mean movement on the surface, particularly when excavating in good ground conditions. The Rozelle Interchange is located almost entirely in Hawkesbury Sandstone. This is a strong and consistent rock making it ideal for tunnelling

• Where possible, the tunnel design has been developed to limit any cumulative impacts including placing wider excavations deeper underground where possible and optimising the distance between the tunnels.

• No. Water retention of the topsoil’s will be regenerated by rain as usual. With water only able to travel through joints and bedding planes in the rock, the amount of water that can enter the tunnel is limited

• A study undertaken at the EIS stage determined that there was no groundwater dependent vegetation along the alignment

• Hyde Park in the Sydney CBD is a good example of tunnels existing below established vegetation. Shallow train and road tunnels run beneath Hyde Park for the City Circle and the Cross-City tunnels. These tunnels have not impacted the park’s Moreton Bay Fig trees

• Eligible residents will receive from this project an offer for one pre and one post construction property condition survey regardless of the number of tunnels under their property. If the section of the Western Harbour Tunnel is not the section being constructed by JHCPB, the WHT project will manage property condition surveys in accordance with the requirements of that project.

If at any stage you believe that damage has been done to your property from construction activity, please contact the project straight away via the community hotline at 1800 660 248 or email info@Rozelleinterchange.com.au

A. The Department of Planning, Industry and Environment is currently assessing The Crescent Overpass Modification. Transport for NSW is confident the Modification will meet the relevant criteria, however if the modification is approved, further consultation will be carried out on the Urban Design and Landscaping elements of the area affected.

Transport for NSW has announced the establishment of a Working Group to determine a range of factors relating to the Rozelle Parklands that are not covered in the UDLP. 

The NSW Government called upon community members to apply to be part of the Rozelle Parklands Working Group, alongside representatives from the NSW Government and Inner West Council. 

For further information on the Working Group members and how you can contact community representative, please visit here. Please contact RozelleParklands@transport.nsw.gov.au if you have any further questions.

A. The future parklands will be managed by Inner West Council and owned by Transport for NSW. This process is being finalised and is not part of the UDLP consultation.

Pedestrian and cyclist paths are shared within the parklands. The pedestrian and cycling implementation strategy within the UDLP provides connectivity between existing and proposed routes for local communities. It provides details of the pedestrian and cyclist routes which will be provided as part of the Rozelle Interchange project.

A. We are working with the Western Harbour Tunnel project team on the final location of this compound to minimise the impact. Please contactinfo.westconnex@transport.nsw.gov.au if you have any further questions.

A. Yes; the official name of the future parklands has not yet been determined.

A. The Rozelle Interchange project recognises air quality as a key community concern with most motorways. Projects such as WestConnex will help to reduce emissions and improve air quality by easing congestion across Sydney.

The tunnel ventilation system for WestConnex has been designed in line with the world’s best practice and meets strict guidelines on air quality. This includes tunnel designs which are wider, flatter and higher so ventilation works more effectively.

Based on the state-of-the-art design for WestConnex, filtration would not provide any measurable improvement to the air quality in the surrounding communities. Instead, communities along the WestConnex corridor stand to benefit from the removal of thousands of vehicles from local surface roads.

Ventilation outlets effectively disperse tunnel emissions and ensure there is minimal impact on air quality for local residents. No road tunnels in Australia use a tunnel filtration system.

Sydney’s air quality has improved significantly in the past 30 years. Total motor vehicle emissions have significantly fallen in the past 20 years as a result of improvements in fuel quality and better engine designs.

Videos and factsheets, including a section on filtration, are available on theTransport for NSW Air Quality portal.

A. The urban design component of the project will provide a major benefit to the Rozelle community. The provision of around 9.5 hectares of green space will allow connectivity from the new parkland at the old Rozelle Rail Yards to the Rozelle Bay, as well as opportunities for adding to the cultural identity of the precinct. The exhibition and feedback process enables the community to take part in creating this legacy. The UDLP is a design plan required by the Minister’s Conditions of Approval (E133 and E134). The document details aspects of urban design and landscaping the project is required to include in the UDLP.

As outlined in the Minister’s Conditions of Approval, the Rozelle Interchange Project must provide the development and delivery of public art opportunities throughout the Rozelle Rail Yards using local artists, however, this is not part of the UDLP consultation process. Please contactinfo.westconnex@transport.nsw.gov.au if you have any further questions.

The project will prepare an Operational Noise and Vibration Review (ONVR) to confirm noise and vibration control measures that would be implemented for the operation of the project. The ONVR will be prepared in consultation with the Department of Planning, Industry and Environment, relevant council(s), other relevant stakeholders and the community.

The ONVR does not form part of the UDLP and will be developed following confirmation of permanent design. Please contactinfo.westconnex@transport.nsw.gov.au if you have any further questions.

The Rozelle Interchange project will prepare a Water Reuse Strategy which sets out options for the reuse of collected stormwater and groundwater during the operation of the project. The Water Reuse Strategy does not form part of the UDLP and will be developed following confirmation of the project’s groundwater model. Please contact info.westconnex@transport.nsw.gov.au if you have any further questions.