Construction of the M4-M5 Link

Subject to planning approval, the M4-M5 Link would be constructed and opened to traffic in two stages:

  • Stage 1: Construction of the mainline tunnels is anticipated to start mid-2018 and open to traffic in 2022
  • Stage 2: Construction of the Rozelle interchange and Iron Cove Link is expected to start in late 2018 and open to traffic in 2023

Building the project in two stages will allow for the mainline tunnels to operate independently (initially with 2 lanes in each direction) prior to the completion of the Rozelle interchange and the Iron Cove Link, delivering key benefits of WestConnex to road users and local communities sooner.

A detailed breakdown of the key elements included in each stage of construction is available in Chapter 6, Section 6.1.2, of the EIS.

Construction activities

In addition to below ground works, surface works would be required to support tunnelling activities and to construct surface infrastructure.

These activities are summarised in Chapter 6, Section 6.4, of the EIS.

Site establishment

  • Site establishment would occur before major construction work starts, and take approximately 3 to 12 months, depending on the extent of the work involved at the respective location. An indicative construction program for each site is outlined in the Community Guide to the EIS as well as in Chapter 6 Sections 6.5.2 to 6.5.14 of the EIS.
  • It typically involves building support facilities such as offices, amenities and workshops; demolition work; clearing vegetation; removing or installing utilities; constructing internal roads and vehicle access points; and establishing noise barriers, acoustic sheds and fencing.


  • Constructing the M4-M5 Link would involve excavation for two mainline tunnels, each 7.5 kilometres long; the Rozelle interchange; and the Iron Cove Link, as well as tunnels providing connections, ventilation and temporary access for construction.
  • Tunnels would most likely be constructed in sections. Excavated material, also known as spoil, would be brought to the surface, loaded onto trucks and disposed of at approved sites.  

The Spoil Management Strategy is described in Chapter 23 of the EIS.

Surface works

  • Construction of tunnel portals, as well as tunnel support facilities, would take place above ground and generally during standard construction hours.
  • Surface works would include drainage and utilities installation; construction of support facilities and bridges; and roadworks. Construction would be subject to careful traffic management to maintain the functionality of surrounding roads, and keep the public, motorists and construction workers safe.      

Further details on proposed construction hours at each site, including the type of construction activity that would take place, can be found in Chapter 6, Section 6.7.2, of the EIS.

Hours of operation

Above ground construction work would be carried out between the following standard construction hours:

  • 7am to 6pm Monday to Friday
  • 8am to 1pm Saturday
  • Generally, no work on Sundays or public holidays
  • Where work is required outside of these hours it would be conducted in accordance with conditions of approval and Environment Protection License conditions

Tunnelling work

Tunnelling work, including spoil haulage and delivery, would be carried out 24 hours a day, seven days a week

Building tunnels

WestConnex motorway tunnels are designed to be wider, flatter and higher than most other tunnels in Sydney, resulting in a smoother journey and fewer vehicle emissions – including greenhouse gases. 

The tunnels would be mainly constructed in good quality Hawkesbury sandstone, with short sections near portals constructed in Ashfield shale.

Stage 1: Excavation

  • The top section of tunnels (the heading) would be excavated using roadheaders – specially-designed excavation machines with rotary cutters, positioned on bulldozer-style tracks. Approximately 20-25 metres of tunnel is expected to be excavated per week.
  • The bench (lower section of the tunnel) in the mainline tunnels could be excavated using either rock breakers or by controlled blasting. If blasting is proposed, a Blast Management Strategy would first be prepared in accordance with relevant noise and vibration guidelines.  
  • The excavated material would be removed by trucks for disposal or reuse. Where practical, this would take place during the day, outside of peak periods.
  • Rock-bolting (to stabilise the tunnel interior), shotcrete (a method of concreting), and the tunnel lining would be installed progressively as excavation advances.

Stage 2: Finishing works

  • Finishing works would begin once tunnel excavation is complete. This would include the installation of stormwater and groundwater drainage systems; pavement construction and line-marking; painting; and installation of electrical pipes, road signage, street lighting and electrical panels.

Stage 3: Fitout

  • Tunnels would be fitted out with operational infrastructure. This would include power; lighting; and systems to support ventilation, fire safety, tolling and traffic control.
  • The tunnel would go through an extensive testing process before it opens, to ensure it is fully operational and integrated into the broader road network.

Protecting property

  • To provide peace-of-mind to local residents and businesses, all properties within 50 metres of the outer edge of the underground tunnels will be offered a property condition survey before construction, with a follow-up survey (for the property) after construction.
  • In the unlikely event there is any damage attributed to the project it would be repaired at no cost to the property owner.

Further detail on tunnel construction, including methodology and equipment, can be found in Chapter 6, Section 6.4.2, of the EIS.