Construction work on the M4-M5 Link Tunnels Project - part of WestConnex - the Australia’s largest road infrastructure project - restarted from 31 July 2021, undertaken 24 hours a day, seven days a week.
In September construction has begun on a reinforced underground concrete structure known as a bridging slab in the M4-M5 Link mainline tunnels. The bridging slab will provide additional reinforcement where the Rozelle Interchange ramp passes over the mainline tunnels in Leichhardt.
Over 4500 cubic metres of concrete and 160 steel cages are required to complete the work. A prototype was recently developed and tested off-site before construction began underground.
The mechanical and electrical fit out teams on the M4-M5 Link Tunnels Project have taken over more than 12km of tunnel. The team have been busy installing fire and ventilation systems as well as lights, signs, fans and so much more.
The M4-M5 Link Tunnels team started tunnelling from the Northcote Street tunnelling site in mid-2019 and from the Pyrmont Bridge Road tunnel site in May 2019. Excavation has now progressed beyond Hawthorne Canal.
Throughout October 2021 work will continue:
• east beyond Norton Street, Leichhardt with excavation of the top of the ramps (heading) begin below Norton Street, Derbyshire Road and Pioneers Memorial Park in Leichhardt;
• in the Annandale and Leichhardt areas with drainage activities in the vicinity of Whites Creek Lane and Mayes Street, as well as in the vicinity of Coleridge Street and Waratah Street, Leichhardt.
The tunnel is being excavated in several stages:
- Stage 1 - excavating the top of the tunnel and cross passages, called the heading, and installing support including large steel bolts into the rock and sprayed on concrete;
- Stage 2 - excavating the lower half of the tunnel, called benching;
- Stage 3 - excavating drainage channels with saw cutters, a trenching machine, and jackhammers. Stage 3 is done in sections following the tunnel excavation.
The tunnel is excavated using roadheader machines (Stage 1 and 2). In areas of hard sandstone rockhammers may also be used. After the completing the benching, drainage channels are dug using a trenching machine and where required, jackhammers (Stage 3).
Back in April 2021 a major milestone was reached for the M4-M5 Link Tunnels Project, with roadheaders smashing through sandstone to connect two sections of tunnel for the first time. The breakthrough connected westbound sections of the mainline tunnels between St Peters Interchange and Annandale, which is about 50 m below Newtown: more than 90% of the twin 7.5km tunnels between the M4 corridor at Haberfield and the M5/M8 corridor at St Peters and ramps was excavated, with just 2km left to excavate.
With more than 100,000 trips a day expected on the M4-M5 Link Tunnels, communities above ground in Sydney’s Inner West will benefit from reduced traffic and congestion on suburban streets, returning them to local communities. There have been 450 contracts signed with NSW subcontractors and suppliers to the value of more than EUR 596,54 (AUD950) million. For further information please click here and au/13 for the tunnelbuilder archive reports on the project.. Visit https://www.westconnex.com.au/. 40/21.
