WestConnex New M5

The New M5 seeks to provide twin underground motorway tunnels to alleviate congestion and support Sydney’s long term economic and population growth. The project is valued at 4.34 billion and will be 9 km long, located from Kingsgrove to the new St Peters interchange.

Large part of the project took place within a tunnel. Challenges include having stable working platform to install support beams for structural integrity of the tunnel. As the ground was found to have silica dust, the use of imported fill became untenable. The silica dust had the potential to contaminate the gravel and any time a vehicle drove over the ground, toxic substances would have been released into the air. Workers therefore had to monitor air quality and wear protective equipment the entire project.

As an engineering control, Dura-Base mats were used to suppress dust and minimise the risk of exposure to crystalline silica. Safeguarding the workers from life threatening diseases caused by the crystalline silica.

The thick 105mm interlocked mats served as a temporary access and used to stabilise the ground for for an SPMT to install horizontal beams. Uneven ground would have resulted in the machine unable to gain entry in the tunnel due to the unstable ground.

Once the installation was complete, the workers had to excavate another level down to install more beams. The mats were easily removed and reinstalled down afterwards. Preferable to imported fill as it would have increased the amount of truck movements and would require copious amount of time to retrieve.

The mats were reused at both the Western and Eastern End of Tunnel. Once the beams were installed, the mats could be picked up without disturbing the underlying ground containing silica.