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Award-winning designs, Eastern Distributor tunnel, Sydney, Australia


The Eastern Distributor is a 6 km, two to three lane motorway linking northern, southern and eastern Sydney and providing access to Sydney Airport. The 1.7 km of tunnels running from Woolloomooloo to Surry Hills are situated beneath densely-populated urban areas.

PSM was engaged to design the temporary and permanent supports for the tunnels as well as map and monitor the tunnel excavation.

engineering AND technical opportunities

The tunnel design needed to accommodate three lanes northbound and three lanes southbound while minimising land take within a constrained space in densely populated urban surroundings.

Specific engineering and technical opportunities included:

  • Tunnelling underneath the road stratum of Bourke Street, Sydney without encroaching on closely abutting private land
  • Accommodating the Woolloomooloo fault zone and the Great Sydney Dyke
  • Creating a design solution to accommodate the main Bondi Ocean Outfall Sewer (BOOS) which is within the construction area.

approach AND innovation

Following a rigorous assessment and modelling, PSM’s award-winning approach included:

  • Design of a unique double-decker carriageway to allow for three traffic lanes travelling in both northerly and southerly directions, with the upper carriageway resting on a rock ledge of Sydney sandstone being a world first
  • Design of 24.5 m x 14 m tunnel at its widest point
  • Development of a specialised rock bolt with corrosion protection recognised for a 100-year design life
  • Full integration of geotechnical experts with the construction team to ensure flexible, efficient solutions-focused communications between designers and construction.


  • Winner, Sir William Hudson Australian Engineering Excellence Award 2000
  • Winner, Institution of Engineers Australia Bradfield Award for Engineering Excellence 2000


Successfully completed within the contracted timeframe, PSM developed an innovative design that met the scope of work’s technical and commercial challenges.

Services: #Award Winning #infrastructure #Tunnelling

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