You are on PERI's international website. Click here to switch to PERI USA. Click here to view all PERI websites.

Sydney Metro Northwest - Castle Hill Cavern

Project data

Location: Sydney, Australia

The $8.3billion North West Rail Link project is the longest transport tunnelling project in Australia’s history and is expected to be complete by 2019. The 15 km long twin tunnels are being constructed to connect Sydney’s northwest suburbs to the city for the very first time.


The Cross Over Cavern at Castle Hill is an nominally 20.5 m wide and 159 m long cavern opening up from the eastern side of the station box, which consist of two parts:

  • A lower cross section with 14m height over about 131m length
  • A higher cross section with 17.5 m height over about 25 m length

And a 2.5 m long transition section between these parts

The cavern finishes with a headwall from where it connects to two smaller stub tunnels.

The 500 mm thick cavern lining is reinforced up the construction joint above the lower wall.

The walls and crown lining above this level is unreinforced.

The between 800 mm and 1200 mm thick headwall is completely reinforced


Thiess John Holland Dragados JV

Benefit to customer

  • Quick setup, and moving of the entire assembly using the Variokit traveller.
  • Fast pouring rate
  • High surface quality
Will Freeland
Project Manager

The assistance provided by PERI in coordinating the design requirements, the methodology and subcontractor suggestions, was integral to the success of the project.
When assembled onsite the mechanical nature of the form removed many manual handling and work at height risks, whilst the drive units allowed the unit to be propelled in a safe and timely manner, allowing further safety and program improvements.

PERI solution

  • PERI SB for Wall formwork for the lower walls between the invert and the construction joint at TBM tunnel centre level (2 numbers, one for either side of the wall).
  • PERI VARIOKIT for formwork for the upper lining in the standard and enlarged cross over cavern sections.
  • Combination of PERI SB, VARIOKIT and Rosett systems for the headwall.
  • Specially fabricated components for the entire system.
  • The PERI UP Rosett Flex system for providing access to various areas of the formwork
  • The tunnel formwork measures a staggering 20m in width with heights varying between 14m and 17m
  • Using VARIOKIT traveler to move the massive 140 ton tunnel formwork system
  • Supplying tunneling formwork for “nozzles” at Bella Vista, Norwest, Showground and Epping Stations