North West Rail Link Project – Sydney

Project Type: Design & Construct

Owner: Transport for New South Wales

Construction Cost: AUD 1.15 Billion

Contractor / Client: Thiess – John Holland – Dragados JV

Design Period: 2013 – 2015

Construction Period: 2013 – 2017

 

The Project

The Tunnel and Station Civil Works contract for the Northwest Rail link project which has been awarded to the Thiess-John Holland-Dragados JV, includes the construction of 15km twin segmentally lined tunnels between Bella Vista and Epping. Additionally, the project also includes the civil works construction for five of the eight new stations, namely Bella Vista, Norwest, Showground, Castle Hill and Cherrybrook and two service facilities at Cheltenham and Epping.

The tunnels range in depth from 5m-70m below ground level but are typically 20m-25m deep. The internal tunnel diameter is 6.17m. In total 4 hard rock gripper TBMs are used to construct the majority of the tunnel works. To satisfy fire and life safety requirements cross passages at regular intervals of about 240m are provided for emergency access.

For the construction of the crossover caverns, stub tunnels linking the new tunnels to the existing Epping to Chatswood tunnels and the cross passages roadheaders are used. The crossover cavern at Castle Hill is approx. 160m long and 23m wide. Most of the cavern is 14m high. However, for 30m the height increases to 17m to allow for mechanical equipment to be installed.

The alignment requires about 60% of the alignment to be excavated in Hawkesbury Sandstone and the remainder is excavated through Ashfiled Shale with varying strength.

Key Aspects

• 15 kilometers of twin segmentally lined bored tunnels
• Excavation and civil works for five stations at Bella Vista, Norwest, Showground, Castle Hill and Cherrybrook
• Excavation and civil works for service facilities at Cheltenham and Epping
• Geology comprises of Ashfield Shale, Hawkesbury Sandstone
• Excavation by four hard rock gripper TBMs
• Pre-cast concrete lining segments: 5 segments, inner diameter 6.17m, 260mm segment thickness
• Mined cross passages every 240m
• Mind crossover cavern at Castle Hill with a length of 160m and a width up to 23m

Scope of Works

NOMA Consulting was engaged by TJHD JV to carry out the detailed design of the following aspects:

• Independent design review of mined Castle Hill cross-over cavern
• Detailed design of pushing frames for all stations
• Detailed design of TBM cradles, segment support bracings and launch seals
• Detailed design of alternative launch frame using anchors for launching at the portal the of nozzle tunnel
• Construction support to address construction related issues and design modifications