Airport Link and Northern Busway Project – Brisbane

Project Type: Design, Construct & Maintain Alliance

Owner: Brisconnections / City North Infrastructure

Construction Cost: AUD 4.8 Billion

Contractor: Thiess – John Holland JV

Client: Parsons Brinkerhoff-Arup JV

Design Period: 2008 – 2011

Construction Period: 2008 – 2012

 

The Project

The Airport Link is a 6.7 kilometre toll road, mainly traveling underground. It connects the CLEM7, the Inner City Bypass and the local road network at the south to the northern arterials at Kedron and the East West Arterial leading to the airport. The Airport Link consists of 5.1km twin tunnels, with entry and exit portals at Bowen Hills, Kedron and Toombul. The project also includes the construction of the 3km Northern Busway (Windsor to Kedron) featuring a 1.0km busway tunnel which is located directly above the Airport Link tunnels. Additionally the Airport Roundabout Upgrade replaced the old signalised roundabout with a 750m Airport Flyover, linking the East West Arterial with Airport Drive, and a high capacity “fast diamond” intersection.

Key Aspects

• Twin mined and bored road tunnels with several on an off ramps with a total length of approx. 15km
• Very strong rock such as volcanic Brisbane Tuff, argillites and phyllites called Neranleigh Fernvale down to very weak siltstones with ash (clay) bands and quaternary alluvium
• Excavation by road headers, drill & blast and earth pressure balanced (EPB) TBMs.
• Pre-cast concrete lining segments: 9 segments, 1 key, inner diameter 11.34 m, 400mm thick and 2.0m in width
• 41 cross passages and several cross cuts along alignment
• Separate busway tunnel with a length of 1km and a width of 16m being located closely above the constructed APL mainline tunnels
• 2 x 12.4m diameter TBMs & 17 roadheaders including drill & blast excavation
• Toolbox design approach; i.e. providing a number of support types
• Several major cut & cover structures at Bowen Hills, Kedron and Toombol
• Elevated ramps linking the tunnel to existing roadwork and Clem 7 tunnel (Southern Connection at Bowen Hills)
• 750m long segmental flyover at airport roundabout
• 25 bridges – the tallest being 25m high and the longest being 684m

Scope of Works

NOMA Consulting was engaged by PBA JV to lead the detailed design of the mined tunnels at Kedron and to provide support to other design teams as listed below:

• Detailed design of temporary support requirements for all mined tunnels
• Assessment of surface settlements due to mined tunnel excavations
• Specification of instrumentation and monitoring requirements for tunnel works
• Design of mined tunnel including 3D modelling of Westbound off and Southbound on-ramps with cut & cover structure TW930
• Design of stitched rock pillar using rock anchors at bifurcation area between main line tunnels and ramps at Lutwyche caverns
• Design of cross passages for bored tunnels between Kedron and Toombool
• Design of ‘flying’ launching arrangement for re-launching TBMs within Kedron caverns
• Design support to designer’s construction supervision team
• Review of instrumentation and monitoring results and attendance of meetings in case trigger values were exceeded
• Assessment of loads imposed on permanent tunnel linings