1,000 t

of CO2 avoided

4.25 km tunnels in Brisbane

The project, developed by a consortium led by ACCIONA, has helped to shape a road system around Brisbane, reducing a journey time of twice as long to 14 minutes with minimal impact on the local habitat. The aim was to improve traffic and connections with metropolitan areas and the airport in Brisbane, Australia's third largest city.

It involved the construction of the Legacy Way tunnel and the toll road connecting the western Toowong highway to the city centre. The project involved the design, construction, operation and maintenance (for 10 years) of 4.25 km twin road tunnels, with an outer diameter of 12.4 metres (11.3 m internal diameter) in an urban environment. The tunnels created a bypass connecting the western highway in Toowong to the Inner City bypass in Brisbane.


Construction of the tunnel included 2 access shafts, 2 ventilation stations, 36 crossing galleries, 2 underground and 2 surface substations, and 1 low-rise sump. The tunnel portals were excavated using top-down construction methods, whilst other areas were excavated using conventional methods.


  • Location: Brisbane, Queensland, Australia.
  • Contract: Design, construction, operation and maintenance (PPP) for 10 years.
  • Infrastructure: 8.6 km of motorway in twin parallel tunnels, 4.60 km long and with an outer diameter of 11.30 metres of lining. Built with double shield TBMs, one of which achieved a world record excavation record.
  • Year of project completion: 2015


The following were shown during project implementation, among other things:

  • Excellent and recognised management of a wide group of stakeholders in an urban environment.
  • Conservation of a publicly sensitive area of cultural heritage.
  • Effective and innovative management of waste and noise impacts on the community.
  • A complex network of government and community stakeholders, including a large high school and botanical gardens on site.

Key figures


tonnes of CO2 avoided


avoided trips


Australian and international awards

Awards and recognitions

The project won five Australian and international awards and set world records for the TBM's daily, weekly and monthly progress. The first TBM breakthrough happened four months ahead of schedule, and the second six months ahead of schedule. The awards that it won are:

Technology and innovation

Innovative tunnel engineering, design, and construction methodologies and processes were implemented, including:

  • A tunnel shell ensures minimal movement between segments at the base of a universal geometry ring
  • Development of reinforced steel fibre (RSF) segments as standard application in large diameter rock tunnellers
  • Development of a design solution for the installation of an anti-roll over system in the launch slab to compensate for the resulting torque of the cutting units
  • Development of a design solution for a steel ring that acts as a reaction structure required for the erection of the first complete ring


To ensure compliance with environmental legislation throughout implementation, the JV developed and launched a comprehensive Environmental Management Plan (EMP) that minimised, monitored, managed and mitigated the impacts of construction activities.

This includes a comprehensive monitoring programme for noise, vibration, air and water quality. The joint venture built a 7-storey acoustic shed on the Western Portal to mitigate the impact of noise in the area.

Another innovative approach to environmental problems is the commitment to dispose of waste using an underground conveyor belt. A conveyor belt is used in each tunnel, plus a joint transversal belt for the continuous transport of excavated material from the tunnels to the Mount Coot-tha quarry. This joint belt is 870 m long, of which 560 m are underground, thus reducing by a little less than half the length of the journey of the materials excavated in the original project. This design of debris removal and reuse in the recovery of an old quarry proposed by the Customer Consortium has been the foundation of one of Brisbane City Council's awards for innovation in the Environmental Mitigation category of the International Road Federation Global Road Achievement Awards 2014 (GRAA).

During the tunnel construction period, the emission of 1,021.37 tonnes of CO2 was avoided thanks to the solution chosen for the waste disposal, which avoided 187,257 trips. In addition, noise in the work area was reduced and the impact on local vegetation resulting from pollution and dust decreased.

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