The key changes to the tunnel alignment from the reference project include:

 relocating the east-west tunnels at Lutwyche and Wooloowin to accommodate changes to the design of surface connections
 increasing the depth and length of the east-west tunnels
 reducing the depth of the north-south tunnel to allow construction access from a shared worksite with the Northern Busway at Truro Street
 avoiding cut and cover tunnel through much of Lutwyche Road, the Department of Emergency Services and Kedron State High School
 changing properties affected by volumetric tenure, particularly in Lutwyche and Wooloowin.

What will the Project include?

The Airport Link Changed Projectis approximately 6.7km long, including about 5.3km of tunnels between Bowen Hills and Clayfield.

It includes:

• two separate north-south tunnels each up to approximately 30m underground and carrying three lanes of traffic in both directions between Windsor and Lutwyche
• two separate east-west tunnels each up to approximately 40m underground and carrying two lanes of traffic in both directions between Lutwyche and Clayfield
• surface connections at Bowen Hills/Windsor, Kedron/Lutwyche and Clayfield/Toombul, with transition structures at each connection to the surface
• a cut and cover tunnel under Kedron Brook linking Gympie Road and Stafford Road to the southbound and eastbound mainline tunnels
• a bridge across Kedron Brook linking the mainline northbound tunnel with Gympie Road and Stafford Road
• new interchanges and surface road improvements near the tunnel connections
• safety exits (cross-passages) at least every 120m, and fire protection and monitoring systems for tunnel users
• a longitudinal ventilation system to manage air quality in the tunnels and near the portals
• ventilation outlets at Windsor, Kedron and Clayfield
• urban design treatments and urban mitigation works in the project corridor.

Surface connections

The Airport Link Changed Project includes surface connections at Bowen Hills/Windsor, Lutwyche/Kedron and Clayfield/Toombul.

Bowen Hills/Windsor connection

The Bowen Hills/Windsor connection includes links to the Inner City Bypass, the North South Bypass Tunnel and the city and Fortitude Valley via Campbell Street and Lutwyche Road.

• Traffic heading north from the City or Fortitude Valley could connect to Airport Link from either Lutwyche Road or Campbell Street.
• Traffic heading north on the NSBT and east along the ICB could enter the Airport Link tunnel north of Enoggera Creek.
• Traffic heading south from Kedron and Toombul could leave Airport Link to connect to the:
• ICB to travel to the city and Hale Street
• NSBT to travel to Shaftson Avenue at Kangaroo Point, Ipswich Road at Wooloongabba or the Pacific Motorway (M3) at Wooloongabba
• Valley and the City via Campbell Street and Lutwyche Road

Key changes to the Bowen Hills/Windsor connection from the reference project include:

• a new connection from Lutwyche Road, north of Butterfield Street, including a new bridge over Lutwyche Road north of Enoggera Creek and an exit from the Airport Link tunnel to Lutwyche Road, north of Northey Street
• moving the southern ventilation outlet to the east near Byrne Street. This includes partially burying the ventilation outlet into a proposed land bridge connecting Mann Park to Lutwyche Road
• closing Federation Street and opening Gallway Street to provide access from Windsor East to Lutwyche Road
• changes to land requirements in Windsor East to include land between Federation Street and the extension of Gallway Street.

A detailed map of the Changed Project can be found here.

Kedron/Lutwyche connection

The connection at Kedron/Lutwyche includes links to and from Gympie Road and Stafford Road, and from Lutwyche Road to travel east to Toombul.

• Traffic heading south on Gympie Road or east on Stafford Road could connect to the southbound mainline tunnel in tunnel under Kedron Brook, to head to the city or Fortitude Valley, or the eastbound tunnel and travel to Toombul.
• Traffic heading north from the ICB, NSBT or the city and Fortitude Valley could leave Airport Link at Kedron to connect to the northern suburbs via Stafford and Gympie roads, or remain in the tunnel and travel east to Toombul.
• Traffic heading north along Lutwyche Road can enter the Airport Link to head east to Toombul.
• Traffic from Toombul could either leave Airport Link at Kedron connecting to Stafford and Gympie roads or remain in the tunnel and travel south.

Key changes to the Kedron/Lutwyche connection from the reference project include:

• realigning the mainline tunnels to the east of Lutwyche Road at Lutwyche
• rearranging connections with the mainline tunnels at Lutwyche to underground junctions east of Lutwyche Road and south of Kedron Park Road
• replacing some surface road and overhead road bridges with tunnels under Kedron Brook to link from Stafford Road and Gympie Road to the southbound and eastbound mainline tunnels
• keeping the Department of Emergency Services building Kedron Brook
• providing a drop-off and pick-up area in Lutwyche Road, adjacent to Wooloowin State School
• changing land requirements to include new volumetric requirements under the tunnels.

A detailed map of the Changed Project can be found here.

Clayfield/Toombul connection

The connection at Clayfield/Toombul includes links to and from Sandgate Road and the East-West Arterial.

• Traffic from the East-West Arterial could enter Airport Link to the east of Sandgate Road and travel west to Kedron or Lutwyche (via Stafford Rd) or remain in the tunnel to travel south towards the city or Fortitude Valley.
• Northbound and southbound traffic on Sandgate Road could enter the tunnel at Toombul and make these same connections.
• Traffic leaving Airport Link at Toombul could also travel north or south along Sandgate Road or continue onto the East-West Arterial.

Key changes to the Clayfield/Toombul connection from the reference project include:

• changes to the surface interchange at Clayfield, including shortening ramps from Sandgate Road
• moving the portals to the mainline tunnel to the west of Sandgate Road
• burying the Clayfield ventilation station building, reducing the height of the ventilation outlet from 30m to 25m and providing a substation south of the ventilation station on land fronting Sandgate Road.

A detailed map of the project reference design can be found here.

How will Airport Link be built?

Tunnel construction for Airport Link will involve a combination of driven tunnelling (underground tunnelling using a tunnel boring machine or roadheader) and cut and cover construction near surface connections, where the tunnel is close to the surface.

Drilling and blasting would also be necessary in some areas with hard rock or where particularly difficult conditions exist.

Key changes to tunnelling from the reference project include:

• launching the TBMs for the east-west tunnels at Clayfield rather than at Kedron. This will include constructing an underground TBM launch area in Kalinga Park and removing the TBM from the worksite at Chalk Street, Lutwyche
• constructing underground ramp connections to the mainline tunnels with roadheaders, including under Wooloowin State School instead of the cut and cover tunnels proposed on Lutwyche Road in the reference project
• constructing cut and cover tunnels from Stafford and Gympie roads under Kedron Brook to the mainline tunnels
• constructing part of the mainline tunnel from a shared worksite with the Northern Busway at Truro Street.

Construction work sites

Construction worksites are proposed at Windsor, Lutwyche/ Kedron and Clayfield/ Toombul. Access to the construction work sites is generally via major roads to avoid disrupting residential streets.

The construction worksites generally incorporate a range of measures to reduce construction impacts, such as noise and dust.

The key changes to the construction worksites from the reference project are outlined below.

Bowen Hills/Windsor

• increasing the Windsor worksite to include land west of Morris Street and Byrne Street
• extra worksites are provided at Windsor, on the western side of Bowen Bridge Road and at the intersection of Lutwyche Road and Northey Street, for construction the ramp over Lutwyche Road
• additional car parking is provided near Gennon and Addison Streets
• using the Northern Busway Truro Street worksite for Airport Link tunnelling

Lutwyche/Kedron

• using the Northern Busway Chalk Street worksite to remove the TBMs used to construct the east-west tunnels
• the worksite at Kedron State High School is no longer required for construction, but an area of the open space will be required as car parking for construction workers, with access from Gympie Road
• keeping the Department of Emergency Services building Kedron Brook as a site office.

Clayfield/Toombul

• increasing the worksite in Kalinga Park to allow the launching of the TBMs

Spoil removal

Approximately 2.8 M bank cubic metres (bcm) of spoil (rock and soil) will be removed during construction of the tunnels of the Airport Link Change Project. This is higher than the amount of spoil expected from the construction of the reference project, due to more driven tunnelling and burying the ventilation stations.
 
Approximately 340,000 bcm of spoil will be reused on site, including for the backfill of cut and cover tunnels, retaining walls and other earth bearing structures.

A further 520,000 bcm of spoil from TBM construction is proposed to be transported by conveyor, avoiding the need for approximately 80,000 truck movements.

Approximately 1.95 M bcm of spoil will be transported by truck, resulting in approximately 300,000 truck movements.

Spoil removal from work sites could occur 24 hours a day during the week and 12 hours a day on Saturday (i.e. 6.30am Monday to 6.30pm Saturday). This would allow truck haulage outside peak hours. Spoil haulage would not occur on Sundays or public holidays.

The following key changes to spoil removal from the reference project include:

• transporting spoil from TBM construction by conveyor from the Clayfield worksite under Sandgate Road, then transporting it to spoil placement sites by either conveyor or road
• options of additional spoil placement sites at Brisbane Airport
• providing extra routes for spoil haulage using Lutwyche, Gympie, Rode and Sandgate Roads and the East-West Arterial and Airport Drive.

How long will construction take?

The Airport Link Changed Project would take about 45-month to construct, with completion anticipated for late 2012.

Geotechnical studies

Geological testing within the study corridor has been undertaken to help the project team gain an understanding of the soil and geology within the study corridor.

Geotechnical testing was undertaken during the development of the reference project, which included more than 50 boreholes. This included an assessment of the potential impacts on properties over the proposed path of the Airport Link tunnels.

The geology of the tunnel alignment includes a combination of Tingalpa Formation, Brisbane Tuff, Neranleigh Fernvale Beds, Aspley Formation and alluvium.

Appropriate tunnelling has been selected for the different material.