Western tunnel entrance construction plans
Building the western tunnel entrance
Building the western tunnel entrance will involve construction works on Childers Street to build a retaining wall that will support the embankment on the northern side of the rail corridor (east of Kensington Road), which is to be widened to accommodate the new Metro Tunnel tracks.
A decline structure will be built so trains can enter the new Metro Tunnel.
The tunnel entrance structure is proposed to be built via a 'cut and cover' method, which will see them excavated from the top down and the surface then reinstated over the top of the tunnels.
A construction support site on Hobsons Road and a tunnel boring machine (TBM) retrieval box will also be built to support tunnelling works.
It is not proposed that any construction activities for the Metro Tunnel Project will be undertaken in JJ Holland Park, other than potential upgrades to the shared use path.
Major construction on the Metro Tunnel has commenced in Kensington.
During September works activities include:
- Ongoing site establishment activities
- Site and service investigations
- Detour route modifications on Kensington Road, Derby and Tennyson streets
- Temporary road realignment works on Lloyd Street
- Constructing a temporary roundabout at the intersection with Ormond Street
- Relocating the existing pedestrian crossing to the east of the temporary roundabout location.
Piling will be undertaken in two stages from mid-September and the end of 2018 to construct the walls of the TBM retrieval shaft.
The first stage will commence in mid-September, adjacent to the rail lines on the southern side of Childers Street. This will include:
- Constructing a pile guide wall
- Using piling rigs to drill holes approximately 22 metres deep
- Lifting steel cages into the drilled hole
- Pouring concrete into the hole to create the pile
- Breaking back the top of the pile once the concrete is set using jackhammers
- Constructing a concrete pile beam that links the installed piles
- Up to 50 truck movements per day to support piling activities.
In total, approximately 110 piles will be installed within the Childers Street worksite.
These works may generate intermittent periods of low to medium level noise and vibration. These works will be undertaken during normal construction hours only.
During September 2018, we will be undertaking investigations to confirm the location of underground utilities within the project area.
This will involve using non-destructive digging (NDD) to locate services at a number of locations within and in proximity to the Childers Street worksite, and on Lloyd Street.
These works may generate periods of medium to high noise during NDD activities.
The speed limit on Lloyd Street adjacent to the work areas will be reduced to 40 km/h during work hours.
Traffic flow on Lloyd Street will be maintained in both directions under a shuttle flow arrangement.
The surface will be reinstated once each location has been completed.
Investigations are expected to take approximately one day at each location.
Site investigations will be undertaken on Childers Street and within the rail corridor to better understand local ground conditions and assist with the planning and design of the western tunnel entrance in Kensington.
This will include:
- Undertaking additional geotechnical investigations along Childers Street and within the rail corridor.
- Non-destructive digging, which involves using a vacuum truck to excavate carefully into the ground to confirm an area is free of services.
- Geotechnical drilling to determine existing ground conditions. This involves drilling 100-millimetre diameter boreholes up to a depth of approx. 30 metres.
- Cone penetration tests, which involve pushing a cone tipped rod into the ground to test conditions.
- Installing groundwater monitoring wells in some locations to allow sample collection and measurement of groundwater levels.
These works are expected to be low impact, however there will be some high-level noise generated when non-destructive digging is taking place.
The noise generated by geotechnical drilling will be similar to that of a truck with its engine idling.
These activities will take place within the rail corridor and up to nine parking bays on Childers Street. Traffic controllers may be in place for short durations at various times to assist mobilisation and demobilisation of vehicles and equipment.
Detour route modifications
While Childers Street is closed to through traffic, cyclists will be detoured through Altona Street.
There will also be limited periods during construction where it is not possible for over-height vehicles to access the Lloyd Street Business Estate through the Childers Street worksite. During these limited periods, a detour via Derby and Tennyson Streets will be used, with reduced speed limits and traffic controllers in place.
Works are required to prepare these detour routes for use, see details below the map.
At Kensington Road, we need to remove the traffic islands on either side of the Derby Street intersection, reseal the roads and install new line marking.
What to be aware of
- There will be periods of loud noise associated with road cutting and asphalting works.
- The speed limit will be lowered to 40 km/h between Cairncross Lane and Epsom Road.
- Eight on-street parking spaces on Kensington Road will be occupied during works.
- Traffic flow will be maintained in both directions via a shuttle flow arrangement.
To provide a detour for cyclists, we need to widen the footpath at the Altona Street truncation to create a shared-use path.
What to be aware of
- Non-destructive digging (NDD) will be undertaken to locate and protect tree roots prior to works commencing.
- The path will be widened and small ramps installed to connect the road to the shared-use path.
- The new path will be line marked.
- There is expected to be periods of loud noise associated with non-destructive digging and path installation.
- Car parking on Altona Street will not be impacted by these works.
- Restricted access to vehicles through the modified truncation will be maintained.
- Please obey signage and traffic controllers during these works.
At Tennyson Street, we need to level the surface of the road at the existing truncation and install movable barriers to ensure the road remains closed when the over-height vehicle detour is not in use.
What to be aware of
- The road will be resealed and new line marking installed.
- There is expected to be periods of loud noise associated with road levelling and asphalting activities.
- Up to six on-street parking spaces on Tennyson Street will be occupied during these works.
- Temporary narrowing of the cycling lanes either side of the existing truncation during works will be required. Cyclists are advised to obey signage and traffic controllers in the area.
- Some trimming of branches that overhang the road may be required. No trees will be removed along Tennyson Street.
Some tree trimming may be required along Derby Street to facilitate the safe detouring of over-height vehicles accessing the Lloyd Street Business Estate. These clearances have been recently surveyed and this information is currently being assessed by our traffic and environmental teams.
To enable construction of the temporary roundabout, the truncation at the southern end of Ormond Street will be moved approximately ten metres north of its current location.
This is to ensure Ormond Street remains closed at Childers Street during construction.
What to be aware of
- Kerbing will be installed to create the new section of truncation
- There is expected to be periods of loud noise associated with road cutting and asphalting activities
- Footpaths will be realigned to cross over the modified truncation
- Part of the southern section of the existing truncation will be removed as part of temporary roundabout construction
- Three on-street parking spaces may be impacted during these works
- Two parking spaces will be removed as part of this modification.
Given the scale and complexity of the project, works to build the Metro Tunnel Project will be delivered via a series of packages. Each package of works will focus on different elements of the Metro Tunnel.
The exact design of the western tunnel entrance may continue to evolve as we work with potential contractors ahead of contract award. Major works to build the western tunnel entrance will commence in 2018. It is estimated that construction of the western tunnel entrance will take around three years.
After the main civil works are complete, the entrance is anticipated to be used by contractors to fit out the tunnel for approximately another two years.
Key construction activities
Key construction activities to build the western tunnel entrance will include:
- Preparatory works including the protection and removal of a limited number of trees on Childers Street, and relocation of utilities including the electrical high voltage transmission towers.
- Demolition of one residential property.
- Temporary relocation of public car parking and the shared pedestrian and cyclist path on Childers Street
- Construction of the TBM retrieval shaft.
- Widening of the rail reserve to accommodate additional tracks and install retaining walls alongside Childers Street.
- Cut and cover excavation of the tunnel entrance structure.
- Track works and the installation of signalling and communications systems.
- Site reinstatement including upgrading the shared pedestrian and cyclist path, altered parking and road layout and landscaping.
- Tunnel fit-out (installation of track, overhead line equipment and services).