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 new rail bridge over Kensington Road may be constructed to connect the new Metro Tunnel tracks to the southern side of the rail corridor.
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 is proposed 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.
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 are expected to commence in 2019. 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.
Prior to main works commencing, works to prepare sites for major construction will take place throughout 2017 and will be undertaken by the Early Works Managing Contractor, John Holland. In Kensington, this work includes relocation of the existing high voltage transmission towers along Childers Street.
Key construction activities
Key construction activities to build the western tunnel entrance would 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
- Construction of a new bridge deck over Kensington Road (subject to detailed design)
- 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).
During construction, Childers Street will be closed to traffic and used for construction activities. This will require the occupation of car parking spaces along Childers Street and the diversion of the shared use path along the railway line.
In addition to the temporary closure of Childers Street, the construction of the western tunnel entrance is expected to impact traffic and car parking on Tennyson and Altona streets during different stages of works.
Proposed construction traffic routes for the western tunnel entrance take advantage of the site's close proximity to CityLink and a number of major arterial roads. The proposed routes aim to move construction traffic away from local streets and on to these major connections as quickly as possible. South Kensington station will remain open during construction of the western tunnel entrance.
Alternative access to the station may be required during certain construction activities.
A number of rail occupations (periods where trains stop running so works can take place) will be required to connect the Metro Tunnel to the Sunbury line. These occupations would potentially disrupt services on parts of the rail network.
The construction contractors will be required to develop and implement measures to minimise disruption to the transport network during construction of the Metro Tunnel Project.