SINGAPORE - Tunnelling works for Circle Line 6 (CCL6) - the final stage of the orbital Circle Line (CCL) - started on Thursday (July 25) with the launch of a tunnel boring machine at Keppel station.
The Land Transport Authority said it will tunnel from Keppel to the existing HarbourFront station. Two other tunnelling machines are expected to be launched in September and October this year.
The LTA said work on CCL6 is progressing on track, with 66 per cent of earth retaining and stabilising structure works being completed.
"Excavation works and construction of structures have also commenced and are progressing well," it noted. "Foundation and excavation works are also in progress at Kim Chuan Depot Extension."
The expanded depot will provide additional facilities to support the larger CCL network and up to 133 trains. It will also have an above-ground bus depot which can accommodate 550 buses.
LTA said on Thursday it is also buying 12 new trains from French supplier Alstom to cater for the expected increase in passengers. These trains will be delivered progressively from 2024, and are in addition to the 11 trains that were procured in April 2018 for CCL6.
When these 23 trains are delivered, the total CCL fleet size will increase by 36 per cent to 87.
Meanwhile, works are under way to upgrade the CCL to prepare for the opening of CCL6 in 2025.
The LTA said it is working with operator SMRT on a series of system enhancements to the existing CCL.
The enhancements will allow the decade-old CCL to support, among other things, a larger train fleet when three new stations along CCL6 open.
The upgrades include the line's signalling system; power supply system (including installing a load break switch at substations to help maintain continuity of power supply should there be a power outage); and communications system to allow more seamless real-time communication between individual stations and the Operations Control Centre.
This will strengthen SMRT's oversight of the entire CCL system, the LTA said.
LTA chief executive Ngien Hoon Ping said: "As we are working on a 'live' railway system, we will work closely with SMRT to put mitigating measures in place to ensure daily operations will not be impacted."
Most of the work will be done during non-operating hours.
SMRT chief executive Neo Kian Hong said it was "essential that we start the renewal process early and apply the lessons learnt from the renewal of the North-south and East-west lines".
The LTA said construction of the three CCL6 stations - Keppel, Cantonment and Prince Edward Road stations - and the expansion of Kim Chuan Depot are on track.
When CCL6 opens, the entire orbital line will have a total of 33 stations with 12 interchanges to connect to all existing MRT lines and the future Thomson-East Coast Line. The stations will also close the loop for the CCL by connecting HarbourFront Station to Marina Bay Station.