Construction of the Serangoon North and Tavistock MRT stations on the upcoming Cross Island Line (CRL) is expected to start in the second quarter of this year.
This comes after the Land Transport Authority (LTA) awarded two related civil contracts with a combined value of $861 million.
LTA said yesterday that the contract for the design and construction of Serangoon North station and tunnels was awarded to Hock Lian Seng Infrastructure at a value of $454 million.
The station will be located under the busy dual lanes of Ang Mo Kio Avenue 3 and the Yio Chu Kang Road vehicular bridge. Traffic diversions will be implemented at various stages of the construction process to facilitate the building of the station.
Meanwhile, the underpass connection for the station will be constructed by mining beneath the Yio Chu Kang Road vehicular bridge. This will allow the construction of the underpass connection to be carried out without affecting the vehicular bridge, hence minimising the inconvenience to motorists, said LTA.
"LTA and the contractor will closely monitor the works to ensure that they are carried out safely with minimal impact to nearby stakeholders and existing structures," it added.
The Serangoon North station will have an additional third railway to facilitate the withdrawal or parking of trains.
LTA noted that Hock Lian Seng Infrastructure constructed the Kim Chuan Depot and Marina Bay station for the Circle Line, and is currently involved in the construction of Maxwell station along the Thomson-East Coast Line (TEL).
The authority awarded the second contract - for the design and construction of Tavistock station and tunnels - to Sato Kogyo at a value of $407 million.
The company constructed the Bencoolen and Mattar stations along the Downtown Line, as well as Upper Thomson station along the TEL.
The Tavistock station will be located along Ang Mo Kio Avenue 3 and surrounded by residential and commercial properties.
LTA said that to overcome space constraints, the intermediate launch shaft for the deployment of the tunnel-boring machines will be constructed a distance away from the construction site.
Tunnelling works will proceed west towards Ang Mo Kio station on the CRL as well as east towards the station at Serangoon North, passing through Tavistock station.
LTA also said that the ground at Tavistock station is made up of old alluvium, a predominantly soil-like material comprising sandy and silty clay. This is expected to cause some wear to the cutting equipment on the tunnel-boring machines.
"LTA and the contractor will pay close attention to the tunnelling equipment and overall works to ensure they are carried out in a safe and timely manner with minimal impact to existing structures," the authority added.
The first phase of the CRL (CRL 1), which is 29km long, is expected to start passenger service in 2030.
The CRL will be Singapore's eighth MRT line. It will serve existing and future developments in the eastern, north-eastern and western corridors, linking major hubs such as Jurong Lake District, Punggol Digital District and the Changi region.
There will be 12 stations in total in the first phase of the CRL from Aviation Park to Bright Hill.
This will serve residential and industrial areas in Loyang, Tampines, Pasir Ris, Defu, Hougang, Serangoon North and Ang Mo Kio.
CRL1 is expected to benefit more than 100,000 households.