SINGAPORE: Major tunnelling works that allow passengers and baggage to travel between Terminal 2 (T2) and Terminal 5 (T5) at Changi Airport have been completed, Changi Airport Group said on Wednesday (Dec 31) as it gave more details of the engineering feat.
In total, there are three 1.7km long tunnels that lie underneath one of the airport runways. Two of the completed tunnels are meant to transport passengers between the existing airport and the Changi East site through automated people movers, while one tunnel is for baggage.
The people movers will be similar to the current Skytrains.
"(The) tunnels enable Changi Airport to operate as a single integrated airport," said Dr Wen Dazhi, who is a senior vice president with Changi East Construction.
Boring works began in January 2022 and were completed in December that year, and the whole project was certified completed in October 2024.
With an excavated diameter of 12.3m, the tunnel for baggage is the biggest bored tunnel in Singapore at the time of construction, said Dr Wen.
The main challenge was to make sure that the disturbance to the surface was minimal, to ensure that airport operations would not be affected, especially when tunnelling under a live taxiway, he added.
With the major tunnelling works for the 1.7km stretch completed, all that is left for the tunnel project are additional construction works to connect the tunnels at both ends to the two terminal buildings.
At T2, a basement is being excavated for the construction of a baggage handling system, as well as a station and depot for the trains that will travel through the tunnels between T2 and T5, said Dr Wen.
T5, which broke ground in May, is scheduled for completion in the mid-2030s, enabling Changi Airport to serve about 50 million more passengers annually. It will house a dedicated ground transportation centre – integrating train, bus, taxi and other transport services in one location.
A worker seen next to a pair of automated people mover tunnels, which will be used to link passengers between terminals, below the ground at Changi Airport's Terminal 5 construction site, Dec 30, 2025. (Photo: CNA/Wallace Woon)
A view of the opening of an automated people mover tunnel, which will be used to link passengers between terminals, 28 metres below the ground at Changi Airport's Terminal 5 construction site, Dec 30, 2025. (Photo: CNA/Wallace Woon)
An automated people mover tunnel, which will be used to link passengers between terminals, below the ground at Changi Airport's Terminal 5 construction site, Dec 30, 2025. (Photo: CNA/Wallace Woon)
Workers walking through an automated people mover tunnel, which will be used to link passengers between terminals, at Changi Airport's Terminal 5 construction site, Dec 30, 2025. (Photo: CNA/Wallace Woon)
Lowering of the tunnel boring machine parts into the launch shaft for assembly. (Photo: Changi Airport Group)
Changi Airport Group had previously announced that there would be a separate people mover service between T5 and T2 via a 2.5km underground link between the terminals, which began construction in 2024.
A fleet of five trains will carry passengers between T2 and T5, with two operating at each time. Each train can carry up to 96 passengers and their bags, and a one-way journey will take about four minutes.
As for the baggage handling tunnel, Dr Wen said it will be able handle up to 3,000 bags per hour.
For now, a conveyor belt has been installed in the baggage handling tunnel to transport excavated soil from the ongoing construction at T2 to T5 for easier disposal, since T2 is an operating airport environment, said Dr Wen.
Typically, excavated earth has to be transported away using trucks, which could lead to congestion at the airport. The conveyor belt system has eliminated this issue, he added.
T5, built on a plot of land about 20 per cent bigger than Toa Payoh, will have three different parts also connected by a separate line of people movers, while its location could pave the way for air-sea transfers via Tanah Merah Ferry Terminal.
When the first phase of the T5 project is completed in the mid-2030s, it will be able to handle about 50 million passengers annually. Changi Airport’s existing four terminals now have a 90 million passenger capacity.
A new MRT station at T5 will serve as an interchange station connecting the airport to the Thomson-East Coast Line and Cross Island Line. At T5, two more tunnels that will connect to the future MRT station are being built, said Dr Wen.
The new station will be part of the Thomson-East Coast Line extension, which will provide a direct rail link between Changi Airport and the city centre, to areas such as Gardens by the Bay, Maxwell and Orchard.
Changi Airport will be connected to neighbourhoods such as Ang Mo Kio, Hougang, Punggol and Clementi via the Cross Island Line.
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In total, there are three 1.7km long tunnels that lie underneath one of the airport runways. Two of the completed tunnels are meant to transport passengers between the existing airport and the Changi East site through automated people movers, while one tunnel is for baggage.
The people movers will be similar to the current Skytrains.
"(The) tunnels enable Changi Airport to operate as a single integrated airport," said Dr Wen Dazhi, who is a senior vice president with Changi East Construction.
Boring works began in January 2022 and were completed in December that year, and the whole project was certified completed in October 2024.
With an excavated diameter of 12.3m, the tunnel for baggage is the biggest bored tunnel in Singapore at the time of construction, said Dr Wen.
The main challenge was to make sure that the disturbance to the surface was minimal, to ensure that airport operations would not be affected, especially when tunnelling under a live taxiway, he added.
With the major tunnelling works for the 1.7km stretch completed, all that is left for the tunnel project are additional construction works to connect the tunnels at both ends to the two terminal buildings.
At T2, a basement is being excavated for the construction of a baggage handling system, as well as a station and depot for the trains that will travel through the tunnels between T2 and T5, said Dr Wen.
T5, which broke ground in May, is scheduled for completion in the mid-2030s, enabling Changi Airport to serve about 50 million more passengers annually. It will house a dedicated ground transportation centre – integrating train, bus, taxi and other transport services in one location.
A worker seen next to a pair of automated people mover tunnels, which will be used to link passengers between terminals, below the ground at Changi Airport's Terminal 5 construction site, Dec 30, 2025. (Photo: CNA/Wallace Woon)
A view of the opening of an automated people mover tunnel, which will be used to link passengers between terminals, 28 metres below the ground at Changi Airport's Terminal 5 construction site, Dec 30, 2025. (Photo: CNA/Wallace Woon)
An automated people mover tunnel, which will be used to link passengers between terminals, below the ground at Changi Airport's Terminal 5 construction site, Dec 30, 2025. (Photo: CNA/Wallace Woon)
Workers walking through an automated people mover tunnel, which will be used to link passengers between terminals, at Changi Airport's Terminal 5 construction site, Dec 30, 2025. (Photo: CNA/Wallace Woon)
Lowering of the tunnel boring machine parts into the launch shaft for assembly. (Photo: Changi Airport Group)
PASSENGER TRANSPORT
Changi Airport Group had previously announced that there would be a separate people mover service between T5 and T2 via a 2.5km underground link between the terminals, which began construction in 2024.
A fleet of five trains will carry passengers between T2 and T5, with two operating at each time. Each train can carry up to 96 passengers and their bags, and a one-way journey will take about four minutes.
As for the baggage handling tunnel, Dr Wen said it will be able handle up to 3,000 bags per hour.
For now, a conveyor belt has been installed in the baggage handling tunnel to transport excavated soil from the ongoing construction at T2 to T5 for easier disposal, since T2 is an operating airport environment, said Dr Wen.
Typically, excavated earth has to be transported away using trucks, which could lead to congestion at the airport. The conveyor belt system has eliminated this issue, he added.
T5, built on a plot of land about 20 per cent bigger than Toa Payoh, will have three different parts also connected by a separate line of people movers, while its location could pave the way for air-sea transfers via Tanah Merah Ferry Terminal.
When the first phase of the T5 project is completed in the mid-2030s, it will be able to handle about 50 million passengers annually. Changi Airport’s existing four terminals now have a 90 million passenger capacity.
A new MRT station at T5 will serve as an interchange station connecting the airport to the Thomson-East Coast Line and Cross Island Line. At T5, two more tunnels that will connect to the future MRT station are being built, said Dr Wen.
The new station will be part of the Thomson-East Coast Line extension, which will provide a direct rail link between Changi Airport and the city centre, to areas such as Gardens by the Bay, Maxwell and Orchard.
Changi Airport will be connected to neighbourhoods such as Ang Mo Kio, Hougang, Punggol and Clementi via the Cross Island Line.
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