Some 1.7km of the three underground terminals linking Terminal 5 to Terminal 2 were completed in October 2024. - ST
SINGAPORE: Passengers at the future Changi Airport Terminal 5 can expect to reach Terminal 2 in four minutes via the airport’s new underground link.
The automated people-mover system – similar to the existing Skytrain, which serves Terminals 1, 2 and 3 – will operate at a frequency of four to eight minutes, said Changi Airport Group (CAG) during a media visit on Dec 30 to the tunnels linking the future mega terminal and the existing T2.
Comprising two carriages, each train will be able to hold up to about 96 passengers, or 48 per carriage, with luggage.
Two trains – out of the airport operator’s future fleet of five – will be operational at any given time during operating hours, which CAG has not decided on.
The people mover linking T5 and T2 will help transit passengers and others get to the rest of Changi Airport via the Skytrain or shuttle buses. T2 is connected to Terminal 4, which is not served by the Skytrain, via shuttle buses.
CAG previously said that transit passengers at T5 can connect to another flight in less than an hour.
In comparison, the existing Skytrain – available to both travellers and members of the public – has one to three carriages, which carry up to 50 passengers each, and arrives every one to four minutes between 5am and 2am daily.
With T5 being as big as Terminals 1 to 4 combined, it will allow Changi Airport to serve 140 million passengers yearly – over 55 per cent more than its present capacity of 90 million – once it opens in the mid-2030s.
Some 1.7km of the three underground tunnels between T5 and T2 – spanning a total of 2.5km – were completed in October 2024. Two of the tunnels are for the people mover, while the third tunnel is for baggage.
The remaining stretches of tunnel at the ends near T5 and T2 – where an interchange for the baggage-handling system, as well as the depot and station for the people mover, will be situated – are still under construction.
The baggage tunnel can facilitate the transfer of up to 3,000 bags an hour between T5 and T2.
By contrast, the baggage system connecting Terminals 1, 2 and 3 can handle more than 2,700 bags an hour, according to the Changi Airport website.
The baggage tunnel between T5 and T2 was Singapore’s largest tunnel dug using giant drilling machines – known as tunnel-boring machines – when it was being constructed in 2022, with a diameter of 12.3m.
It has since been overtaken by a tunnel stretch between Bright Hill and Turf City for the upcoming Cross-Island Line (CRL), which measures 12.8m wide. Also on the CRL, the tunnel between the future Tampines North and Defu stations has a diameter of 12.6m.
The tunnels between T5 and T2 extend 28m to 35m below ground – the equivalent of roughly a 12-storey Housing Board block.
On the challenges encountered during the construction of the tunnels, Dr Wen Dazhi, CAG’s senior vice-president for Changi East construction, told reporters that all three tunnels had to be built under an operating taxiway near T2. Taxiways allow aircraft to move to and from the runways or other parts of the airport.
Passengers at the future Changi Airport Terminal 5 can expect to reach Terminal 2 in four minutes via the airport’s new underground link.
He added that engineers had to be “very careful” in planning the operation of the tunnelling machines to ensure that the ground on the surface did not sink, so that airport operations would not be affected.
To ensure minimal disruption to Changi Airport’s operations, Dr Wen’s team is using a top-down construction method for ongoing tunnelling works near T2, which involved first setting out a concrete layer for the roof of the tunnels that allowed the ground surface to be reinstated quickly.
This meant all subsequent excavation and construction works could take place even after the airport resumed operations on the taxiway near T2, saving the team at least one or two years of time compared with traditional excavation methods, he added.
One unique solution the team devised to minimise disruption to airport operations was the use of a conveyor-belt system to transport excavated soil vertically upwards from the completed baggage tunnel to the surface for disposal.
The alternative was to use tipping trucks that ply up and down the airport apron, where aircraft operate and where passengers board.
As a result, using the conveyor belt lowers traffic volumes, reducing the risk of congestion at the airport.
This system can move up to 350 tonnes of soil per hour, similar to the amount that almost 30 trucks can carry in the same period, noted Dr Wen.
Construction on T5 officially started in May after Prime Minister Lawrence Wong broke ground on the mega terminal.
Besides building the remaining stretches of tunnel, ongoing construction work for T5 includes the foundation of the main passenger terminal and ground transport centre, which will bring together the CRL and Thomson-East Coast MRT lines, buses, taxis and other transport services.
Airside infrastructure – including aircraft stands, connecting taxilanes that allow aircraft to move from taxiways to their parking positions, and ancillary support buildings at the Changi East Industrial Zone – is also being built.
Also under construction are tunnels within T5, such as those for two other automated people-mover systems inside the terminal.
The two people-mover systems within T5 will connect departing passengers to their gates and arriving passengers to two arrival immigration halls. - The Straits Times/ANN
