Changi's T5 Underground Link to Put Terminal 2 Four Minutes Away

A Four Minute Ride Beneath a Growing Airport

Changi Airport's future Terminal 5 will connect to Terminal 2 through an underground train journey lasting four minutes, part of a 2.5 kilometer tunnel network designed to move passengers and baggage beneath an operating airport. The connection will help tie Singapore's largest airport expansion into the existing terminal complex when T5 opens in the mid-2030s.

Three tunnels form the link: two for an automated people mover, similar to Changi's Skytrain, and one for baggage. Together, they will allow travelers and their bags to move separately between the new terminal and the airport's established facilities. The baggage connection is designed to handle up to 3,000 bags an hour.

Terminal 5 and the wider Changi East development will nearly double the airport's size. T5's first phase will provide capacity for about 50 million passenger movements annually, lifting Changi's total annual capacity from 90 million to 140 million, an increase of more than 55 percent. Capacity describes how many passengers the facilities can accommodate each year.

Dr. Wen Dazhi, Changi Airport Group's senior vice president for Changi East construction, explained the purpose of the underground connections during a media visit to the tunnels:

"The tunnels enable Changi Airport to operate as a single integrated airport," said Dr. Wen Dazhi, Changi Airport Group's Senior Vice President for Changi East construction.

For passengers, the aim is a connected airport rather than a new terminal operating apart from the others. For Singapore, the investment supports Changi's role as a global aviation hub while preserving the service standards of an airport consistently ranked among the world's best.

Three Tunnels, Up to 35 Meters Underground

The underground network runs 28 to 35 meters below ground level, a depth compared with a building of about 12 stories. By October 2024, approximately 1.7 kilometers of the planned 2.5 kilometers had been completed. That construction snapshot shows how much of the link was already in place more than a year before January 2026.

The baggage tunnel has a diameter of 12.3 meters. When construction began in 2022, it was Singapore's largest tunnel drilled using a tunnel boring machine, a machine that excavates a circular passage underground. Tunnels for the upcoming Cross Island Line have since exceeded that size.

The construction contract describes a baggage passage nine meters wide and train tunnels more than six meters wide in each direction. The passenger tunnels and the dedicated baggage route allow both transport systems to operate at the same time without sharing their passageways.

Part of the work passes beneath an active taxiway near Terminal 2. A taxiway is the route aircraft use to move between runways and terminal gates. Keeping that surface stable was essential because ground movement during excavation could affect its usability, disrupt flight schedules and create safety risks.

How the Passenger Trains Will Work

Each train on the T5 to T2 connection will have two carriages, carrying up to 96 passengers with luggage, or 48 per carriage. Two trains from a fleet of five will operate at any given time during service hours, with departures every four to eight minutes. Changi Airport Group has not finalized the service's operating hours.

The trains will be fully automated, requiring no drivers, and will travel at speeds of up to 80 kilometers per hour. The system is described as having capacity to transport approximately 10,800 passengers an hour when T5 reaches full operations in the mid-2030s. Automation is intended to improve operating efficiency and reduce potential delays.

The existing Skytrain uses trains with one to three carriages, each carrying up to 50 passengers. It runs every one to four minutes, from 5am to 2am daily. The new connection's proposed timetable is less frequent, while its fixed configuration provides two carriages for each departure.

Terminal 2 will become the interchange between the new underground service and the existing airport transport network. Passengers arriving from T5 will be able to take the Skytrain to Terminals 1 and 3. Terminal 4, which has no Skytrain service, will remain accessible by shuttle bus.

At Terminal 2, excavation of a basement will create space for the people mover's station and depot. The work is being planned around continuing terminal operations, adding the facilities needed for the expansion while limiting disruption to travelers using the airport today.

Moving Bags Alongside Connecting Passengers

The dedicated baggage tunnel will transfer up to 3,000 bags an hour between T5 and T2. The existing baggage system connecting Terminals 1, 2 and 3 handles more than 2,700 bags an hour. The new route therefore adds a larger stated hourly transfer capacity to support the airport's growth.

Changi Airport Group says transit passengers at T5 will be able to connect to another flight in less than an hour. Achieving that requires more than a short train journey: baggage also needs to reach the next aircraft efficiently. Giving bags their own tunnel allows their transfer to proceed independently of passenger transport.

The four minute ride is the journey between T5 and T2. Passengers traveling onward to another terminal will use the connecting services from T2. The underground link is intended to keep transfers practical across the expanded airport, helping Changi remain attractive to travelers choosing where to change planes.

Building Under a Working Taxiway

Dr. Wen and the construction team had to control movement at the ground surface while excavating beneath airport infrastructure. Near Terminal 2, they used a construction method that starts at the top: a concrete roof is built first, allowing the surface above it to be reinstated while excavation continues underneath.

That approach allowed construction to proceed after the taxiway near T2 resumed operations. Compared with traditional excavation methods, it saved at least one to two years of construction time while reducing the interruption to aircraft movements.

The team also developed a conveyor belt system to lift excavated soil vertically from the completed baggage tunnel to the surface for disposal. The alternative involved tipping trucks carrying soil through the airport apron, the area where aircraft operate and passengers board. Reducing truck movements helped limit congestion and safety risks in that working area.

Dr. Wen described the conveyor's capacity and the number of truck movements it could replace:

"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 Dazhi, explaining the efficiency of the conveyor-belt system.

The roof construction method and the conveyor address different parts of the same problem: how to remove large amounts of earth and build permanent infrastructure while aircraft continue using the airport above and alongside the work.

Contracts Behind the Underground Expansion

Shanghai Tunnel Engineering Company secured a S$622 million contract, equivalent to US$456 million, to build the 2.5 kilometer link between T5 and T2. Its scope covers the baggage passage and the train tunnels running in each direction.

Changi Airport Group also awarded a S$999 million contract for tunnels within Terminal 5 to a joint venture between Japan's Penta-Ocean Construction and Koh Brothers Building & Civil Engineering Contractor. The latter is a subsidiary of Koh Brothers Eco Engineering.

Those internal tunnels will carry passengers and baggage between T5's concourses, the sections containing boarding gates, and provide routes for shared utilities. Their sub-tunnels will accommodate automated people movers, baggage handling systems and a common services tunnel for electrical power, communications and water services.

The contract also includes a ventilation building and provisions for a future underground infrastructure tunnel. Reserving that space during construction allows the terminal's underground network to accommodate later infrastructure needs.

These awards follow S$4.75 billion in other T5 contracts: S$3.8 billion to a joint venture between the Singapore branch of China Communications Construction Company and Obayashi Singapore, and S$950 million to Hwa Seng Builder. Changi Airport Group has awarded more than S$5.7 billion in contracts for various parts of T5 construction, reflecting the scale of the terminal and its supporting infrastructure.

A Terminal Designed Around Three Sections

Terminal 5 will comprise T5A, T5B and T5C, located at intervals of one kilometer. T5A will contain the arrival and departure halls, immigration facilities and baggage collection. Boarding gates and other services will be spread across all three sections.

An underground automated people mover, similar to the existing Skytrain service, will carry passengers between these sections. This internal system will serve movement within T5, alongside the separate underground connection linking the new terminal to T2.

The layout will also allow T5 to operate as smaller sub-terminals when needed. That flexibility gives operators a way to manage parts of the large complex separately rather than always running the entire building as a single space.

Singapore Airlines and its budget subsidiary Scoot will make T5 their home, bringing together operations currently spread across three terminals. Consolidation is intended to improve operating efficiency and the passenger experience by placing the airlines' activities within the new terminal complex.

Changi Airport Group chief executive Yam Kum Weng described the intended balance between scale and comfort:

"Our vision is for T5 to be mega yet cosy, a terminal that embraces the Changi DNA - delivering a personalised, stress free and positively surprising airport experience," said Changi Airport Group CEO Yam Kum Weng.

Rail Connections Beyond the Airport

Terminal 5 will have a dedicated ground transportation center bringing together the Cross Island Line (CRL), the Thomson-East Coast Line (TEL), buses, taxis and other transport services. A new MRT station will serve as an interchange between the two rail lines, helping passengers reach the airport with less reliance on private vehicles.

The TEL extension will provide a direct rail connection between Changi Airport and the city center, including Gardens by the Bay, Maxwell and Orchard. It is intended to reduce travel time between the airport and Singapore's central business district for business and leisure travelers.

The CRL will connect T5 with areas including Ang Mo Kio, Hougang, Punggol and Clementi. Two additional tunnels connecting to the future MRT station are under construction as part of the terminal development.

Ong Chee Chiau, Changi Airport Group's managing director for Changi East, also highlighted the possibility of air and sea transfers because T5 will be near Tanah Merah Ferry Terminal. Its location could allow convenient ferry connections to neighboring destinations, extending the terminal's transport connections beyond roads and rail.

Solar Power, Flood Protection and Smaller Spaces

Terminal 5 is being designed to achieve Green Mark Platinum Super Low Energy Building certification. Advanced building management systems will control and optimize energy use across the facility, supporting its environmental targets.

One of Singapore's largest rooftop solar panel systems is planned for the terminal. Its expected annual electricity output is equivalent to the amount needed to power approximately 20,000 flats with four rooms built by the Housing Development Board. The installation will contribute renewable electricity and reduce the airport's carbon footprint.

The terminal will be elevated 5.5 meters above sea level to address risks from global warming and rising seas. Aircraft taxiways will be sloped to improve rainwater drainage. Together, these features are intended to help manage stormwater during high tides, extreme storms and heavy rainfall, supporting continued airport operations in adverse conditions.

T5's roof will consist of curved sections at different heights rather than one large covering over the entire structure. The design, described as "roof leaves," will divide the vast building into smaller spaces. Natural light and landscaping will help create what Changi Airport Group calls a "familiar cosy yet uplifting feel."

For passengers, those choices are intended to make a terminal handling tens of millions of travelers feel more comfortable and manageable. The design connects the practical demands of a large building with the airport's stated ambition to retain a sense of familiarity.

Automation From Baggage to Boarding Bridges

An Integrated Operations Center will bring together current operating information so airport teams can understand conditions across T5 and respond more quickly to changes or disruption. Decisions will be supported by data showing what is happening at the time.

Ground handlers will have a clearer picture of aircraft activities and possible delays, helping them allocate staff and equipment before problems affect passengers. Autonomous vehicles will shuttle passengers and staff within the terminal complex, with the aim of improving traffic flow and safety.

Automated baggage transfers and handling systems will help keep bags moving efficiently during adverse weather. Automated aerobridge docking will guide the enclosed boarding bridges into position at aircraft, improving productivity and operating efficiency while reducing the potential for human error.

These systems are intended to make the terminal more reliable as passenger volumes grow. Their shared purpose is to give operators better information, reduce repetitive manual tasks and help services continue when weather or flight schedules create pressure.

From the 2013 Announcement to the Mid-2030s

Terminal 5 has been in development for more than a decade. The project continued through land preparation and design work before the COVID-19 pandemic brought a pause. Work resumed in 2022, preserving the expansion plan while adapting to changed circumstances.

The main milestones trace the project's progress:

• 2013: Initial plans for Terminal 5 were announced.
• 2014: Land preparation began.
• 2018: Consultants were appointed.
• 2020: The project was paused because of the COVID-19 pandemic.
• 2022: The project resumed, and construction of the underground link began.
• May 2024: Terminal 5 construction officially began following a groundbreaking ceremony officiated by Prime Minister Lawrence Wong.
• October 2024: About 1.7 kilometers of the 2.5 kilometer tunnel network had been completed.
• Mid-2030s: Terminal 5 is scheduled for completion, with its first phase able to handle about 50 million passenger movements annually.

With T5 operating, Changi's annual passenger capacity will reach 140 million. That places its planned capacity above the threshold used to describe Asia's mega airports, those handling more than 100 million passengers a year. Changi's network is also projected to grow from around 170 city links to more than 200 by the mid-2030s.

The groundbreaking marked a major step in the largest expansion in Changi's history. The terminal's scale, underground connections and flexible layout are intended to support that growth while keeping transfers and daily operations manageable.

Jobs, Cargo and Singapore's Aviation Position

Prime Minister Lawrence Wong said T5 would create opportunities for Singaporean companies and workers, including jobs in data science, robotics and sustainability. Those areas connect the airport's growth with Singapore's plans to develop workers' skills and expand employment in technically demanding fields.

Construction itself is generating activity for international and local businesses. The involvement of companies such as Koh Brothers Eco Engineering in major infrastructure work reflects the development of Singapore's ability to undertake complex projects on a large scale. That experience could also be applied to projects in other markets.

Once T5 opens, the terminal will increase demand for services and workers at the airport and in supporting industries. Expanded cargo facilities in the Changi East Industrial Zone will lift handling capability to 5.4 million tonnes annually, supporting Singapore's logistics role and creating further employment opportunities in that sector.

Tourism, business travel and cargo logistics will also benefit from wider international connections. More routes and passenger capacity support Singapore's accessibility as a place to invest, conduct business and visit, while helping companies reach international markets.

At the groundbreaking, Wong said Singapore and Changi could not afford complacency and must "continue to work hard." He said Changi, like Singapore, had "defied the odds to thrive and succeed beyond all expectations." His comments framed T5 as a continuing investment in the country's aviation position amid regional competition.

The additional capacity for 50 million passenger movements each year gives Singapore room to accommodate growth in regional and international travel. The pause in 2020 and resumption in 2022 also show how the project has adjusted to disruption while retaining its long term purpose. The immediate engineering task is to connect that future capacity to the airport already operating around it.

Key Points

• T5 and T2 will be connected by a four minute underground train ride through a network totaling 2.5 kilometers.
• Two tunnels will carry passengers, while a third will transfer up to 3,000 bags an hour.
• Each passenger train will carry up to 96 people with luggage, with proposed departures every four to eight minutes.
• The tunnels run 28 to 35 meters underground, including beneath an active taxiway near T2.
• Building the tunnel roof before excavating underneath saved at least one to two years; a conveyor can remove up to 350 tonnes of soil an hour.
• T5 is scheduled for completion in the mid-2030s, adding capacity for about 50 million passenger movements annually and lifting Changi's total to 140 million.
• Singapore Airlines and Scoot will move to T5, which will also connect with the Thomson-East Coast Line and Cross Island Line.
• Plans include extensive solar power, flood protection, automated operations and cargo handling capability of 5.4 million tonnes annually in the Changi East Industrial Zone.
• Changi Airport Group has awarded more than S$5.7 billion in contracts for various T5 construction projects.