In a significant engineering feat for Singapore’s aviation infrastructure, the main tunnel works connecting the future Terminal 5 (T5) at Changi Airport to the existing Terminal 2 (T2) have been completed, marking a key milestone in the Changi East development programme. 

This milestone represents the successful excavation of the primary underground link that will facilitate seamless passenger and baggage transfers between the new mega-terminal and Changi’s established terminals. When fully operational in the mid-2030s, the tunnels will form part of an integrated transit network, enabling rapid connectivity across the entire airport campus. 

Tunnel Scope and Design

The tunnelling works encompass three bored tunnels stretching approximately 1.7 km beneath one of Changi’s runways: two dedicated to passenger movement via an automated people-mover system and one for baggage transfer logistics. 

Passenger Tunnels: Designed to house future automated people movers comparable to the current Skytrain system, these tunnels will enable travellers to move quickly and efficiently between T5 and T2. Once the system is operational, journeys between the terminals are expected to take around four minutes. 

Baggage Tunnel: With an excavated diameter of 12.3 m, the baggage tunnel was the largest bored tunnel in Singapore at the time of construction, capable of handling up to 3,000 bags per hour. 

Boring works initially commenced in January 2022 and were completed later that year, with the tunnel structures certified as finished in October 2024. 

Engineering Challenges & Solutions

A key challenge for the project was tunnelling under live airport infrastructure—especially active taxiways—without disrupting ongoing airport operations. The engineering team utilized precision tunnelling techniques and sequencing to ensure ground stability and operational safety throughout the process. 

Next Steps

With the major tunnel excavation now complete, remaining works will focus on connecting the bored tunnel sections to the terminal buildings themselves. This includes integrating:

• Passenger stations and depots for the automated people mover at both T2 and T5,
• Baggage handling interchange facilities,
• Internal terminal connections for onward transit and transfers. 

Meanwhile, construction of T5 itself is progressing. The new terminal—one of the largest single-terminal projects in the world—is being developed to significantly expand Changi Airport’s capacity, with operations slated to begin in the mid-2030s. It will also feature an integrated ground transportation centre connecting rail, bus, taxi, and other transport services. 

Strategic Impact

Once complete, this underground network will allow Changi Airport to operate as a fully unified and highly efficient air hub, vastly improving passenger experience and operational flexibility across terminals. The underground link is central to Changi’s vision of delivering world-class connectivity and maintaining its position among the globe’s top aviation gateways. For further information use the tunnelbuilder archive click here 01/26.