Inside Dubai Metro Blue Line: How tunnels are taking shape beneath the emirate

As Dubai moves ahead with its Metro Blue Line project, a massive machine has begun carving its way underground, cutting through layers of soil as engineers monitor its progress from above. At a site visited by Khaleej Times, tunnel walls are taking shape.

The development comes after Sheikh Mohammed bin Rashid Al Maktoum, Vice President and Prime Minister of the UAE and Ruler of Dubai, announced the launch of works on the Dubai Metro Blue Line, a 30-kilometre project with 14 stations. The line is expected to serve around one million people and reduce traffic congestion across key areas of the city.

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According to Sheikh Mohammed's announcement, more than 10,000 engineers and workers are involved in the project, which is being developed at a cost of Dh20 billion. An additional Dh34 billion has been allocated to complete the broader network, with the Blue Line scheduled for completion by September 9, 2029.

The tunnel boring machines (TBMs) are being deployed, with three machines set to move in different directions towards areas including Silicon Oasis, Rashidiya, and Ras Al Khor.

The tunnels are being dug at a depth of around 24 metres below the surface, depending on ground conditions. The tunnels are built simultaneously while excavation works are being done. As the machine moves forward, precast concrete rings are assembled inside the tunnel, forming its walls. The system operates without any human entry inside the tunnel during active drilling, with the machines controlled remotely through monitoring systems.

These concrete rings are produced at a dedicated on-site facility. Concrete is mixed, moulded and left to harden before undergoing a steam curing process. Each ring takes about 24 hours to complete, with around 24 rings produced daily. About 1,500 rings have already been manufactured, enough to keep tunnelling work going for up to three months without interruption.

The machines are capable of advancing between 13 and 17 metres a day, depending on ground conditions. As they move forward, tunnel segments are installed continuously, allowing the structure to take shape underground in real time.

At one of the key stations under construction in International City, multiple directions will converge, making it one of the largest interchange points on the line.