2021Policy
A Duty On Imported Machines
The Budget withdraws the customs exemption on TBMs: 7.5% on whole machines, 2.5% on parts imported to build TBMs here. Building here becomes the cheaper route.
Read · Budget 2021 · YourStory
An X-Ray Explainer
Inside India’s Biggest Tunnel Boring Machine
A 15.62-metre Mixshield of the type now built in Chennai. What every part does, who makes it, and how much of it is really Indian.
By Tushar Gupta · PolityPolicy · 23 October 2026
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For Real
This is the 13.6 m Mixshield on Mumbai's bullet-train tunnel: the same type as the 15.62 m machine in our model, but built at Herrenknecht’s plant in China in 2024 and held up for months over customs clearances before reaching Mumbai in March 2026.
For Real
The Job
Beneath Mumbai
Two 3.1 km road tunnels, 13–23 m under the Versova–Dahisar Link Road, through basalt as hard as 150 MPa.
How It Works
Dig, Then Build
The wheel cuts about two metres of rock, then stops. A rotating arm, the erector, lifts ten curved concrete segments into place to close a ring. The rams push off that ring, and the cycle starts again.
1 · Cut2 · Build A Ring3 · Push Off
The wheel is cutting
The Lifeline
Rock Leaves As Mud
Crushed rock is pumped out in slurry to a plant beside the shaft, cleaned, and sent back down.
The Machine
15.62 Metres Across
India’s largest TBM type, being built in Chennai in modules with core components from Schwanau, Germany. Our model is a reconstruction of this class. Now, the X-ray.
Taken Apart
28 Assemblies
The machine, pulled apart into its modules. It ships in pieces and is put back together underground. Each part gets two labels:
Made Today
Made In IndiaThe finished part is manufactured in India, even to a foreign design.
Partly IndianIndian steel or assembly around a key piece that is imported.
ImportedArrives finished from abroad.
India’s Plan
Already Made HereNothing left to localise.
Plan AnnouncedA named company has announced making it in India.
Being DesignedNamed in BEML’s 2025 design brief; no maker or date yet.
EventuallyNothing announced yet.
For Real
The Verdict
How Indian Is It?
0Made In India
0Partly Indian
0Imported
9Already Made Here1Plan Announced3Being Designed15Eventually
The steel is Indian. The heart and the brain are imported. Four assemblies are confirmed for this machine; the rest show how machines of this class are usually supplied.
Status last reviewed 23 October 2026.
The Critical Path
Six Parts India Still Has To Crack
Main bearing, main drive, frequency converters, controls, hydraulics and the separation plant on the surface: all imported, all made to order, and the longest waits if anything breaks.
Your Turn
Take It Apart Yourself
Spin it, tap any part, filter by where it comes from.