The Bhopal Metro project has entered its most challenging and sophisticated phase as preparations for the underground section reach completion. To navigate beneath the city’s dense population and historic landmarks without surface disruption, two massive Earth Pressure Balance (EPB) Tunnel Boring Machines (TBMs) are set to commence operations from a specialised deep shaft near Puttha Mill in the first week of April. Manufactured by the Robbins Company in Bengaluru, the two TBMs, each costing approximately Rs 100 crore, have arrived in the State capital. These engineering marvels are designed to excavate tunnels with a diameter of 5.8 meters. Currently, the assembly of various components is underway and is expected to be completed by late March, after which the machines will be lowered into the 20-meter deep launching shaft. The Metro Corporation has awarded a contract worth Rs 769 crore for this crucial segment of the Orange Line. The project involves constructing twin tunnels over a 3.39-kilometre underground stretch connecting Pul Patra to Bada Bagh and Sindhi Colony, with a strict completion deadline of 42 months.

 

How the EPB Technology Works:

The TBM operates as a mobile subterranean command center. It features a high-powered ‘Cutter Head’ that grinds through soil and rock at significant depths. Inside the machine, a control cabin allows operators to monitor the entire process in real-time. As the machine excavates, a ‘Segment Erector’ simultaneously installs pre-cast concrete rings to form the tunnel walls, providing immediate structural integrity. The excavated debris is efficiently transported to the surface via a ‘Screw Conveyor’ and ‘Slurry Pipes’ without halting the drilling process. The underground construction has been divided into six strategic segments. According to the Metro Corporation’s blueprint, the machines will first be deployed from the southern side of Bhopal Junction towards Pul Patra. Subsequent phases will see the project moving northwards, culminating at the Sindhi Colony station. Following Subhash Nagar, Pul Bogda will serve as a major interchange station, leading to underground stops at Aishbagh, Sindhi Colony, DIG Bungalow, and Krishi Mandi. Zero-Vibration Engineering: Addressing safety concerns, officials stated that the tunnelling will be virtually imperceptible to the residents living above. The advanced EPB technology ensures minimal surface vibration, safeguarding the city’s ancient heritage structures and densely packed residential blocks.