GMLR First TBM Digs In as BMC Races Second Bore

Live Tunnelling Begins Under SGNP

The Brihanmumbai Municipal Corporation (BMC) has shifted the Goregaon-Mulund Link Road (GMLR) Phase 3(B) from a clearances-led programme into live tunnelling.

The first of two tunnel boring machines—named Tulsi—began excavating under Sanjay Gandhi National Park on 17 August 2026.

The twin 5.30 km, three-lane bores run between Dadasaheb Phalke Chitranagari in Goregaon East and Amar Nagar in Mulund West.

Additional Municipal Commissioner (Projects) Abhijit Bangar’s site review, held with Chief Engineer (Bridges) Rajesh Mule, exposed the harder question behind the milestone: pace.

Roughly 9 metres of advance in the opening days indicates a TBM still moving through its learning curve. Bangar’s directive to deploy additional manpower and protect the excavation rate is a schedule-compression order, not routine oversight.

The Second TBM Sets the Commercial Timeline

The second TBM is the sharper commercial signal. Assembly stands at about 70%, with a hard deadline of 30 September 2026 and a Site Acceptance Test opening on 1 October 2026.

For executing contractor Afcons Infrastructure, the SAT gateway now defines the critical path—standby plant, crew mobilisation and machine acceptance all incur cost before any second-bore advance is banked.

The structural shift here is from approval risk to mechanical availability and advance-rate risk.

Tunnelling beneath Sanjay Gandhi National Park carries:

- Basalt variability
- Groundwater ingress
- Strict settlement and ecological monitoring obligations

The first bore’s sustained advance rate—not the ceremonial start—will determine whether the twin-bore programme holds its schedule.

Broader Market Signal

BMC remains the dominant decision-maker and funder through its capital budget, while Afcons Infrastructure carries execution and schedule exposure.

The actionable signal for contractors and suppliers is that Mumbai’s tunnelling programmes are now governed by assembly deadlines and acceptance tests as much as by geological or clearance gateways.