Mumbra–Airoli Road Tunnel: A Masterclass in Urban Tunneling

Project Overview

The Mumbra–Airoli Road Tunnel stands as a landmark infrastructure project executed within one of the most densely populated corridors of the Mumbai Metropolitan Region. This project required excavating a high-capacity roadway beneath a bustling urban landscape, where the surface was occupied by critical institutions and residential hubs.

The Challenge: The Sensitivity of Urban Alignment

The tunnel alignment was uniquely complex, passing directly beneath sensitive surface structures, including:

• Healthcare & Education: Hospitals, schools, and colleges where noise and vibration thresholds were extremely low.
• Industrial & Residential: Active factories and multi-story residential buildings requiring 100% structural integrity.
• Geological Vulnerability: Presence of shear zones and unstable rock patches that demanded immediate stabilization.

Our Technical Approach

1. Precision Controlled Blasting (PCB)

To mitigate the risks associated with urban excavation, Rocktech employed Controlled Blasting Techniques. By meticulously calculating charge weights and using electronic delay detonators, we successfully limited blast-induced vibrations to levels well below the safety thresholds of surrounding buildings.

• Real-time Monitoring: Seismographs were deployed at surface level to monitor Peak Particle Velocity (PPV) for every single blast.

2. Advanced Support Systems

To ensure the long-term stability of the tunnel and the safety of the population above, a multi-tiered support strategy was implemented:

• Systematic Rock Bolting: Providing internal reinforcement to the rock mass.
• Fiber-Reinforced Shotcrete: Immediate application of high-strength concrete to prevent air-slaking and minor rockfalls.
• Shear Zone Management: Specialized permanent support systems were engineered to reinforce weak geological zones, particularly at the critical tunnel portals.

Key Highlights & Results

• Zero Damage Excellence: Successfully completed the excavation with zero structural damage to surface features.
• Vibration Control: Maintained vibrations within strict regulatory limits, ensuring no disruption to hospital equipment or industrial operations.
• Safety First: Demonstrated that high-impact tunneling can be safely integrated into high-density urban environments through engineered solutions.

Project Quick Facts (For Sidebar/Infographic)

• Location: Mumbai (Mumbra–Airoli Link)
• Key Technology: Controlled Blasting & Seismographic Monitoring
• Surface Sensitivity: Extreme (Urban Healthcare & Residential Zones)
• Stabilization: Rock Bolts, Shotcrete, and Steel Ribs
• Geology: Varied (Basalt with Shear Zones)