Chennai Metro achieves Engineering Feat at Vadapalani with 3-Level Metro Viaduct on Corridor 4

Chennai, India (Metro Rail Today): In a landmark achievement for urban infrastructure, the Chennai Metro Rail Limited (CMRL) has successfully executed one of the most complex engineering works in its Phase-II Corridor-4 development at Vadapalani, overcoming significant space and operational constraints in the city’s busy Arcot Road area.

At the heart of this milestone is the construction of a third-level metro viaduct that passes over an existing flyover and an elevated operational metro line—a rare tri-level configuration in Indian metro engineering.

Why Vadapalani Was a Challenge

The Corridor-4 viaduct intersects the operational Corridor-2 (Phase-I) near Vadapalani Station, a zone already densely populated with infrastructure. This intersection required a 45-meter obligatory span to cross the existing metro alignment—a span too wide for conventional crane erection methods due to:

• Severe space limitations

• Ongoing traffic

• Live operational metro services

To address this, CMRL adopted the Launching Girder methodology, a sophisticated engineering technique allowing safe erection of U-girders without disturbing the underlying metro and road traffic.

The Engineering Marvel: Giant Pier Cap

A custom-designed extended pier cap was constructed to support this critical span. The dimensions are staggering:

• Length: 23 meters

• Width: 10.46 meters

• Depth: 3.5 meters

• Concrete volume: 470 cubic meters

• Weight: Approximately 1,200 metric tonnes

Remarkably, this mega-structure was completed in just two months, following successful utility shifting, thanks to meticulous coordination between civil, electrical, and traffic departments.

Mrs. Mamta Shah, MD & CEO of Urban Infra Group, commended the achievement, “This tri-level viaduct construction at Vadapalani is a shining example of what Indian metro engineering can achieve under challenging urban constraints. It reflects world-class planning and precise execution.”

Vadapalani Metro Station: A Three-Level Transit Hub

With the elevated Corridor-4 now positioned above the existing elevated line, the new Vadapalani Station is designed as a three-level structure:

1. Commercial Level – Retail and service areas

2. Concourse Level – Ticketing and commuter movement

3. Platform Level – Passenger boarding at the highest level

This vertical stacking not only saves valuable horizontal space in the densely built Arcot Road corridor, but also enhances passenger flow efficiency and multi-line connectivity at a strategic junction.

Strategic Importance of Corridor 4

Corridor-4, part of the ambitious Chennai Metro Phase-II, connects Light House to Poonamallee, spanning approximately 26 km. It plays a vital role in:

• Decongesting arterial roads

• Linking western suburbs with key employment and commercial zones

• Integrating with Corridors 3 and 5 for seamless interchanges

The Vadapalani tri-level segment is one of the most technically complex areas along the route and now stands as a benchmark for future elevated metro projects in congested urban environments.

The successful execution of the tri-level viaduct and massive pier cap at Vadapalani highlights CMRL’s engineering prowess and ability to innovate under pressure. It not only reinforces Chennai’s status as a leader in metro rail infrastructure but also offers a replicable model for urban transit in high-density zones across India. As Corridor-4 continues to progress, the Vadapalani feat will be remembered as one of its most iconic milestones.