Chennai Metro Rail Limited (CMRL) has successfully completed a key construction challenge at Vadapalani for Corridor-4 (Poonamallee to Light House) of the Phase-I Corridor-2 line.

At Vadapalani, the new Corridor-4 alignment crosses over the existing Phase-I Corridor-2, where the site already accommodates a busy flyover and an elevated metro line. To integrate the new line, engineers built the viaduct at a third level, ensuring clearance for the overhead traction system without affecting ongoing traffic or metro services.

A major engineering hurdle was the 45-metre obligatory span on the Phase-I corridor at the junction. Traditional crane erection methods were not feasible due to heavy traffic and the active metro line below. Instead, the CMRL team adopted a launching girder method to position the U-girders safely across the stretch.

An extended pier cap was specially designed to support the structure, measuring 23 metres in length, 10.46 metres in width and 3.5 metres in depth. It required 470 cubic metres of concrete and weighed about 1,200 metric tonnes. Construction of the pier cap was completed within two months after utility shifting.