India's first 31-metre U-girder successfully cast for Bengaluru Suburban Rail Project

Bengaluru: The Bengaluru Suburban Railway Project (BSRP) will use 31-metre-long, single-span U-girders upon which tracks can be laid immediately.

It is the first time in India that U-girders of this length are being used to build rail-based transport systems.

On Saturday night, L&T Ltd cast the first U-girder at the casting yard in Devanahalli, marking a milestone in the 149-km project slated to be ready in 2028.

K-RIDE, the project implementing agency, said that 450 U-girders would be launched on the elevated eight-km Hebbal-Yeshwantpur section of the Mallige Line (Benniganahalli-Chikkabanavar).

M B Patil, Minister for Infrastructure Development, called it a momentous occasion.

“I have always believed that the BSRP will not only be a game-changer for Karnataka, but will also change the way we visualise commuter rail travel,” he said.

U-girders are U-shaped, pre-tensioned and precast girders used in metro projects. They ensure quality and save construction time because their extra length helps reduce the number of foundations as well as piers. Metro projects use 28-metre-long U-girders, according to K-RIDE.

A U-girder requires 69.5 cubic metres of M60-grade concrete and weighs 178 tonnes. After being cast in the yard, it is transported to the worksite and launched over piers using high-capacity cranes/launchers.

Unlike box girders, which consist of multiple, post-tensioned segments between two piers, just one U-girder is enough to build a span between two piers. A single-span U-girder can be built in a single night, as against six to seven days required to construct segments.

The segmental box girder also weighs much more than the entire span of a U-girder, K-RIDE said.