ROB at Aurangabad-Sone Nagar section of NH2

The project involved dismantling an existing 4-Lane Rail Over Bridge (ROB) over three Indian Railway (IR) Tracks between Daltonganj - Sone Nagar at KM: 407/29-408. This bridge connected Aurangabad - Sone Nagar over National Highway-2 on the Mughal Sarai - Gaya Section.

The existing ROB's structure consisted of a pre-stressed cast-in-situ ribbed solid slab with an effective span length of 26m. The challenge was to dismantle the 1000MT superstructure across live railway tracks without causing safety issues or damaging railway property.

We devised a dismantling scheme that entailed piece-by-piece removal using 500T cranes. These cranes were positioned behind the abutments to lift and remove smaller segments cut on-site. This method, developed in close discussion with the contractor, resulted in approximately $400k in savings compared to the scheme of removing an entire rib through de-launching on a temporary platform and off-site cut.

We first cut and removed the deck slab. Then, we started removing the prestressed ribs, each weighing 200 tonnes. A temporary platform, composed of four braced plate girders, was placed in a bay between two ribs. Both cranes lifted the rib onto this temporary platform in tandem, which was then cut into four 50t pieces and removed individually by each crane. This process was repeated for the other two ribs.