Mumbai: The Mumbai-Ahmedabad Bullet Train project has achieved a key milestone in Vadodara with the successful launch of all 14 portal beams over the Delhi–Mumbai Rajdhani main line.
The completion of all 14 portal beams is not only a major construction milestone but also an important step in integrating the Mumbai-Ahmedabad Bullet Train corridor with Vadodara’s existing railway network while negotiating one of the busiest railway routes in the country.
The 14 portal beams have been strategically constructed along the complex Vadodara stretch, where the Bullet Train alignment crosses multiple operational railway lines. Their completion clears a major structural requirement for launching the 40-metre composite girders over the Rajdhani main line and advancing the elevated corridor through this critical section.
The Vadodara stretch, approximately 8.3 km long, passes through a densely developed railway and urban environment and crosses five Indian Railways lines that includes two main lines. The alignment also crosses diagonally over the Delhi–Mumbai Rajdhani main line, requiring specially engineered structures to maintain the required clearances and ensure safe and uninterrupted integration with the existing railway system.
To negotiate these constraints, 14 portal beams have been provided over the Delhi–Mumbai Rajdhani main line track. Of these, 10 are located between Vadodara Bullet Train station and Vishwamitri Railway station towards the Surat end, while four are located between Vadodara Railway station and Chhayapuri Railway station towards the Ahmedabad end.
The portal beams form the structural framework over which the superstructure of the Bullet Train viaduct will be constructed. Composite girders of approximately 40 metres span will subsequently be launched over the 14 portal beams at the Rajdhani main line crossing, while Span-by-Span (SBS) launching will be adopted at the remaining portal beam locations.
The portal beams have been constructed using the cast-in-situ method, necessitated by the highly constrained locations and the need to work around operational railway infrastructure. Each portal beam constructed over the railway tracks weighs approximately 1,500 tonnes on completion, making conventional precast launching impractical at these locations.
The beams, measuring approximately 4 metres in height, 4 metres in width and 37 metres in length, require around 590 cubic metres of concrete each. The reinforcement cage alone weighs approximately 55 tonnes.
The construction of these structures involves specialised high-capacity cranes, hydraulic jacks, long-boom concrete pumps and precision surveying equipment. Given that several structures are being constructed above operational railway infrastructure, the work requires detailed sequencing, continuous monitoring, close coordination with Indian Railways and controlled railway blocks wherever required.
