Construction of a key structure for the Mumbai–Ahmedabad bullet train project has reached an important milestone with the completion of a 100-metre-long steel bridge over an underground metro tunnel in Ahmedabad district. This bridge is the 13th steel bridge completed in Gujarat for the high-speed rail corridor, out of a total of 17 such bridges planned in the state, according to an official release.
The bullet train viaduct in Ahmedabad district is largely being constructed using span-by-span (SBS) structures, with typical spans ranging between 30 and 50 metres. However, at this specific location, the alignment crosses an underground metro tunnel connecting the Kalupur and Shahpur metro stations, requiring a significant design modification.
As per the release, the foundations of the bullet train structure were deliberately placed at a safe distance from the metro tunnel to ensure that no load from the high-speed rail corridor is transferred onto the underground infrastructure. This engineering constraint necessitated increasing the span length to nearly 100 metres. Consequently, the design was altered from a conventional SBS viaduct to a steel truss bridge, ensuring structural integrity for both the bullet train alignment and the metro tunnel below.
The bridge was assembled on site at a height of 16.5 metres above ground level using temporary trestles. Once assembly was completed, the temporary supports were carefully dismantled, and the structure was lowered and positioned accurately onto permanent bearings to meet stringent safety and precision requirements.
Weighing approximately 1,098 metric tonnes, the steel bridge runs parallel to the Ahmedabad Sabarmati main line of Western Railways. The structure measures 14 metres in height and 15.5 metres in width. Fabrication was carried out at a workshop in Wardha, Maharashtra, after which the components were transported to the site using trailers.
To enable smooth assembly, a temporary platform measuring 11.5 metres by 100 metres was constructed at the site. The bridge incorporates around 45,186 Tor-Shear Type High Strength bolts, protected with a C5 system coating, and is fitted with elastomeric bearings to enhance durability and long-term performance.
