Ahmedabad: The Mumbai–Ahmedabad High-Speed Rail (MAHSR) project has achieved another major engineering milestone with the successful completion of a 100-metre-long steel bridge over an underground metro tunnel in Ahmedabad district. This structure is the 13th steel bridge completed in Gujarat out of the total 17 planned in the state, highlighting the rapid progress of the ambitious bullet train corridor.

Overcoming the “Metro Challenge”

The MAHSR project involves a predominantly elevated 508-km alignment requiring thousands of spans. As of mid-2025, over 6,455 full-span launching method (FSLM) girders of 40 metres and 925 span-by-span (SBS) girders of 30–40 metres have already been used to construct nearly 300 km of viaduct. However, this particular stretch in Ahmedabad demanded a unique solution as the bullet train alignment crosses above the underground metro tunnel connecting Kalupur and Shahpur stations.

Unlike the usual 30–50 metre spans used for the viaduct, engineers increased the span length to about 100 metres to ensure that no structural load is transferred onto the metro tunnel. This required redesigning the superstructure from an SBS viaduct to a steel truss bridge, ensuring safety for both the high-speed rail corridor and the metro infrastructure.

Technical Specifications and Assembly

Weighing 1,098 metric tonnes, the bridge stands 14 metres tall and 15.5 metres wide, and was fabricated in Wardha, Maharashtra, before being transported to Ahmedabad.

The bridge was assembled 16.5 metres above ground on temporary trestles, then carefully lowered onto permanent supports with precision. To support construction, a temporary 11.5×100 metre platform was built at the site. The structure uses around 45,186 high-strength Tor-Shear bolts, along with C5 protective coating and elastomeric bearings, enhancing durability and long-term performance. Officials say the bridge represents a distinct engineering achievement due to its complex integration with existing metro infrastructure while maintaining the integrity of the bullet train project. DeshGujarat