RAMESWARAM: After more than two years of wait, train services are set to resume on Pamban - Rameswaram section, with a new vertical lift bridge at Pamban replacing the iconic but old structure that had long connected Rameswaram Island to the Indian mainland.
Spanning the Palk Strait in the Bay of Bengal, this new 2.08 km bridge is not only a critical transportation link but also considered an engineering feat of sorts.
Its unique feature lies in the 72.5-metre-long navigational span, which weighs a staggering 660 metric tonnes (MT). Using a theoretically simple technology — a counterweight system — to suspend 620 of the 660 MT above the sea, the bridge reduces its reliance on powerful electric motors which are now used to elevate only the remaining 40 MT.
The bridge has been cleared by the Commissioner of Railway Safety (CRS) after addressing concerns. In response to CRS observations regarding procedural lapses such as delays in obtaining approvals and measures to prevent corrosion, the Ministry of Railways issued a detailed explanation and made corrections, clearing the way for the resumption of train services to Rameswaram.
The new Pamban bridge comprises 99 spans, each 18.3 metres long, with the pivotal navigational span being the longest and heaviest component. At 660 MT, it forms a significant portion of the bridge’s total weight of 1,880 MT. The span itself is raised and lowered using an electric motor with a capacity of 760 RPM, allowing it to lift in just 5 minutes and 3 seconds, a remarkable feat when compared to the old bridge’s manual bascule mechanism which took 30 to 45 minutes.
An official from the Southern railway explained that 310 MT of steel ingots serve as counterweights on either side of the bridge, with high-tension cables connecting them to the span.
“The remaining 40 MT comprises railway tracks and other structural components. This system allows the span to be raised using an electric motor of 760 RPM capacity, lifting it within just 5 minutes and 3 seconds, compared to the 30-45 minutes required by the manually operated double-leaf bascule section of the old bridge,” said an official.
“It’s nearly impossible to lift the entire 660 MT weight using electrical power motors. The counterweight system has reduced the weight to be lifted to 40 MT,” said an engineer.
The navigational span elevates to a height of 17 metres, ensuring smooth maritime traffic. “A backup motor has been installed to ensure uninterrupted operation. Currently, the span is raised 7-8 times a month, a number expected to increase with growing vessel traffic in the Palk Strait. The high-tension cables anchoring the span are designed to last 10 years, while the navigational span itself has a life expectancy of 35 years, with the bridge projected to last 100 years,” added the official.
In terms of clearance, the new bridge offers 22 metres of airspace above sea level, three metres more than its predecessor, reducing the risk of collision between ships and the bridge. For over a century, the old bridge, which was constructed in 1914, served as the sole rail connection between Rameswaram and the mainland.
However, following severe corrosion, train services were suspended in December 2022, and since then, trains have been terminating at Mandapam.
R Srinivasan, senior deputy general manager of Rail Vikas Nigam Limited (RVNL), said, “The RDSO guidelines weren’t adequate for such a unique lift bridge. Therefore, we adopted international safety standards, which were reviewed by expert committees from IIT-Bombay and IIT-Madras.”
These international standards ensured that the design and construction surpassed the benchmark set by the railway design and standards organisation.
The foundation of the bridge consists of 333 piles and 101 pile caps, extending up to 37 metres below the seabed, designed to support two tracks.
“The welded boxes for the superstructure were manufactured in Ramanathapuram. Their quality was verified through phased array ultrasonic testing by the Welding Research Institute at BHEL (Tiruchy). These welded boxes were transported to Mandapam by road. Shifting them to the sea using a launching girder was carried out amid numerous challenges due to varying climatic conditions and opposition from locals,” explained an official.
The new bridge also reduces the labour intensity associated with its predecessor, which required 30 to 40 personnel to operate its manual double-leaf span.
A new icon
72.5 metre navigational span weighs 660 metric tonnes
Counterweight system technology reduces reliance on electric motors which are now used to elevate only 40 MT
Bridge has been cleared by Commissioner of Railway Safety after addressing concerns