‘With lift span provision at Rameshwaram’s new Pamban bridge, even bigger vessels can pass easily’: R Srinivasan of RVNL

Q: Can you explain the significance of the new Pamban Rail Bridge and it being the country’s first vertical lift bridge?

R Srinivasan: The Pamban Bridge, located in Tamil Nadu, connects Rameswaram island with the Indian mainland. It is unique because it is the first vertical lift span bridge in India. It is the first of its kind in Asia as well. The Pamban sea bridge stretches over 2.10 km with several spans. Out of these, one navigational span/girder is 72.5 meters long, while the remaining spans are 18.3 meters each. The new bridge allows Mail and Express trains to run at 75 kmph, unlike the older bridge (currently closed) that allowed trains to run only at 10 kmph.

R Srinivasan, Senior Deputy General Manager at Rail Vikas Nigam Ltd (RVNL)

Once opened, the Pamban rail bridge will connect Rameswaram island with the mainland, including various parts of the country. In a day, 17 Mail/Express trains, including passenger trains, would travel to and from Rameswaram.

Q: What makes this bridge stand out?

Srinivasan: The most remarkable feature of this bridge is the vertical lift span, which is lifted using electromagnetic technology, instead of manual operation. The lifting process takes 5 minutes and 30 seconds to go at a height of 17 metres, and the span weighs 660 metric tonnes. The lift spans are supported by four towers, and the combined weight of the towers and counterweights is 1,450 metric tonnes. Additionally, the bridge is built with 336 piles, all made of stainless steel to prevent corrosion.

The Railway Design and Standards Organisation (RDSO) mandates that any bridge constructed within 30 km of the sea must use stainless steel reinforcement instead of ordinary steel to combat corrosion. Since the Pamban Bridge is located over the sea, stainless steel reinforcement was used throughout the bridge. Furthermore, the fabrication of bridge components was done 60 km away from the sea to maintain the quality of the materials.

The Commission of Railway Safety (CRS) granted permission to begin commercial operations in November last year, and the bridge is now awaiting official inauguration.

Q: Why was there a need for a lift bridge instead of constructing a bridge at a higher elevation to allow easier vessel movement?

Srinivasan: The need for a lift bridge arose due to certain constraints. There is already a road bridge crossing the rail bridge. So, building a new bridge on a higher elevation wasn’t possible without interfering with the existing infrastructure. Additionally, considering the coastal area’s high wind speed — averaging around 40 kmph daily – constructing a high sea bridge for Railways could be unsafe as it might topple the railway coaches. As the road overbridge is over 22 metres in height at the vessel navigational route site, the rail overbridge has to be constructed above that, which was not feasible due to wind speed.

Once opened for use, the Pamban rail bridge will connect Rameshwaram island with the mainland, including various parts of the country.

At present, due to the old bridge, which is non-functional, ships and bigger vessels need to use the water route via Sri Lanka. With the new Pamban bridge lift span provision, even bigger vessels can pass easily, provided the Tamil Nadu Maritime Department informs the Railways in advance about the vessel movement, if any.

The height difference between the new bridge and the old bridge is 3 metres. The new bridge is 6.5 metres high. But its longest navigational lift span can go up to 17 metres. In contrast to the old bridge, where the cantilevers open up having a navigational span length of 68 metres, the new bridge has a navigational span/girder that can rise to 17 metres (height) with a length of 72.5 metres. Moreover, the new bridge is equipped with safety standards, including mechanisms to ensure that the bridge can withstand wind speed of up to 58 kmph. Beyond that, the signal automatically turns red, restricting train movement until the wind speed is normal.

Q: Can you elaborate on the challenges involved during construction?

Srinivasan: Ordinary welding was not sufficient in the case of the Pamban Railway Bridge. Highly skilled welding was required for its construction. So we enlisted the Welding Research Institute, Tamil Nadu, to train and qualify the welders. Only those certified by the institute were employed for the job. Additionally, all segments of the bridge were painted with rust-resistant coatings to protect them from corrosion.

The fabrication parts of the bridge were built 60 km away from the site to maintain the quality of the segments cast. As the construction was taking place in a coastal area, high wind speed was a major challenge. The bridge construction began in February 2019. It was completed last year with the help of 400 workers on site daily. However, the work got affected during the Covid-19 outbreak.All required permission has been obtained for commercial operations to begin.