Bridge work: engineers use ‘controlled blasting’

Special Correspondent
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Dismantling of damaged pier proves to be Herculean task

The dismantling of the damaged pier of the century-old Pamban rail bridge turned out to be a Herculean task for the railway engineers as they had to employ an unconventional method.

After three days of concerted effort, the engineers, assisted by local contract workers, dismantled the damaged pier through “controlled blasting” using gelatin sticks. “It was very difficult to dismantle the pier, which got twisted to a 47-degree angle after the barge crashed into it. After having tried all conventional methods, we were forced to go for “controlled blasting,” a senior railway official told The Hindu .

A private agency from Sivakasi, which had expertise in rock blasting, was approached. But when the agency sought five days execution time, the engineers decided to get the job done themselves.

Though the process of dismantling the pier began on Wednesday , after completing the erection of two temporary piers on either side of the damaged pier, using steel cribs, the engineers could not make much headway as the pier was very strong.

Initially, the engineers used electric power to put drills in the pier to dismantle it. As it proved to be ineffective, they brought the railway compressor from Tuticorin and used it for drilling, which also turned out to be ineffective and time-consuming, he said.

They heaved a sigh of relief only when the pier gave way around 7 p.m. on Friday. As the base remained intact, they erected the third pier, using steel cribs in no time, setting the stage for trial run on Saturday.

Stuck tug boat

However, the tug boat, which remained stuck between rocks near the Pamban rail bridge after the barge it was towing crashed into the bridge on Sunday, would be pulled out only on January 27.

Sources in Shifa Marine, the Tuticorin-based company, which was entrusted with the salvage operation, said that on January 27, a day after full moon day, there would be maximum high tide in the seas. “It is futile to launch the salvage operation immediately as the vessel is grounded in the rocky area where the water level is only 1.5 metre deep. The water level should be at least 2.5 metre deep for the ‘V’- shaped tug boat to float,” the sources said. After the full moon, the water level is expected to raise by 0.8 meters, they added.

As the tug boat was firmly got stuck, it would not move towards the bridge. “Our divers surveyed all over the tug boat and found that the draft is very low towards the bridge. However, as a precautionary measure, we have placed three anchors to prevent it from moving towards the bridge, the sources said.

As the Divisional Railway Manager had insisted additional safeguards, the company would place two more anchors on Sunday morning, the sources added.

The sources said Shifa Marine would press into service four steel-body boats, each with 500 HP in the salvage operation. The boats would arrive Pamban on January 26.

The barge had drifted and hit the bridge as it had a flat bottom and could float even on one feet high water level, unlike the tug boat, the sources clarified.




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