Steps were being taken by the Railways to seek the coveted status for the bridge, built by a German engineer Scherzer, in 1913, officials said.
Once it was ascertained that the bridge met all requirements for being delared as a heritage site, a formal application would be made, Railway Board Chairman J P Batra, who along with other top railway officials witnessd the trial run after Broad Gauge conversion of the track recently, said.
"It could become the third railway site after Nilgiris Mountain Railway (NMR) and Darjeeling Himalayan Railway (DHR) in the country to join UNESCO's Heritage site. It will be the first of its kind railway bridge in the world to join the list of heritage sites," Southern Railway Chief Engineer A K Sinha, who had made a detailed study of the bridge.
The 2.06 km long bridge was considered an engineering marvel when it was constructed at a cost of just Rs 20 lakh by 600 workers. There were no loss of lives during construction.
The straight bridge from East to West has its foundation on sandstone reef. The water depth in between ranges from two feet to 10 feet. Stones used for the bridge were brought from a quarry 270 km away and sand from a site 100 km away.
Nearly 5,000 tonnes of cement, 18,000 cubic feet of crushed metal stone, 2,600 tonnes of steel and 80,000 cubic feet of boulders were used to construct the bridge, work on which began in June 1911 and was completed in June 1913. It was commissioned on Feb 24, 1914.
The Pamban rail bridge has 145 fixed spans and one navigation span which is open for ships. The drawbridge at the centre comprises two 'leaves' or sections of the navigation span, weighing 415 tonnes each.
It requires six persons on each side to manually operate and lift them for ships to pass. The total length of the span is 225 feet, probably the longest in the world.
According to Sinha, corrosion proved to be a big problem much before the cyclone. The life of girders originally put up in 1914 was short. They were changed to the BG deck type. Now steel girders had been put up. "They have been duly metalled to enhance life," he said.
Before the cyclone, the rail line actually continued till Dhanushkodi, the southern most tip of the island. The railway terminus was at Talaimannar In Sri Lanka. The cyclone washed away the rail track at Dhanushkodi.
"For the first time after Gauge conversion a ship was allowed to pass under it on June 21," Sinha said.
He said experts from IIT, Madras were now working on a design to motorise the spans so they need not be manually operated. The Navigation span attracts a lot of attention. But only a lucky few will be able to catch a glimpse of the navigation span opening up to allow passing ships," he added.