Spit eats into base of Howrah bridge in Calcutta

Spitting is threatening the safety of Howrah bridge with the daily onslaught of gutkha spat out by pedestrians corroding the protective hoods at the base of its pillars. Officials of Calcutta Port Trust, the custodian of the 67-year-old bridge that bears the weight of over 100,000 vehicles every day, said the commuters’ collective spit power had reduced the thickness of the steel hoods protecting the pillars from six to three millimetres since 2007.

“Gutkha contains highly corrosive elements that erode even steel. A safety audit is now being planned to find out the effect of constant spitting and several other factors on the stability of the hangers that transfer the load of traffic uniformly across the structure,” a senior port trust official said.



Forensic sciences expert Biswanath Kahali confirmed that accumulation of gutkha-laced spit on steel would have the same effect that acid has. “Slaked lime combined with catechu and tannin, which are all components of gutkha, form an organic compound that acts as a corrosive agent on a steel surface. In combination, these substances can gradually corrode a steel structure,” added Kahali.

A port trust official said the base of all 78 hangers had suffered extensive damage over the years with pedestrians passing by treating the bridge as a spittoon. “These hangers help transfer the load of the bridge from the deck to the girders. So any damage to the hangers constitutes a threat to the safety of the bridge.”


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The port trust had replaced all the hanger-base covers in 2007 after they were found to have been damaged. “We spent several hundred thousand rupees on replacing these but 50 per cent of the hoods have been eroded within three years. The 6mm bases are now around 3mm each. If corrosion continues at such a rate, we would need to decommission the bridge for repairs,” warned a port trust official.

An estimated 500,000 pedestrians use the bridge every day to cross the river. The most damaged parts of the bases are along the pedestrian walkways of the landmark bridge. “Those on the side of the thoroughfare are not damaged. This proves that pedestrians chewing gutkha and spitting are the culprits,” said an official. Officers of North Port police station claimed they were routinely imposing fines on pedestrians caught spitting. “However, it is not possible to deploy personnel to prevent spitting on the pillars given our manpower shortage,” said an officer at the police station.