Gutkha corroding Howrah Bridge,shows study

Kolkata Port Trust has said saliva laced with gutkha is corroding the iconic 70-year-old bridge.

The Howrah Bridge is under attack from gutkha-chewers. The Kolkata Port Trust,which maintains Kolkatas best known landmark,has said that saliva laced with gutkha is corroding the iconic 70-year-old bridge.

KoPT chief engineer A K Mehra said studies had found thick layers of gutkha deposits on the covers of hanger bases on either side of the bridge,and chemical tests had shown a severe reduction in the thickness of the covers. It was obvious that the corrosion had been caused by chemicals in gutkha,Mehra said.

The superstructure of the bridge is held up on a deck slab by 39 hangers on each side. The hanger bases along the pedestrian walkway have shown the worst corrosion,and port authorities reckon that constant spitting by gutkha-chewing pedestrians has resulted in the saliva seeping through.

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Some 5,00,000 pedestrians are estimated to use the bridge every day. The hanger bases are made of mild steel plates 6 mm thick. Debasish Roy,associate professor of chemical engineering at Jadavpur University,said gutkha,which contains slaked lime,catechu (khair or kattha),supari and tobacco,can corrode the metal.

The KoPT had in 2007 replaced all hanger base covers (hoods) of the bridge after the steel plates were found to have eroded considerably. It has now decided to use fibreglass covers which can be washed and are,because of the absence of much re-sale value,unattractive to thieves.

The Howrah Bridge,officially known as Rabindra Setu,was built between 1937 and 1942,and opened to traffic in February 1943.

According to a study by the transport department of the West Bengal government,in 2007,1.1 lakh to 1.5 lakh vehicles used the bridge every weekday. That number is likely to have since increased substantially.