By IANS,
New Delhi : The aircraft-style vacuum toilets Railways Minister Mamata Banerjee plans to introduce on trains on a trial basis are not only more hygienic, they will also save the rails below.
Indian engineers face a unique problem – corrosion of rails by acidic human waste. That means rails in India are more brittle and unsafe, and are required to be replaced more frequently.
Presenting the 2009-10 rail budget in parliament Friday, Banerjee said: “Field trials are being conducted for introduction of environment friendly green toilets. We are also planning to conduct trials on vacuum toilets similar to those used in aircraft in a few coaches.”
Rail corrosion due to the toilet discharge has become such a serious problem that recently scientists at the Indian Institute of Technology Kanpur (IIT-K) even developed a special alloy steel that is relatively more corrosion proof.
The stuff leaving the toilets of speeding trains in the form of fine spray corrodes the rails, R. Balasubramaniam, professor of materials science at IIT-K, told IANS in May. “It is a unique problem faced in India where long distance trains are quite common. Longer travel times invariably result in greater use of toilets and, in turn, more corrosion.”
“Rail corrosion is a major problem, especially along the salt-laden sea coasts,” H.S. Pannu, director-general of the railways’ Lucknow-based Research Designs and Standards Organisation (RDSO), had admitted.
Environmental corrosion combined with “toilet corrosion” shortens the life of rails and according to the railways, nearly Rs.4.4 billion ($89 million) is spent annually on replacement of rails withdrawn prematurely due to corrosion.
Balasubramaniam led a team that worked in collaboration with RDSO and the Steel Authority of India (SAIL) to develop the new alloy.
The rails currently in use are high carbon steels containing about 0.7 to 0.8 percent carbon and 1.0 percent manganese. “The presence of high amount of iron carbide also called ‘cementite’ renders these rails susceptible to corrosion,” he explained.
While atmospheric corrosion of rails may not endanger safety, “crevice corrosion”, taking place under the liners of the rail fastening system – and hence not visible from outside – is particularly worrisome, Balasubramaniam told IANS. “Crevice corrosion is accelerated in the presence of chloride ions near sea coasts as well as in discharge from the toilets of passenger trains.”
The railways’ own efforts to combat crevice corrosion by trying out different types of coatings in field trials failed to work.
But now trying out new chemical experiments to save the rails may not be necessary in the second largest railroad in the world under a single management, running more than 11,000 trains every day, 7,000 of them for passengers.
The network comprises 108,706 km, and vacuum and green toilets, when operationalised on trains, would save this length of rails from corrosive human waste. After all, Indian railways ferries 14 million passengers daily from 6,853 stations across the length and breadth of the country.