Corroded railway bridges
Steel structures, bridges or buildings, need protection against corrosion. Rusting of steel is a natural phenomenon. Oxygen from the ambient air while in contact of the exposed steel surface forms ferrous oxide which is called rust or corrosion that eats upon the steel surface, ultimately leading to failure of the structure.
To prevent this destructive natural process, steel surface is covered with paint covering, first a red-oxide primer and then one or two coats of weather resistant paint. But before application of the rust protecting paints, the surface must be clean and free from any trace of corrosion; else the applied coating will spill off in no time. The department responsible for erection of steel structures is also responsible for protection of those structures from corrosion with application of anti-rust paint on all the exposed surfaces as an essential part of regular maintenance.
Unfortunately, it's never done. Thus, the recent media report that 6oo bridges of the Bangladesh Railway are on the verge of collapse posing threat to the lives of the millions of passengers passing over these bridges daily is very timely. I am sure that this will draw the attention of the higher authorities. I am also sure that these bridges have never been maintained after their construction. (To verify the veracity of this statement, one can have a look at the Ghorasal Rail Bridge over the Shitalakhya very close to Dhaka.)
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