Chennai Metro - Why introduce a new gauge?

During the early seventies, the Central goverment decided that Calcutta and Madras needed underground trains to cope with a rapidly deteriorating traffic situation. The Indian Railways offered to construct one corridor along the city's eye sore Buckingham canal alignment using a low cost cut and cover method. This would have achieved two objectives - eliminate the large open sewer the canal had become while providing Madras with a nice underground metro.

Calcutta's project got under way. Due to a slow moving TN bureaucracy and subsequent financial constraints the Railways amended their original offer to a cost sharing project with the TN goverment having to fork out some of the money. The TN government refused point blank and the project never made it. Eventually some bright spark in the TN government decided that it would be significantly cheaper to have an elevated railway instead of an underground system and tried to persuade the Railways and Central govt to go ahead as committed with this cheaper project. Eventually the TN government had to share the revised project costs anyway and the people of Chennai are left with the hideous monstrosity that passes for the "parakkum rail" aka MRTS while the canal features on foreign TV stations as an example of India's extreme poverty and dirt.

While no TN government tried to improve Chennai's traffic woes, it was again left to the Central government via Sreedharan of Delhi Metro to initiate a Metro for Chennai. A previous TN government tried to convert this project from an underground to an elevated monorail system. Anyone who has visited the Jurong bird park in Singapore or the Sydney Darling Harbour Circular Quay systems can understand how monorails serve only low traffic volumes over short distances and are no answer to the large traffic volumes for a city of Chennai's size. Fortunately for Chennai that monorail project disappeared with the person who proposed it. The proposed underground metro project has most sections above ground and is thus fundamentally flawed. Now the current TN government must understand that a previous Railways Minister caused irreparable harm to the Railways finances by embarking on a foolish Uni gauge project for the country. All of Chennai's suburban railways are on one uniform broad gauge. Then why introduce a new gauge system now? The proposed Chennai Metro on a Standard Gauge doesn't allow for inter operability or provide key operating efficiencies as the rest of the Railways suburban system is on BG.

I realise that most educated middle classes in Chennai travel in chauffeur driven cars and couldn't care less what public transport system was implemented. However, for those who do care this is an issue worth pursuing.