The first corridor of the Mumbai metro is likely to be the only elevated line, with the state planning to build underground lines for the other proposed corridors. Despite the higher cost involved in building underground lines, the Mumbai Metropolitan Region Development Authority (MMRDA) does not want to build elevated lines to avoid the problems of land acquisition, encroachment, traffic dispersion, and the resulting delays in time and cost.

"Other than the eastern suburbs, which have less congested areas, the ground realities of other parts of the city are such that an underground metro would be the way forward," said MMRDA chief Rahul Asthana.

The empowered committee on Mumbai Makeover, chaired by chief secretary Jayant Kumar Banthia, was also of the same view in its meeting in January.

While the first metro corridor, Versova-Andheri-Ghatko-par, is expected to be open for public next year, the contract for the second metro corridor, Charkop-Bandra-Mankhurd, is likely to get terminated due to delays. "If the contract is scra-pped, we will consider extending this line to Dahisar. We will also rethink on the decision to go elevated and chose a complete underground route," said a senior government official.