NTES is the salt of Railfanning. IRI is the sugar. - Kirti Solanki

Indian Railways did suffer from the lack of investment since independence resulting in losing of Market share and there is no doubt about it.
One more fact is equally or even more relevant- that most of the investment made by IR was done without proper financial justification resulting in huge losses, very poor return on the investment which in turn resulted in poor revenue generation/operational surplus which in turn resulted in even lesser investment. This becomes a vicious circle leading to chronic shortage of internal generation of funds leading to grossly inadequate capacity augmentation. In this scenario, even if huge investment were made in past by taking loans, IR would have gone bankrupt due to inability to repay the loans. Many time...
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IR want interest free loans from govt to do expansion which can never be justified as in this case govt. of India will take loan which ultimately taxpayers have to repay.
Similarly if the huge investment being done in IR is not properly planned and implemented, it shall lead to much higher loan repayment, higher corruption and quick bankruptcy for IR instead of betterment. Although most of the investments are being channelised in doubling/multipling which are known to give higher financial rate of returns than GC/ new lines, but a lot needs to be done to ensure right prioritization of projects, timely completion, control the cost and to ensure top quality of construction.