Calls are mounting for Hong Kong’s embattled rail operator, which has outlined specifics of a fare freeze for the coming year, to offer more substantive measures for passengers struggling amid the coronavirus pandemic, including halving ticket prices for three months.The MTR Corporation on Thursday said it would hold the line on pricing in the year ahead, deferring a 2.55 per cent increase to which they would normally be entitled after negative growth in household income triggered a mandatory…