We are thus well ahead of other metro rail systems in India as far as non-ticketing revenue is concerned,” sources said. “Once the whole space is rented out, the income from non-ticketing revenue will exceed the income from ticket sale. The daily operation and maintenance expense works out to around ?30 lakh,” metro sources said. The income from non-ticketing sources includes that from the sale of advertisement space on metro pillars and exterior of 13 trains (?2.92 crore per year). The metro agency’s other sources of non-ticketing revenue are ‘station-naming rights’ in which firms that win the bid can have their names as suffix of station locations, and station inter-connection rights, in which shopping malls and high-rises can build direct access to metro stations..