Rakteem Katakey / New Delhi August 26, 2008, 0:52 IST Indian Railways, which are likely to post a cash surplus of Rs 31,000 crore in the current fiscal, should pay market rate for the diesel they consume, as they are one of the largest consumers of subsidised diesel that contributes significantly to the under-realisation losses, state-owned oil companies said in a letter to the petroleum ministry. If diesel is sold at market rates, Indian Railways, the world's second largest railway network, along with state transport undertakings and the defence forces