If the plans are finalised and a private party comes forward to foot the bill, trains will run at up to 350 km/hour along these corridors. Other routes, where similar proposals have been made, are Delhi-Amritsar via Ludhiana, Mumbai-Ahmedabad and Chennai-Bangalore.

While the corridor between Delhi and Amritsar may take Rs 60,000 crore to build, the one between Mumbai and Ahmedabad is expected to cost Rs 75,000 crore. The corridors from Howrah are expected to cost as much. The costs will be high as everythingrom sleepers, tracks, signals and rolling stock will have to undergo modification.

"The entire stretch will have to be fenced off and there can't be any crossings. A collision even with a man or a cow, at such a high speed will be catastrophic for the train. Our tracks cannot withstand such high speed and will have to be replaced. New locomotives and rakes will have to be brought in. Power consumption will also go up," a senior railway officer said.

But there are officials, who are not sure whether the returns will justify such huge investments. Passenger fares will be considerably high and investors would want to put property in and around the stations into commercial use.