Pakistan Railways is all set to start rail operation with Afghanistan and awaiting green signal from Kabul, Railways Minister Sheikh Rashid Ahmed says. "We can steam off to Spin Boldak as soon as the green signal is given by Afghanistan," he said while speaking at a briefing given by the students of Muhammad Ali Jinnha University Islamabad on "Sky Train" project in the capital city. Ahmed said the Pakistan Railways is also ready to start train operation up to Kandhar city in Afghanistan. He said despite resource constraint the Pakistan Railways has been making all out efforts to upgrade the system between Iran and Pakistan. He invited investors especially from abroad and said the Pakistan Railways would welcome them to upgrade Pakistan's rolling stock on the route or elsewhere. The minister said that tenders for undertaking feasibility study for initiating a fast train between Rawalpindi and Islamabad would be floated in a month. Ahmed said the work on rail laying between Quetta and Gwadar is also being actively considered. He said the track would be laid according to international gauge standards.