NEW DELHI: Reputed companies from six countries, including France, Germany, Italy and China, have entered the race to become part of Prime Minister Narendra Modi 's pet Diamond Quadrilateral bullet train project.Twelve international companies are bidding for conducting the feasibility study for the three corridors of the Diamond Quadrilateral high-speed rail network project, said a senior Railway Ministry official.Feasibility study is being sought for high-speed rail corridors between Delhi and Mumbai, Mumbai and Chennai, and New Delhi and Kolkata, which are part of the Diamond Quadrilateral project.Four companies from China, including Siyuan, DB International from Germany, Systra from France, Sener from Spain and Italser from Italy, besides one from Belgium, have joined the global competitive bidding to bag the survey contract.However, the official said that one company will be allowed to do the survey for one corridor only in the Diamond Quadrilateral project.The bidding was opened this week and the winners will be decided within four months by July, said the official, adding that the feasibility study for the three routes is estimated to cost about Rs 30 crore.Currently, the superfast Rajdhani Express covers the distance between Delhi and Mumbai in about 16 hours. With the introduction of the high-speed train, the travel time is expected to be reduced by almost half.Similarly, the travel time between Delhi and the other metros will be reduced with the introduction of bullet trains.At present, China is undertaking feasibility study of the Delhi-Chennai route, also a part of the Diamond Quadrilateral project.The Rs 2 lakh crore Diamond Quadrilateral project aims to drastically reduce the travelling time between the metros with the introduction of the high-speed trains, which will run at speeds of about 300-kmph.Besides, a feasibility study is in progress by the Japan International Cooperation Agency JICA ) for the 534-km-long Mumbai-Ahmedabad high speed corridor project, which is estimated to cost Rs 63,180 crore.