The study into the Delhi - Mumbai high-speed line will be carried out by a consortium of China's Third Railway Survey and Design Institute Group Corporation of China and Lahmeyer International, India.
A consortium of Systra, Ernest & Young and local partner Rites will carry out a feasibility study on the Mumbai - Chennai corridor, while a consortium led by Ineco, Spain, has been chosen for the Delhi-Kolkata line.
Feasibility reports on all the three corridors are scheduled for submission in October 2016.
The China Railway Siyuan Survey and Design Group (CRSSD) is already working on a feasibility study for the 1754km Delhi - Chennai line.
In July the Japanese government offered to fund construction of the 505km Mumbai - Ahmedabad high-speed line provided 30% of the rolling stock is supplied by Japanese companies.