"We have decided to go ahead with the metro train project instead of the monorail," Choudhary told media persons here.
The department was also pondering over a monorail project for the state capital.
Choudhary said the metro train project will be completed in four phases, and the Patna Metro Train Corporation will be set up before Aug 15.
An interim report of the project would be sent to the union urban development ministry soon, he said.
The Rail India Technical and Economic Service (RITES) will conduct a survey for the construction of the metro in Patna.
The Bihar capital is home to more than two million people, and congestion is a serious problem with the city's overcrowded lanes.