Request for Proposal ( RFP ) for Engagement of Detailed Design Consultant ( DDC ) for" Providing services related to structural designs for New line, Doubling, 3rd & 4th line projects, Road Over Bridges and Road Under Bridges etc. including station buildings, FOBs, PF shelters and other ancillary structures" for projects of Construction Organization under CAO/ Con/ South, East Central Railway, Mahendrughat, Patna.