Who can approve Railway and ROB drawings of DFCCIL, RVNL, PSUs and Zonal Railways?

Approval system of railway bridges in Indian railways
Approval system of Rob girder drawings in Indian railways
Drawings of RVNL, DFCCIL, psu and zonal railways
Rail Vikas Nigam limited
RVNL
Dedicated freight corridor
DFCCIL
Railway bridges
Railway bridge design
How to read structural drawings
One of the most detailed model railroad
Why constructions takes so long
Bridge girder fabrication
History of railways in the world
Highway construction basic knowledge
All about trains
Road under bridge construction
How were bridges built in the past
Basic construction materials
Steel
Structural steel
How bridges are made
How bridges are constructed
How to understand bridge. Engineering
Understanding basics of bridge construction
Understanding basics of railway bridge
Understanding basics of a highway bridge