Kolkata: RVNL started concrete deck launching between piers 326 and 327 of the Orange Line after 8pm on Friday and proceeded steadily throughout Saturday. Since the Chingrighata flyover has been shut and Nicco Park bound traffic is being diverted through a slip road built by RVNL, there were traffic snarls on the Bypass as cars moved from both Science City and Ultadanga sides. Traffic moved slowly from the point where the flyover starts till Salt Lake-Broadway crossing but was generally managed well by the cops.