Design verification & validation, Supply, Installation, Testing, Commissioning, Supply of spares & special tools, Operations and Maintenance during two (02) years Defect Liability Period (DLP) and five (05) years Comprehensive Annual Maintenance Contract (CAMC) of Ventilation and Air Conditioning (VAC), Tunnel Ventilation System (TVS), Associated Electrical and integrated SCADA works for eight (08) Underground stations in Corridor-4 (C4) from Lighthouse to Kodambakkam station, including C4 related TVS SCADA works at Thirumayilai station and Integrated Station Management Systems (ISMS) at OCC and BOCC.