The proposed flying train service between Velachery railway station and St Thomas Mount railway station is unlikely to start immediately as final approval is still pending, officials said.
Railway authorities had earlier planned to launch the service from March 10 after completing safety inspections. However, the required safety clearance has not yet been issued.
A team led by the Railway Safety Commissioner recently inspected the track by operating trains and using trolleys to assess the safety of the line.
Officials said the inspection team has suggested that some additional work be carried out on the track before granting permission for regular train operations. The service will begin only after the work is completed and the safety certificate is issued.
Once launched, the Velachery–St Thomas Mount flying train service is expected to improve rail connectivity in South Chennai and help reduce traffic congestion in the area.