A mandatory safety clearance for the commissioning of the full stretch of East-West Metro (Green Line) arrived last week, but with a rider.

When trains run on the full corridor between Howrah Maidan and Sector V, they will run on the manual mode, which will take more time to end the journey, officials said.

The 16.6km East-West Metro corridor is now functional in two sections — between Sector V and Sealdah and between Howrah Maidan and Esplanade. The 2.5km Esplanade-Sealdah section — which has seen four incidents of water leakage and soil subsidence since 2019 — is finally ready.

“Until recently, trains ran between Sector V and Sealdah in the automatic mode. All that the motorman had to do was press the start button and close the doors at stations. On the other section, between Howrah Maidan and Esplanade, trains ran in the manual mode. It was driven by a motorman,” said a Metro official.

“Even in the manual mode, there is a minimum gap of 50m between two trains on the same section. The driver cannot breach the gap, nor can he exceed the prescribed speed limit. In case he tries to, emergency brakes will automatically apply,” the official said.

Sumeet Singhal, commissioner of railway safety, Northeast Frontier Railway Circle, inspected the Esplanade-Sealdah section last Sunday. The CRS clearance came on May 5.

The date of commissioning of the 2.5km section, which will effectively make the entire 16.6km corridor between Howrah Maidan and Sector V functional, has not been decided yet.

But when it happens, trains will run on the entire stretch in the manual mode, said an official of the Kolkata Metro Rail Corporation, the implementing agency of the East-West Metro.

“Making the entire section ready for the automatic mode will take another six months at least. Using two separate software programs to run trains on the full corridor does not make sense. So, for now, when commercial services begin, trains will run between Howrah Maidan and Sector V in the manual mode,” said the official.

Both the manual mode and the automatic mode are parts of the communications-based train control system, which divides the corridor into moving blocks.

The manual mode is called the automatic train protection movement (ATPM). The automatic mode, or the automatic train operations (ATO) system, is an advanced version.

“A train running in the manual mode will take between 35 and 37 minutes to complete one trip between Howrah Maidan and Sector V. In the ATO mode, a train will take five to seven minutes less. That can help in increasing the frequency between two trains,” said an engineer.

When commercial services start, there will be an interval of around eight minutes during peak hours and 10 minutes in non-peak hours, sources said.

Since the CRS nod, trains are running on both sections in manual mode. After commercial services, the trial runs on the entire section are also being done in the same mode.

Six-coach rakes are used in East-West Metro, compared to eight-coach trains used in other corridors. The East-West rakes are manufactured by BEML. Hitachi is the technology partner handling the signalling system. There are 14 trains in the operational fleet as of now.

“Eight of the 14 trains have already been upgraded with the new ATPM software. It will take two more weeks to do the same on the six remaining trains. The ATO mode is being disabled for now on all the trains,” said an engineer.