The leakage inside East-West Metro’s under-construction tunnel in Bowbazar last September has again indefinitely delayed the completion of the corridor, said a senior official of Metro Railway.

For much of last year, Metro officials had been saying that trains should run on the full course of East-West Metro (Green Line), between Howrah Maidan and Sector V, by early 2025.

At a news conference to mark 40 years of Metro Railway on Friday, P. Uday Kumar Reddy, the general manager of the facility, said he could not “commit” any deadline for the 16.6km corridor.

“The construction in that area (Bowbazar) is very critical. We really don’t know what exactly will happen. We are trying our level best to safely move inch by inch. So, it is taking time. Since it is in a critical situation, we are not able to specifically tell you the date on which we will be able to complete the work,” Reddy said.

On the night of September 5, underground water leakage triggered by Metro construction forced the evacuation of more than 50 residents from six homes.

It was the fourth accident at the Bowbazar construction site since August 2019. The leakage was arrested within 24 hours but it has since forced engineers to go slow again, said sources.

Asked about the work that remains, the Metro boss said on Friday: “There was a problem in the tunnels. The tunnels are being strengthened because of the water ingress. We want to make it as safe as possible. Once the work is complete, we will have to join two sections. The stretch has to be checked for signalling systems again. These are going to take some time.”

The east-west corridor is now operational in two phases — between Sector V and Sealdah (Green Line 1) and between Howrah Maidan and Esplanade (Green Line 2). The 2.5km stretch between Esplanade and Sealdah is the only under-construction section of the line.

Metro had earlier reported that a trial of the automatic signalling system, in trains and on the tracks, began on the Sealdah-Esplanade stretch on June 23. Railway sources said the tests on the east-bound (Salt Lake-bound) tunnel was almost complete.

Civil engineering work on the east-bound tunnel is also nearly complete. Trains running between Howrah Maidan and Esplanade are travelling through the east-bound tunnel to reach the depot in Salt Lake and come for commercial runs again.

The west-bound (Howrah-bound) tunnel is still far from ready. Tracks are yet to be laid on around 350m of the west-bound tunnel, sources said.

A Metro official, who requested not to be named, said: “We are hoping to finish civil engineering work in the Esplanade-Sealdah section by January 2025. Signalling tests should take another four to five months. After the signalling tests are complete, there will be a CRS inspection. It is unlikely before August-September.”

An inspection by the commissioner of railway safety (CRS) is mandatory before commercial runs.

Forty years

Metro Railway will turn 40 on October 24. From 3.4km at the beginning, Metro now covers around 60km and operates in four corridors.

“We aim to cover 90km by the end of 2025 and 130km by the end of 2027,” Reddy, the general manager, said.

“Metro has touched the lives of so many Calcuttans and we hope to continue doing that.”

On Friday, three short films on Metro Railway were screened. They showed the evolution of the carrier. Actors, musicians, sportspersons, industrialists and ordinary passengers were seen endorsing Metro. A special logo was also unveiled.

The carrier has lined up a series of celebratory events. A heritage walk, a new gallery at Esplanade station, a special ride on an old non-AC rake, souvenirs and the release of a stamp are in the pipeline.