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Kolkata Metro. (Photo: Wikipedia)

The Purple Line metro services have utilized the electronic interlocking (EI) signaling system, enabling trains to operate concurrently on both up and down tracks.

The commercial services on the Joka to Majerhat stretch of the Kolkata metro will remain suspended for two days starting Wednesday, April 24.

The metro railway authority of the city shared the information through a press release. No trains would be running on this stretch on the Purple Line which connects the southwest parts of Kolkata due to signal upgradation work.

The suspension is expected to cause trouble to many commuters as the Joka-Esplanade corridor is one of the busiest routes of the city’s metro network.

“Due to some operational exigencies related to the conversion of the electronic interlocking (EI) signalling system to the CBTC signalling system, Metro services on the Joka to Majerhat stretch of the Purple line will remain suspended on Wednesday and Thursday. There will be no commercial services in the Joka-Majerhat stretch on these two days,” the official press release read.

Metro services on the Purple Line have been operating on the electronic interlocking (EI) signalling system, which lets trains run simultaneously on both up and down tracks.

The Kolkata Metro Railway Authority has decided to convert the basic signalling system on the Joka-Majerhat stretch to high-tech communication-based train control, known as CBTC. Thanks to the technology that uses telecommunication, now trains will run automatically.

Apart from the 8-kilometre-long Joka-Majerhat stretch of the Purple Line, the Orange Line linking New Garia with Kolkata airport will also get the CBTC signalling system. Siemens has been assigned with the work to install the automatic technology on both metro routes.

Instead of incorporating a new system, the basic electronic interlocking (EI) signalling system would be upgraded to the CBTC. As this was expected to be a long, complicated process, the metro authority would need a minimum of two days to complete the conversion work.

The Kolkata Metro Railways has already begun construction of the underground Mominpur-Esplanade stretch of the Joka-Esplanade Metro Corridor. The 6.5 km stretch from Joka to Taratala of the Purple Line commenced operation in December 2022.

The route was later extended to Majerhat and the stretch was inaugurated earlier in March this year. The entire Joka-Esplanade corridor covers a total distance of 15.08 kilometres in south Kolkata.