A glitch in the communications-based train control system disrupted services on the East-West Metro, or the Green Line, on Thursday morning, the second such snag in two consecutive days.
The duration of the disruption was shorter than that on Wednesday, when direct Metro connectivity between Howrah Maidan and Sector V was shut for over two hours.
On Thursday, trains did not run between Esplanade and Sealdah for around 30 minutes. The carrier ran truncated services between Howrah Maidan and Esplanade and between Sealdah and Sector V.
“The problem was detected at 10.30am. Full services between Howrah Maidan and Sector V resumed around 11am,” said a Metro official.
It was a glitch in the communications system that controls train operations on the Green Line. Before the Esplanade-Sealdah link was commissioned, the entire corridor was integrated into a single CBTC unit. But there are two main components of this system, one between Howrah Maidan and Sealdah, and the other between Sealdah and Sector V.
“The system between Howrah Maidan and Sealdah was not able to communicate with its counterpart between Sector V and Sealdah. That is why we had to resort to truncated services. The services between Howrah Maidan and Esplanade were operated manually. The services between Sealdah and Sector V ran in the automated mode. The glitch posed challenges in the section between Esplanade and Sealdah,” said the official.
Wednesday was a state holiday, but Thursday was a working day, and the glitch caused problems for many.
On Wednesday, direct connectivity between Howrah and Salt Lake was suspended from 10.35am to 1pm. The service resumed after the implementation of an alternate, back-up mode. After the commercial services ended on Wednesday night, a team of senior Metro officials and experts from the company that designed the signalling and telecommunication system stayed put at the control centre in Central Park for several hours to trace the problem.
“The glitch that happened on Thursday was not as severe as that on Wednesday, but of a similar nature. In the CBTC system, the entire corridor is divided into several components. Trains make one, tracks make another, and the signalling and telecommunication system make another. The communication gap jeopardised the synchronised communication between all the components,” said an engineer.
A Metro official said: “This system was introduced in phases and later integrated into one unified structure. These are teething problems that are not completely unnatural. We handled it better on Thursday than we did a day ago.”
The older north-south corridor, or the Blue Line, which has been plagued with repeated disruptions, fared reasonably better on Thursday.