The MR pressure pipe is an important component of the brake system and in the operation of the automatic sliding doors.

However, though the train had resumed the journey after the fault was repaired. It came to a halt in a tunnel near Shymabazar station. The train was held up in the tunnel for nearly 20 minutes.

After the train reached Shyambazar platform at 10.23 am, the rake was examined and deemed unfit for commercial use by metro officials. The passengers were requested to disembark and the rake was taken to the Tollygunge shed.

“Nine pairs of trains in both the up and down sections had to be cancelled,” said Pranab Dutta, spokesperson for the Metro Railways. Meanwhile, the hour-long disruption of services resulted in serpentine queues at the ticket counters, coaches and stations, even in the afternoon.

Commuters said that the crowds also disrupted closing and opening of the sliding doors.

The technical fault was attributed to the older rakes, many of them over two decades old. The Metro Railways operates 12 rakes for commercial purposes (of a total of 18 rakes) between the 17 stations from Dum Dum to Tollygunge.

The Metro Railways authority plans to increase their rake holdings to 29 rakes.