Salt Lake: Platform screen doors meant to act as a barrier to an accidental fall or a suicide attempt are being installed at Karunamoyee station of the East-West Metro, marking the Calcutta debut of a safety feature integrated into mass rapid transit systems across Asia and Europe.

A team of 48, including engineers from China, has been at work for a few weeks to install the platform screen doors that arrived from Shanghai in July.

In the first phase of installation, the six elevated stations between Sector V and Stadium will get screen doors on the platforms.

The Chinese consortium of Zhu Zhou CRRC Times Electric Co Ltd of Hunan and Panasonic Manufacturing (Beijing) Co Ltd has manufactured the electronically operated doors and optimised them for crowded platforms and trains.

Platform screen doors from floor to ceiling will be installed at the underground stations from Sector V to Howrah Maidan.

Delhi Metro has long had platform screen doors. The technology used in Calcutta is also a feature of Metro platforms in Copenhagen, Sydney and Wenzhou in China, among other cities.

Door mechanism

A platform screen door assembly typically comprises three sections. The automatic sliding door is the main function. The train's door is aligned to the automatic sliding door and are meant to open together.

"Every automatic sliding door will have handles to enable a passenger to open it manually if it doesn't work automatically," said Roger Zhu, mechanical and design manager at CRRC Times Electric.

He and his team are providing technical support for the installation.

A fixed panel supports the sliding doors. Adjacent to it is the emergency exit that has a horizontal lever. If the sliding door doesn't open, the train will align its door with the emergency exit so that passengers can pull it open to disembark, an official said.

In the event of an emergency, passengers will be evacuated from the track-side door for faster dispersal. They will be taken out through the opposite platform and the emergency gates on the other platform will be opened.

The platform units that are being installed are 2m wide and 1.7m tall. The platform screen doors for underground stations will be 2.7m in height. The doors are made of tempered glass like those used on mobile-phone screens. This glass is four times stronger than the regular material.

Control panel

At the base of the fixed panel is the control panel from where the function of the platform screen doors is controlled. This section has a door-locking unit, power junction box, electromagnetic lock for automatic opening and closing and a converter for controlling power supply. It also has a unit to monitor the functioning of the doors of all six coaches.

Designed for crowds

The doors have sensors to allow the doors to reopen even if there is an obstacle within 6mm of the two slides. This means if a finger is between the slides, the door will reopen. "This system is designed to handle crowding on trains in Calcutta," an official said.

The north-south Metro line has been in operation for more than three decades.