Sliding security doors are being installed at Yong'anli station on Beijing's Subway Line 1, the oldest station in the capital without such protective equipment.

Unlike the full-height doors that reach almost to the ceiling in other stations, the ones used at Yong'anli are "half-height", or about 1.5 meters tall.

Running roughly along iconic Chang'an Avenue, Line 1 opened in 1971 and was put into civil use in 1981.

A passenger surnamed Ma applauded the installation, saying the doors will make the station safer.

"I was almost squeezed onto the track once, and it was pretty scary," Ma said.

From January 2014 to March, the city's subway system had 39 incidents of people jumping onto the rails. Of those, 21 happened on Line 1. Crowded platforms also brings concern to passengers and subway workers, according to a report in Beijing News.

Safety doors will be installed in all stations on Line 1 by the end of 2017, said a man surnamed Wang, who said he is responsible for door operation in the subway.

"There have to be numerous tests before the doors are ready, both automatically and manually," said Wang, who declined to give his full name.

In April, a pilot program started at Nanlishilu Station, but the more recently-built Yong'anli Station proved that the platform could withstand the weight of the doors, so it became the first station to receive the equipment, according to a report in Beijing Legal Evening News.

But another passenger surnamed Qin still had concerns.

"I'm afraid the doors may make it difficult for people to get on and off during rush hour," Qin said.

After developing for nearly half a century, the Beijing subway system now carries more than 11 million passengers daily, one of the busiest systems worldwide.

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Newly installed platform doors at Yong'anli Station on Beijing's Line 1 subway are being tested. Wang Zhuangfei / China Daily