Zhengzhou subway Photo: VCG

The subway operation company of Zhengzhou, provincial capital of Henan Province, faced controversy for what some said a slow response and "delayed" statement on a subway flooding which trapped more than 500 passengers and killed 12, while many netizens pointed to the unprecedented heavy downpour which was beyond everyone's expectations.

The rare, extraordinary downpour suddenly hit Zhengzhou on Tuesday, causing water to flood the Line 5's Wulongkou parking lot, Zhengzhou Metro said in a statement released on Sina Weibo Thursday afternoon. 

The flood water burst into the subway tunnel at around 6 pm, and the train had to stop between two stations with more than 500 passengers trapped inside, according to the statement.

Most of the passengers had been rescued, but 12 died despite emergency treatment, with another five hospitalized and in stable condition, read the statement.

The company said they are repairing the line and preparing to resume operations. 

The statement, which came two days after the tragedy, did not explain why the subway had not been suspended under the threat of the rainstorm or who would be responsible for the incident. Netizens called for further investigation to prevent similar tragedies in the future.

Line 5, which began service in May 2019, is one of the busiest subway lines in Zhengzhou. On July 20, 1.2 million trips were made in Zhengzhou subway lines, 374,200 of which were via Line 5, according to the Zhengzhou Metro's Weibo account. 

The subway lines in Zhengzhou, as well as others across China, are all built to handle once-in-a-century floods and earthquakes no greater than magnitude 7, media reported, citing subway engineers.   

Normally, subway lines would not be suspended if a few stations encounter problems. Some stations may be closed and passengers would be evacuated if water seeps in, but the lines would continue to be in service. It requires a certain ratio of the stations to be closed before the authorities make an announcement, according to media reports. 

Wang Hongwei, a professor at Renmin University of China's School of Public Administration and Policy, told the Global Times that Zhengzhou authorities must have prepared for the rainstorm, but the impact of the rain was way beyond their expectations.

It is still not clear whether there was a delay in the administrative procedure of the decision whether to suspend the subway, but a lesson we can learn from the tragedy is that related authorities in the Zhengzhou subway may decentralize power to the lower levels to ensure a quick response, Wang noted.