I was first introduced to proper escalator etiquette when I was working as a journalist covering the handover of Hong Kong 20 years ago. One day, as I sat exhausted in front of the TV, a strange commercial flashed onto the screen: It was a long clip of a humming escalator, onto which stepped a young man who slowly, mesmerizingly, inched his way to the top. Utterly clueless as to what it meant, my mind was illuminated by the final marquee across the screen: “Can’t you walk?”

The moral obligation for young and able-bodied people to walk up escalators has been ingrained in my mind ever since then. That little piece of common courtesy, I always thought, is essential to keeping the flow of traffic moving and providing more space for the less mobile. Even now, as I snake my way up Shanghai’s crowded subway escalators, I’ll sometimes cast a pointed glance at those I pass: “Can’t you walk?” I think to myself.

China’s cities have long cast fawning glances at Hong Kong, learning from its success in managing its vibrant service industries and cramped urban infrastructure. That which is common practice in Hong Kong has come to be seen as common practice across the Chinese-speaking world — something for which the mainland has developed a voracious appetite, given its decades of export-driven economic growth.

In 2006, the Mass Transit Railway Corporation, which maintains Hong Kong’s vast subway system, changed tack and started encouraging passengers to stop walking on the left and standing on the right, citing risk of injury from the sharp-edged moving stairs. Instead, the organization encouraged passengers to stand and hold the handrail, no matter which side of the stairs they were on.

This particular move did not catch on across the mainland, however, especially in Beijing, which was busy preparing for the 2008 Summer Olympic Games. Since 2002, when the city was vigorously sprucing itself up ahead of the huge influx of visitors, Beijing has been asking its idler subway passengers to keep right, leaving the left side free for others to walk.

Walking left made a dent on life in Shanghai when the city hosted Expo 2010, an international fair attended by 73 million people. Unlike the 16-day sporting event celebrated in the Chinese capital, Shanghai’s worlds fair lasted six months and drew a constant stream of visitors into its already overburdened subway system. As a result, the authorities encouraged everyone to walk on the left and stand on the right. Nowadays, most of China’s subway escalators have a thick yellow line painted down the middle to reinforce this rule.

As part of a publicity campaign from the city’s propaganda machine, primary schoolers were enlisted during the expo to stand at the end of subway escalators, chanting slogans like: “Walk left, stand right! Be a civilized Shanghai citizen!” Local press also encouraged youngsters to teach their parents how to behave on escalators. My son, who was 9 years old at the time, later told me the practice had been written into the moral education textbooks of Shanghai’s 500,000 primary school students.

But the tide was already turning. Guangzhou, the third mainland Chinese city to build a metro system, stopped promoting its “walk left” policy about a decade ago. Shanghai abolished this moral standard in 2013. Zhang Lexiang, deputy secretary-general of the China Elevator Association, said that the U.S., Canada, Japan, and South Korea had all revoked the policy on the grounds that it made passengers more vulnerable to accidents. Zhang cited the fact that escalator steps are 7 to 8 centimeters higher than normal staircases, and are therefore far from comfortable for people to walk on.

Most recently, a decision made by the subway authority in Nanjing, capital of eastern China’s Jiangsu province, caught the public’s attention. In December last year, the municipality filed a controversial motion calling for a halt to the practice of walking left, dismissing it as a safety hazard and claiming that 95 percent of its subway escalators were worn-down on the right-hand side.

Indeed, more perceptive passengers might have noticed that subway stations across the country have changed their public announcements, no longer encouraging passengers to stand right and walk left, but instead offering safety precautions like “Stand firm and hold the handrail.” Such an about-face has even made waves on Chinese microblogging site Weibo, on which 2.55 million users posted or shared a hashtag advising people to abandon the former practice.

How to behave on subway escalators interests such a wide audience because 43 cities on the Chinese mainland are either operating or building subways, and among these only four of the largest — Beijing, Shanghai, Guangzhou, and Shenzhen — run lines in excess of 150 kilometers, used by citizens long acquainted with subterranean travel. The succession of municipal government flip-flops on the issue of whether to stand or walk has left many people confounded as to what is expected of them, and has even become a safety issue in its own right.

Despite the government’s advice, most people are still stubbornly sticking to established escalator etiquette. A joint survey conducted in 2015 by state agency China News Service and Data100 Market Research found that more than half of respondents still walked left on escalators, while 30 percent said that they would consider walking up them, depending on the amount of foot traffic. Only 16.4 percent of people reported that they never felt it necessary to walk up the left side of an escalator.

Escalator manufacturers, subway operators, and safety inspectors are all divided over the issue. Chen Kexin, a spokeswoman at the Guangzhou Metro Group, said, “It’s an industry consensus not to promote the idea of standing right and walking left on escalators.” Chen added that safety inspections indicated that walking on escalators wore them out more quickly.

In contrast, a spokesperson for Beijing Subway Ltd., the authority for the city’s metro system, said that although the practice of walking left adds to escalator fatigue, it is not a major issue as long as maintenance is carried out frequently. An average of 8.27 million people traveled by subway each day in the Chinese capital last year; any abrupt change in passenger behavior, the spokesperson believes, would be detrimental to public order.

Meanwhile, Tang Xiaobing, vice president of Kone China, the largest escalator supplier in the world, said that it is unfounded to allege that standing predominantly on the right will wear down escalators more rapidly. Since escalator wheels are only a meter apart, he said, which side passengers stand or walk on does not matter. Design-wise, escalators are safe enough to weather the impact of walking left unless their wheels are of poor quality, Tang concluded.

China is home to one in three of the world’s elevators and escalators. In 2016, accidents on them claimed 41 lives across the country. While there are no figures breaking down the causes of individual fatalities, most accidents were linked to poor maintenance, as service companies chasing wider profit margins cut back on doing thorough work. Another reason, as Zhang of the China Elevator Association has argued, is that most subway stations in China use light escalators designed for department stores instead of the much more expensive heavy-duty models required in mass transit systems.

Both of the above scenarios carry potentially fatal consequences when accidents strike, and perhaps that is why officials and subway operators are increasingly wary of escalator fatigue and keen to play down the supposed moral incentive for passengers to walk left: After all, major cities like Shanghai are now practically inaccessible without taking an escalator or two. Yet for me, dismissing the moral grounds for walking left will only be fruitful if it allows officials to focus on the more pressing issue of ensuring that passengers are truly safe on subway escalators.

(Header image: Commuters use escalators on the Shanghai subway, Nov. 4, 2013. Wang Chen/Sixth Tone)