The Shenzhen subway had a similar accident in December, also involving an Otis 513 MPE. Inspectors have not found any connections between the escalators in Shenzhen and Beijing, because their specifications and structures are different, said Li of Otis China. The specifications were based on the customers' requirements, she said.
The customer in Beijing denied there is such a difference.
"I don't know what you mean by specifications," said Yang Ling, spokeswoman for Beijing MTR Corp. "We have already released information on the specifications of the malfunctioning escalator (in Beijing) on our official website."
A China Daily reporter looked through all five escalator accident briefings and a news conference transcript posted on the company's website July 5-8, but did not find that information.
China has adopted safety rules for the construction and installation of elevators, escalators and the horizontal conveyors often seen in airports. Chinese technical standards are equal to European standards (EN81-1:1998 for elevators and EN115:1995 for escalators), but the passenger flow at Chinese subway and railway stations is much greater than that in Europe.
Every day, more than 7 million journeys are made on 14 Beijing subway lines, which run a total of 336 kilometers, Li Xiaosong, spokesman of the Beijing Municipal Commission of Transport, said at a news conference.
Besides traffic flow, local area characteristics and environment are important considerations in setting safety standards for elevators and escalators, said an expert at the Guangdong Elevator Technology Institute who asked to remain anonymous. For example, compared with European cities, Beijing needs sturdier elevators and escalators because it is windier, dustier and more polluted here.
"The safety standards for elevators and escalators in China should be set higher than the European standards, so that the standards will conform more smoothly to the Chinese conditions," the expert said.
The standards are only a threshold for market access, Zhang said, but an escalator of good quality far exceeds the basic standards.
"If a truck with a loading capacity of 20 tons and above is called a heavy-duty truck, do I need to buy a truck that can carry a maximum weight of 50 tons or 100 tons?" he said. "It's a complicated calculation based on many factors."
Experts said that because safety standards do not meet the actual demands of public transportation in China, it is hard to simply blame either manufacturers or operators.
The government is tightening its supervision of inspections of escalators and elevators. Zhao Hui, who lives in an Air Force residential compound in Beijing, noticed that the safety test certificate posted in an elevator of her building had expired. The next day, she ran into a person changing the certificate, who explained the elevator had been repaired in February but the bill hadn't been paid. Now with the government checking elevators, the managers had to replace the certificate in a hurry.
Elevators should be cleaned, lubricated and inspected at least once every 15 days, according to safety regulations for special equipment. In addition to the 478 registered elevator manufacturers, about 4,500 service companies have obtained permits to install and maintain elevators.