With the growing flow of passengers into the urban subway system, Beijing is experiencing a greater incidence of minor malfunctions.

Beijing's subway trains have broken down 39 times so far this year, logging at least one failure per week, and 18 of them were caused by signal failures, according to Beijing Youth Daily report on Monday, which calculated the failures based on information posted on the Beijing subway's micro blog.

But according to Jia Peng, spokesman for Beijing Mass Transit Railway Operation Corp, which operates 14 lines, the data are unreliable as they were attained in a non-scientific way.

The dependability of the Beijing subway has been a top priority this year for the Community of Metros, an international organization of subway systems, Jia said, adding that the 31-member authority on metros has set an officially recognized standard for operational reliability - the distance the metros run in the period between two accidents that have caused a delay of more than five minutes.

From that perspective, the distance between incidents in Beijing reached 426 kilometers, topping the list until now.

But there seems to be widespread agreement among passengers that the system has problems.

Six out of 10 passengers that China Daily randomly interviewed on Line 2 on a recent afternoon said they had run into delays at least once.

"I was forced to take the bus after finding crowds in the station at rush hour," a man surnamed Sun said, recalling his trip on Aug 28 when a signal failure caused a train on Line 10 to evacuate the passengers at around 5:50 pm.

But, Jia said, "The 'breakdowns' passengers talk about are not significant enough to be described with the technical term 'breakdown'." What the public calls a breakdown may be only a minor malfunction that can be resolved within minutes, he said.

Door malfunctions happen almost every day, he said, because passengers push on them when they squeeze onto crowded cars or stop the doors from closing with purses or other objects so their friends can get on.

"These can be resolved within minutes, but they still cause delays," Jia said, adding that with the large passenger flow and expanded numbers of lines, delays now affect tens of thousands of people.

By the end of August, the 14 lines under the management of the corporation transported about 8.49 million passengers a day, he said.

"To satisfy the large passenger demand, the short-term solution is to shorten the interval between departures, and the long-term solution is to build more train lines," Jia said.

But it's not the best practice to go to shorter intervals, because that will make it harder for the signal and control systems to maintain high-quality operations, said Li Xian, deputy director of the Beijing Transportation Research Center.

She suggested that the operating companies use broader and longer trains and move to flexible arrangements of trains for different hours and stations.

zhengjinran@chinadaily.com.cn