Beijing (CNN) -- A "sudden malfunction" brought the high-speed Beijing-Shanghai train service to a shuddering halt this week, the third incident to hit China's new state-of-the-art railway in four days.
Stranded passengers had to be picked up from the eastern city of Changzhou by a back-up train, delaying their arrival in Shanghai by almost three hours, Beijing railway authorities said. It was not clear what caused the malfunction.
On Sunday, 19 high-speed trains on the line were delayed after heavy winds and a thunderstorm caused a power supply breakdown in Shandong province, eastern China.
One frustrated passenger used her account on micro-blogging service, Sina Weibo, to describe the incident aboard her train. "The train just passed Taian. The weather caused power breakdown and the train is stopped for repair.
"The train is now in a bridge in some unknown location and it's tilted...We're not sure when the glitch can be fixed. The lights and air conditioning are off in the carriages. It's all-closed carriage and it's very hot."
Two days later, another power failure at Suzhou in Anhui province halted a further 29 trains on the line for two hours, causing massive delays at Shanghai's Hongqiao railway station, according to China's Ministry of Railways. This incident is still under investigation, China's state-run Xinhua agency reported.
China's railway authority said Wednesday that the recent power failures pose no threat to its operational safety, Xinhua said.
But news of the anxious passengers trapped in the trains quickly spread on the internet, prompting people to question the safety of the trains, which entered service on June 30.
"This is horrifying. Accidents happened again and again. I don't want to try the high-speed train," posted one netizen on Sina Weibo.
However, a rail expert suggested the malfunction of the new bullet train might not be a surprise. "I think for the breakdown in Shandong, it was normal." said Sun Zhang, from Tongji University in Shanghai.
"It's mainly the weather problem. According to the operation standard of the high-speed railway, when the rainfall and wind speed exceed a certain limit, the trains have to be called off. This is normal."
China has invested more than 220.9 billion RMB ($34 billion) in the 1,318-kilometer (819-mile) Beijing-Shanghai rail link, which took almost three years to complete.
According to the Ministry of Railways, it is the biggest single investment by the government.
During a press conference before the formal launch of the high speed train, Hu Yadong, Vice Minister for Railways, assured reporters the service was "safe and reliable."
In response to the recent problems, the Ministry publicly apologized for "the inconvenience to the passengers due to the delay of the trains."
Shanghai's transportation department arranged extra transport for passengers who arrived late in the city, while refunds were given to passengers forced to cancel their trip.
But it may take the authorities more time to reassure the public the line is actually safe and reliable, according to Sun.
"The railway authorities should take lessons from these accidents," he said. "We need to improve the alarm system and the train design, so that the power system on the train can provide lights and air conditioning for longer."