China's railways ministry has promised to fix problems with power outages and other malfunctions that have plagued the showcase new high-speed line between Beijing and Shanghai since it opened last month.
Railways Ministry spokesman Wang Yongping apologised in an online chat posted on the ministry's website, acknowledging that the 820-mile line which began commercial operations last month has experienced several dozen power outages in the past week.
He appealed for public understanding, saying that summer thunderstorms and winds have caused some of the problems.
The Beijing-Shanghai line was opened to great fanfare on June 30, the eve of the 90th anniversary of the founding of the ruling Communist Party.
Its problems are awkward given the trophy project's purpose of demonstrating China's prowess in advanced technology.
The top operational speed for the line's trains is 186mph. The speed was cut from the originally planned 217mph after questions were raised about safety.
On Wednesday, a high-speed train headed to Beijing broke down due to a failure of its transformers, dropping the speed to 100 mph and passengers had to change trains because of concern the slow speed would disrupt the entire line's operations, Mr Wang explained.
"These malfunctions did not cause any major safety risks, but they have truly affected the railway's operation," he said.
Despite the troubles, the railway carried an average of 165,000 passengers daily from July 1 to 13, with a peak of 197,000 people, he said.
Official plans call for China's bullet train network to expand to 8,000 miles of track this year and 10,000 miles by 2020.