IT IS FRUSTRATING THAT WHILE WE ARE STILL waiting for an explanation of the high-speed train crash in Wenzhou, Zhejiang province, in July, we receive the startling news that a Shanghai subway train hit the back of another train on Line 10 on Tuesday.

Fortunately, no one was killed and most of the 270 injuries were not serious.

An investigation team led by the city's work safety department has promised to provide a detailed explanation of the crash's cause.