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.

This is not the first time that the Line 10 has had a problem. Two months ago, a train took a wrong turn due to signal failure, nearly leading to a collision.

The accident is an embarrassment for the Shanghai Metro operator because it had promised that the current signaling system would prevent trains from hitting one another. If this was the case, then why did such an unlikely accident occur?

It is noteworthy that the company that supplies signaling equipment to the Shanghai Metro Line 10 also made the signaling equipment for the high-speed line in Wenzhou.

No wonder people, including those in countries that might import signaling and other railway equipment, have doubts about what rail operators and suppliers have done to remedy design flaws.

We hope that the investigation team can provide a convincing explanation of the crash, and subway operators in other cities throughout China draw lessons from it and thoroughly examine their systems.

Subways have become the most convenient and fastest way for commuters to get around big cities considering increasingly serious traffic congestion. In fact, taking subways, as an environmentally friendly way to travel, has become the first choice of many people. But commuters' prerequisite is safety.

Currently, many of China's metropolises have launched ambitious plans to build subway lines. The State Council, China's Cabinet, has approved the metro plans of 22 cities, with a total investment of nearly 900 billion yuan ($140 billion).

During such rapid development, the quality of subway construction and safe operation is a big test for metro organizations and local work safety departments.

It is comforting that metro operators have paid due attention to security checks for the sake of passengers' safety. However, recently a number of Beijing's stations were reportedly having problems involving water seepage due to the use of substandard waterproofing materials.

Every precaution should be taken to resolve these and other potential safety problems so that the public genuinely feels safe riding on the nation's subway lines.

(China Daily 09/29/2011 page8)