At least 18 bridges have collapsed on the mainland since 2007, killing 135 people, according to the records of the State Administration of Work Safety. Most had been in use for less than 15 years.
The latest victims were three people killed on Friday when a 100-metre section of approach ramp snapped a bridge in Harbin , Heilongjiang .
The true number of collapses could be higher because some cases are classified by the work safety agency under other categories such as natural disasters.
Poor-quality construction is seldom singled out for blame by local authorities, though the collapse of a just-completed bridge in Fenghuang , Hunan , in 2007, in which 64 people were killed, is an exception. Instead flooding, overloaded vehicles or cargo ships hitting bridge supports are more often blamed.
Huang Yusheng , secretary general of the Harbin city government, said yesterday that the approach ramp that collapsed on Friday was not regarded as part of the main Yangmingtan Bridge. Even if it was found to be of poor quality, it would have "nothing to do" with the landmark project.
Safety experts, however, have less confidence in bridge quality than the government.
Dan Danhui , associate professor with Tongji University's bridge safety department in Shanghai, said the construction of many bridges had been rushed. The situation had become particularly severe in recent years as the government put huge investment into infrastructure development to boost the economy, create jobs and keep gross domestic product growth high in the face of a global recession.
"A few years ago China had only about 500,000 bridges. Now we have more than 700,000," Dan said. "No country has ever built hundreds of thousands of bridges in just a few years. With such a huge number of projects going on … I am not surprised to see an increasing number of reports of collapses."
Dan's concern about the rush to build bridges is shared by other industry experts. Bridge scientist Chen Zhaoyuan , a Tsinghua University professor and a member of the Chinese Academy of Engineering, published an open letter last year warning many good practices designed to ensure bridge safety had been abandoned during the rush. "Are we building too fast?" he wrote.
He said that more than 10 years ago, the idea of carrying out surveying, design work and construction simultaneously was rightly regarded as irresponsible, but was now "common practice". Such haste would greatly undermine a bridge's safety, but government officials in charge of the projects often specified a deadline for completion within their term of office, Chen wrote.
Dan said the philosophy of bridge designers had also shifted. "Bridge designers were less confident, and thus more fearful, in the past," he said. "Today's design philosophy is to find smart ways to cut costs while meeting the minimum safety requirements."
Corruption had also led to poor-quality construction, Dan said.