Photo:IC

The Humen Bridge in Guangzhou, China's first large suspension bridge, resumed traffic at 9 am on Friday after a 10-day investigation into abnormal shaking which triggered widespread concern of a possible collapse.

According to videos posted by Pear Video and People's Daily, traffic ran smoothly on the bridge on Friday. 

Many vehicles were private cars with less than seven seats, and a driver said that the bridge was stable and not bumpy at all. Cargo ships were seen passing under the bridge on Friday. 

Experts invited to assess the abnormal shaking of the bridge reached consensus on Wednesday night that bridge management had taken anti-vibration measures and the structure of the bridge was sufficiently safe to resume traffic. 

The anti-vibration measures included installing an airflow-suppressing board outside the guardrail, adjusting the aerodynamic shape of steel box girders and installing water tanks to increase weight so the damping ratio can be increased. 

Experts analyzed the cause of the vibration, and believed the retaining wall (water horse) changed the aerodynamic shape of the steel box girder which induced the vertical vorticity of the bridge.

The bridge started to show signs of shaking on May 5, which led many netizens to worry it would collapse.

The expert team from the Ministry of Transport conducted a field inspection the next day, and the Guangdong provincial transport department invited domestic and international experts to assess the safety of the bridge. Results showed the bridge's structure is stable and the vibration did not affect its structural safety. 

Sun Zhang, a professor on transport and mechanics at Tongji University in Shanghai, told the Global Times these measures that changed its shape and increased its mass to prevent resonance will be effective. 

He said it's important to install a sensor on the bridge to warn of deformation and vibration. 

On the forthcoming typhoon season, Sun said that the bridge has withstood typhoons in previous years, and will not be affected this year either.