Eversafe Marine is proud of his own contributions to the bridge construction: successfully launched two portable steel cofferdams constructed to facilitate bridges piers construction with marine airbags. The seventh cross-Yangtze River bridge of Wuhan City is the largest three-tower cable-stayed bridge with 616 meters of main span. This 4.7-billion-RMB bridge opened on January 2, 2011.
Those two cofferdams weigh 2580 and 2800 tons. The biggest one measures by 57 m long, 35 m wide and 16 meters high, covers a twice time area of the basketball court and is higher than 5-floor building.
Small cofferdams are often launched into river by crane and winches but for more than 2,500 tons weight there are many limitations of deploying cranes to launch. Eversafe Marine as the professional engineering company was invited to research feasibility of cofferdam launching with marine airbags from natural dirt ground. If marine airbags launching method is possible then the cofferdam can be built on river bank completely which can save much investment and time.
After research and calculation, Eversafe Marine believed the cofferdam launching with marine airbags is safe. To avoid any possible deformation of cofferdam and ground sink, Eversafe team designed the most safe launching plan from underlay of cofferdam to launch ramp angle adjustment.
When the launch time came, the cofferdam was moved forward 10 meters to near the water, then the pulling back ropes were cut down. At that time huge cofferdam began to move with rolling airbags by gravity slipping force, it splashed big spoondrifts when got into water at last floated by its own buoyancy smoothly. Then tugs towed cofferdam to its right position.