Bridge, the viaduct and Port Machinery are all outdoors under the sun and the rain, so they were prone to rust and corrosion which will seriously reduce the safety factor.

• 大桥、高架、港口机械长期处于户外日晒雨淋，它们均极易生锈，很快就会发生锈蚀现象，大幅降低了安全系数。