Situated at the junction of Yichang and Enshi in Hubei Province, Sidu River Super Suspension Bridge is a control bridge project of Shanghai-Chongqing Expressway. The main span of the bridge is 900 meters. The height difference between the top of the tower and the bottom of the canyon is 650 meters. The bridge deck is 560 meters away from the bottom of the canyon, which is equivalent to the height of 200 stories. It is the longest suspension bridge built in the deep mountain canyon in China at present. It is also the first mountain super-large suspension bridge with a span of more than 900 meters in the world. It is 307 meters and 290 meters taller than the world's tallest bridge, the Miyo Bridge in France. It is known as "the world's first high suspension bridge" and "flyover in the sky road".
The inspection on that day was mainly aimed at the inspection of the connecting rod pin axle of the bridgehead tower on the right side of Sidu River Bridge in Yichang. The Sidu River Bridge is a special structural bridge with 900 meters of the main span and steel truss suspension structure. The pin axle tested is the main component connecting the main tower and the connecting rod of the tower. During the inspection, the professional inspectors hold the ultrasonic flaw detector in hand and move back and forth on the pin axis of the tower connecting rod through the metal probe attached to the flaw detector. The relevant data are recorded and transmitted to the computer in real-time. The whole detection process lasts for a shorter time and does not cause any damage to the bridge structure. It is an efficient and safe detection method.