The south approach bridge of the Yanbai Yellow River Bridge is 593 meters long and requires 126 precast box girders of 30M×1.24M. According to the design requirements, two gantry cranes must be installed to meet normal construction production needs. In mid-August, the south approach bridge entered the girder fabrication stage. At six in the morning, Deputy Manager and South Bank Work Area Director Zhang Huilong led the assault team installing the gantry cranes to the south approach bridge construction site early, and carried out the first span hoisting construction according to the original plan.

       At around 10:30 a.m., this reporter hurried to the hoisting site together with Executive Deputy Project Manager Zhang Ge, Deputy Party Branch Secretary Li Kai, and Safety and Quality Director Duan Zhongrong. At this time, the gantry crane installation was already preparing to enter the second span sky-girder installation.

       The south approach bridge construction site is very narrow, with complex and special terrain and environment. To the south of the entrance is Lanzhou's main urban area, and to the north of the exit is the main bridge, connecting to Pier 0. Not only is Hongyun Runyuan Residential Community on the left and Tianqing Rhein Town Residential Community on the right; but outside the enclosure, the traffic diversion lane has pedestrians and vehicles flowing endlessly north and south, and the adjacent commercial street is even more densely packed with fruit and grocery stalls. The construction area behind the enclosure is about 580 meters long and 25.5 meters wide, and the inner width of the gantry crane is only 23 meters. Constructing within such a narrow range requires placing four large cranes in a square formation at the four corners, storing four spans of sky girders in a clockwise direction in the middle, and also placing two rotary drilling rigs and loaders, etc.: the site is narrow, there is a lot of mechanical equipment, cross-impact is great, and the construction difficulty can be imagined—no different from high-difficulty moves on an "acrobatics platform." Hoisting in midair over a bustling downtown, with internal complexity and external chaos, is a matter of life and death and is thrilling: the slightest carelessness or small mistake could lead to a catastrophic disaster.

       At 12:06, two large 75-ton cranes cooperated with each other like "Vajra War Gods" and began hoisting construction in the narrow site. Two hooks firmly grabbed the 23-meter-long sky girder weighing about 16 tons and slowly lifted it upward. The whistles directing the hoisting rose and fell amid the noisy city streets; and every whistle blew on the nerves of the on-site commanders and builders.

This reporter witnessed the scene on site: Crane No. 1 lifted a little, Crane No. 2 lowered a little; moved left a little, shifted right a little; swung forward a little, sent backward a little…… throughout the entire hoisting process, every fraction of an inch mattered to success or failure, and it was truly thrilling; like a seamstress threading a needle, not the slightest error was allowed. At 12:23, the first sky girder of the second span, weighing about 16 tons, was safely and smoothly put in place in midair, lasting about 17 minutes from start to finish.

At around 15:00 that afternoon, the last two spans of sky girders of the second unit were also successfully hoisted.

The photo shows the sky girder needle-threading hoisting site