Vehicles Leave “Pits”

　　On the afternoon of November 20, the reporter came to the Bengbu Daqing Road Huaihe River Highway Bridge. The main bridge deck had just completed a “skin graft” operation, and the construction workers had recently withdrawn, leaving a brand-new asphalt surface.

　　As the third bridge over the Huaihe River in Bengbu, the Daqing Road Huaihe River Highway Bridge officially opened to traffic on December 31, 2012. Official media reported that it adopted a double-tower, double-cable-plane self-anchored suspension bridge, and the steel box girder incremental launching construction technology and many other aspects were the first in the province.

　　Driving on the wide and flat bridge deck, passing drivers naturally felt comfortable.

　　However, the good times did not last. Around September this year, many ruts gradually appeared on the bridge deck. As the ruts deepened, many small depressions formed, and even large cracks appeared in some places.

　　Experienced drivers reported the situation to the Bengbu Municipal Transportation Bureau. “Ruts and small depressions will accumulate water, which is most likely to freeze in winter, resulting in a low safety factor.”

　　Finding the Cause

　　The Bengbu Municipal Transportation Bureau decided to investigate the cause. On the morning of November 21, the reporter came to the bureau. With the coordination of relevant staff, Xue Feng, director of the Technical Quality Department of the bridge project construction headquarters, accepted an interview.

　　“Overloaded trucks are part of the factor,” Xue Feng explained. They specifically counted the vehicles passing over the bridge: in a 24-hour period, there were nearly 10,000 large trucks leaving the city in one direction alone.

　　According to experts' analysis, Bengbu's sustained high temperatures this year were also a major cause of the bridge deck problems. According to Xue Feng, the Daqing Road Huaihe River Highway Bridge uses an introduced steel box girder structure. A steel box girder, also called a steel plate box girder, is made by splicing steel plates together and looks like a box, hence the name.

　　“The steel box girder has a heat storage function. The sustained high temperatures in Bengbu this year prevented the bridge's heat from dissipating, and it was subjected to prolonged baking.” Xue Feng said that the principle of thermal expansion and contraction caused the steel plates to stretch, and the elongation of the steel plates led to cracking of the road surface, and vehicles driving on it were also prone to forming ruts and small depressions.

　　Afraid of Heat and Cold?

　　Reporter: Since this kind of steel box girder bridge is afraid of heat and cold, why was it designed and introduced?

　　Xue Feng: Steel box girder bridges are relatively popular abroad. Their construction cost is higher than other bridge designs, but the advantage is factory production and relatively light weight.

　　Reporter: Do problems also occur abroad?

　　Xue Feng: Generally not abroad. The problem lies in paving the road surface on the steel plates. All the asphalt and adhesives and other materials are quite special, and we cannot produce them domestically, so they all need to be imported. The asphalt we use is imported from South Korea, and the adhesive is from the UK. However, these countries produce and design these materials according to their own environments, and they cannot adapt to Bengbu's temperatures.

　　Reporter: Since there are difficulties, will this bridge need frequent renovation in the future? What about the maintenance cost?

　　Xue Feng: The repaving is the responsibility of the construction contractor. The bridge has a warranty period of two years. Any problems within two years will be resolved by the contractor, but we do not know the specific cost this time.