2004, after a five-year debate on whether to use steel-on-steel rail track, or maglev technology. Maglev was not chosen due to its incompatibility with China's existing rail-and-track technology and its high price, which is two times higher than that of conventional rail technology. Technology debate Although engineers originally said construction could take until 2015, the China's Ministry of Railways initially promised a 2010, opening date for the new line. However, the Ministry did not anticipate an ensuing debate over the possible use of maglev technology. Although more traditional steel-on-steel rail technology was chosen for the railway, the technology debate resulted in a substantial delay of the railway's feasibility studies, completed in March 2006. The current rolling stock is the CRH380AL, which is a Chinese electric high-speed train that was developed by China South Locomotive & Rolling Stock Corporation Limited (CSR). CRH380A is one of the four Chinese train series which have been designed for the new standard operating speed of on newly constructed Chinese high-speed main lines. The other three are CRH380B, CRH380C and CRH380D. Engineering challenges Testing began shortly thereafter on the main line section between Shanghai and Nanjing. This section of the line sits on the soft soil of the Yangtze Delta, providing engineers an example of the more difficult challenges they would face in later construction. In addition to these challenges, high speed trains use extensive amounts of aluminium alloy, with specially designed windscreen glass capable of withstanding avian impacts. Construction Construction work began on April 18, 2008. Track-laying was started on July 19, 2010, and completed on November 15, 2010. On December 3, 2010, a 16-car CRH380AL trainset set a speed record of on the Zaozhuang West to Bengbu section of the line during a test run. On January 10, 2011, another 16-car modified CRH380BL train set a speed record of during a test run. The overhead catenary work was completed on February 4, 2011 for the entire line. According to CCTV, more than 130,000 construction workers and engineers were at work at the peak of the construction phase. According to the Ministry of Railways, construction has used twice as much concrete as the Three Gorges dam, and 120 times the amount of steel in the Beijing National Stadium. There are 244 bridges and 22 tunnels built to standardized designs, and the route is monitored by 321 seismic, 167 windspeed and 50 rainfall sensors. Start of