soil and structure impact in real-time so that immediate response could be taken to any disruption. In the same section, secondary grouting and a micro-pile cut-off wall was used to reinforce the tunnels. In addition, a floating track bed was used for the tracks crossing these areas to reduce vibrations. Continental Engineering Corporation constructed the underground stations and the tunnels in this section. Five shield tunneling sections totaling and of cut-and-cover sections were excavated. Arrival areas near the MRT departure areas were constructed. Tunneling under the Tamsui River The section passing below Tamsui River (about in length) employed the shield-tunneling method. The double-O-tube (DOT) shield tunnel machine was used for the first time in Taiwan. The -long tunnels took 1 year to dig, and were completed in December 2010. Chingshan Road section This section was built along a steep roadside slope. Traditional construction methods would greatly increase the difficulty, cost, and excavation area necessary to build an elevated line through the area. In order to reduce environmental impact and cut construction time, a bamboo-cut treatment was used in construction to keep the slope intact. Top ring girders in diameter were used to gradually excavate the area, after which a diameter foundation can be placed. A total of 15 bamboo-cut foundations were constructed, ranging from a height of 5.88 to 16.35 meters. By June 2010, the contractor (Fu Tsu Corporation) had completed 13 of the 15 bases, with the additional two under construction. Trial operations Trial operations between Taipei and Huanbei began on 2 February 2017. 1.4 million passengers used the system during this period, double the expected 700,000 passengers. Route extension and future stations Zhongli railway station extension In December 2008, the MOTC announced that the system would be extended to Zhongli Sports Park , but was later changed to Zhongli Station in order to facilitate transfers to TRA services. After the Zhongli Sports Park station was canceled, MOTC changed it to having the Taoyuan Metro Green Line to run to Zhongli Sports park instead, and to have the Green Line extend to Zhongli Station. The extension includes one entirely new station, , scheduled to open in July 2023. The full extension to Zhongli is scheduled for completion in 2028. A 2011 report by the Council for Economic Planning and Development estimated the total project cost at NT$13.801 billion, including the extension as well as development of the surrounding areas.