Planning and construction inspecting the new trains A metro system in Taichung was discussed since 1990, which would connect various suburbs including
Caotun,
Zhongxing New Village, and others. The plan was dropped due to high cost and low projected ridership. A new proposal was renewed and approved in 2004, but construction did not begin immediately because of costs exceeding estimates and disagreements over where stations would be. In 2010, preliminary work began by relocating trees on the
median and rerouting the utilities that run under those roads. Progress was plagued by various delays, including conflicts between the city and electrical contractors, problems with
land acquisition, and the bankruptcy of a major utilities contractor. Because of the delays, mayor
Jason Hu and his administration were heavily criticized by rivaling political parties. Formal construction began in May 2013. Two separate incidents occurred during construction. On 19 August 2014, a crane malfunctioned and broke off its arm, falling on top of a restaurant. No injuries were reported. Then, on 10 April 2015, a crane's arm snapped while lifting a 209-ton
I-beam, causing the beam to fall and crushing a car underneath. Workers atop the beam were also thrown off. The driver of the car and three workers lost their lives, while four other works sustained heavy injuries. Construction was halted for three months following the incident. On 30 June 2016, construction of the line was completed, and testing began soon after. Initially, the stations numbers were numbered sequentially from G1 to G20, with the "G" representing green. However, since G8 is pronounced similar to
chi-bai, which is considered
profane in Hokkien, the "G" prefix was changed to "1", which represents how the Green line is the first line completed. The station's English names were initially written in a mix of
Tongyong Pinyin and
Hanyu Pinyin, and the lack of standardization drew criticism. On 24 August 2020, the Taichung City Council decided to use Hanyu Pinyin for all stations except for
Sihwei Elementary School.
Operations Beginning on 16 November 2020, the Green line was opened to the public for testing and was free to ride until its formal opening ceremony planned for on 19 December. On the first day, 70,977 passengers used the line. However, on 21 November, the
couplers on one of the trains snapped in half; the line was closed to the public the next day. Trial runs resumed on 25 March 2021. An opening ceremony was held on 25 April 2021. ==Rolling stock==