In 2004, the earliest subway construction exploration and test was carried out in Tangqiao, Pudong. A 4.2-meter-diameter shield was excavated using a reinforced concrete segment lining using the structural method, and more than 100 meters of tunnel was pushed to verify the feasibility of constructing a tunnel in silty sandy soil and silt-mixed clayey soil.
In 1964, near Hengshan Park, subway tunnels and subway station tests were carried out. The subway test project was codenamed "Project 60", and an electric battery was used in the subway, which was completely confidential at that time. The size of the station is only 80 meters * 20 meters * 20 meters, and the scale is built according to the stop of the 3-meter-deep, wide-section train formation, and the construction technology is the deep well method. When connected to Hengshan Road, two 600-meter-long tunnels were dug and the whole project was called the Shanghai Underground Railway Expansion Pilot Project. Due to the small size and depth of the station and the underground tunnel, it was not integrated into the construction of Line 1, but laid the foundation for the subsequent construction of the subway. As of 2014, the facility still remains underground in Hengshan Park.
At the end of the 70s, under the ground of Caoxi Park, the second test tunnel was tried, with an investment of more than 40 million yuan and a total length of 1,290 meters. The structural method used to construct a continuous concrete wall (square tunnel) on this section of the line is significantly different from the shield tunneling (circular tunnel) that was used later. This section of the line is used as the official route of Shanghai Rail Transit Line 1.
