Study on the Integration of Underground Public Spaces and Rail Transit in Old City Center

In order to explore the coupling and coordination relationship between underground public spaces and rail transit in the old city center, the principles of coupling and coordination forced from physics are applied to analyze the integration of underground public spaces and rail transit in the city center. A coupling evaluation model and indicator system are constructed from four aspects: scale, form, intensity and equilibrium. Taking into account the phased characteristics of the integrated system in Xinjiekou central area, four time points, namely 2005, 2010, 2014, and 2019, are selected to calculate the coupling degree, which are 0.8308, 0.8963, 0.9351, and 0.8921, respectively. The coupling degree decreased in 2019, while the coupling coordination degree showed an increasing trend of 0.482, 0.5556, 0.6504, and 0.676, respectively. The reason for this trend is that although the early development of rail transit has driven the exploration of the scale and environmental quality of underground public spaces, the improvement of indicators such as the scale and form of the urban rail transit network falls short in the short term, limiting the level of integrated development. Based on this, optimization strategies for the integration of underground public spaces and rail transit in the Xinjiekou central area are proposed.