Subway simulation of CO2 concentration during close mode operation

Air quality in subways continue to attract the attention of the general public, government and researchers. Air quality is complex and difficult to address due to its integrated relationship with factors such as the outdoor environment, passenger flow, train movement and ventilation modes. Furthermore, at a subway design level, there are few measures or controls in place to ensure the verification of required environmental control systems. This paper selects CO2 concentration as an indicator of air quality within subways and establishes a subway simulation method to predict CO2 concentrations in a subway during close mode operation (CMO). In order to verify the simulation method, a typical subway line was selected for separate field testing of CO2 concentration changes for a station, tunnel and train carriage. The results showed that the calculation model was consistent with the test results. Therefore, this simulation method could be used to analyze CO2 concentrations within subways at the design stage, thereby allowing the development of a viable scheme and operation mode for an environmental control system.