Correlation Study Of Multiple Environmental Factors In Changchun Metro Carriages

As the urban population grows and expands,the metro,as a convenient,fast and large capacity transportation,has become the first choice for people to commute.However,due to the relatively closed space of metro carriage and high crowding rate,the indoor environmental quality of the carriage will directly affect the health and comfort of passengers.Therefore,the effective improvement of the indoor environmental quality of metro carriages has become a critical issue that has garnered significant attention from society.In order to effectively improve environmental quality,it is necessary to accurately test and scientifically assess the correlation between multiple objective environmental factors in the carriages and passengers’subjective satisfaction,and to determine how these factors can be improved to improve passenger satisfaction.In this study,the indoor environmental quality of Changchun Metro Line 1 and 2 carriages was analyzed and studied in December 2021 using on-site field measurements and questionnaire research,and a total of 1059 valid samples were obtained.This study firstly tested the thermal,air,light and acoustic environments of the carriages and compared the measured values with the codes to determine whether they met the code requirements.Secondly,a seven-level satisfaction scale（including very dissatisfied,dissatisfied,less satisfied,moderate,more satisfied,satisfied and very satisfied）was used to judge passengers’satisfaction with the metro carrriage environment,and the questionnaire was used to obtain passengers’perceived responses to the current environment to explore the reasons for dissatisfaction.Then,the measured environmental parameters were fitted with passenger satisfaction to analyze the effect of individual environmental parameters on passenger satisfaction.Finally,the overall passenger satisfaction prediction model was developed based on multiple linear regression and BP neural network.The main conclusions of this study are as follows.（1）The temperature,relative humidity,air velocity,PM_2.5 concentration,CO₂concentration,formaldehyde concentration,illumination and A sound level of Changchun Metro carriages in winter all meet the requirements of the code.（2）The results of the questionnaire survey show that passengers’satisfaction and acceptance of the acoustic environment are the lowest,and the correlation between satisfaction with the acoustic environment and overall satisfaction is high,which indicates that the improvement of the carriage acoustic environment needs to be paid attention to.（3）According to the linear regression model of passengers’average thermal sensation voting value and temperature,the neutral temperature of Changchun Metro carriage is 19.18℃,which is much lower than the average measured carriage temperature（24.2℃）,so from the perspective of energy saving and passengers’comfort,it is suggested that the carriage temperature can be appropriately reduced by about 5℃.（4）In this study,the evaluation model of indoor environmental quality of metro carriages in severe cold areas was established based on multiple linear regression and BP neural network classification regression,and the prediction effect and accuracy of the two models were compared by paired t-test,and the results showed that the overall passenger satisfaction model constructed based on BP neural network theory was optimal.The indoor environmental quality satisfaction evaluation model of metro carriages established in this paper lays the foundation for creating a healthy and comfortable indoor environment of the carriages,provides reference for the design and operation decisions of metro carriages,and is beneficial to strengthening the enhancement and management of the indoor environmental quality of the carriages,thus contributing to the healthy and sustainable development of urban rail transportation.