Exploration On Comprehensive Evaluating Method And Indicator System Of Indoor Environmental Quality In Subway Stations

The rapid development of subway systems has facilitated transportation,but the large number of passengers and train operations can lead to a deterioration of the indoor environmental quality in underground subway stations.Therefore,it is urgent to develop a comprehensive evaluation method and index system for the indoor environmental quality of subway stations.Currently,subjective perception evaluation using questionnaires or evaluation based on measured data and reference values of indicators are the main methods used.However,most studies only focus on a single aspect of environmental quality,resulting in one-sided and less comprehensive evaluation results that may deviate significantly from the actual situation and fail to provide effective improvement suggestions for station management.In this study,we first conducted separate analyses of the effects of various factors such as temperature and humidity,noise,lighting,and air quality on the indoor environmental quality of subway stations.We then established a three-level comprehensive evaluation index system consisting of objective,criteria,and solution layers.We used the Analytic Hierarchy Process（AHP）and subjective weighting method to determine the subjective weights of evaluation indices at each level and the entropy method combined with measured values to determine their objective weights.The results showed that in the criteria layer,air quality had the highest weight proportion of53.41%,followed by thermal,acoustic,and lighting environment quality,with weight proportions of 30.55%,10.75%,and 5.29%,respectively（both subjective and objective weights had the same weight proportion）.In the solution layer,for subjective factors,odor had the highest weight proportion of 33.08%,followed by air temperature,PM_2.5,equivalent sound level,air velocity,CO₂,glare,relative humidity,and illumination in decreasing order of weight proportion,with illumination uniformity having the lowest weight proportion of 0.72%.For objective factors,CO₂had the highest weight proportion of 43.91%,followed by relative humidity,air velocity,equivalent sound level,air temperature,PM_2.5,odor,illumination,and glare in decreasing order of weight proportion,with illumination uniformity having the lowest weight proportion of 0.72%.We then used the principle of minimum relative entropy to narrow the deviation between subjective and objective weights and obtain more scientifically and reliable comprehensive optimal weights.Finally,the calculated results showed that the optimal comprehensive weights of the evaluation indices for indoor environmental quality of subway stations were ranked in decreasing order as CO₂,air temperature,odor,equivalent sound level,PM_2.5,air velocity,relative humidity,illumination,glare,and illumination uniformity.Finally,by combining the fuzzy comprehensive evaluation method with the optimal weights obtained from the subjective and objective synthesis,a comprehensive evaluation model for the environmental quality inside subway stations is proposed.In this model,the evaluation conclusions in the objective layer,as well as the evaluation language intervals for criteria layer and indicator layer,are divided into five levels:excellent,good,moderate,poor,and very poor.In this study,subjective and objective research examples were selected to apply this method.Taking a certain station on Xi’an Metro Line 5 as a subjective research example,the results showed that both passengers and staff rated the environmental quality as"good."However,the main reasons for not reaching the"excellent"rating were different,with air quality and the overall rating of the acoustic environment being not sufficiently high.For the objective research examples,a certain station on Xi’an Metro Line 2 and another station on Line 1 were chosen.The results indicated that the maximum membership degrees for the fuzzy comprehensive evaluation of their environmental quality were 51.53%and 49.23%,respectively,corresponding to a rating of"good."Furthermore,a comprehensive analysis was conducted using a specific station on Xi’an Metro Line 2 as an example,which revealed that the evaluation of its internal environmental quality did not reach the"excellent"level.The main reason for this was that the overall rating of the acoustic environment inside the subway station was not sufficiently high.