城市公交车微环境对乘客舒适度的非线性影响

Nonlinear effects of bus micro-environments on passengers’comfort

公交车是服务居民日常活动—出行的重要微观空间,也是城市公共空间的组成部分。目前,车厢内微环境污染及其对乘客的负面效应已引起广泛关注。然而,国内外鲜少有研究分析公交车微环境对乘客舒适度的非线性影响,也尚未探测各个微环境变量影响舒适度的阈值以及乘客的最佳微环境暴露水平。论文在广州6条典型公交线路上同时收集车内微环境实时监测数据、乘客问卷调查数据、公交出行属性数据和公交车外部环境,采用随机森林算法构建公交车微环境与乘客舒适度之间的非线性模型并展开分析。研究表明,公交车内温度、相对湿度、PM2.5浓度、噪声和载客量均对舒适度有非线性影响,但影响程度各不相同。当车内温度为23.5~28.0℃、相对湿度为45%~58%、PM2.5浓度<28μg/m3、噪声<75 dB、载客量为8~26人时,有助于乘客在车厢微环境中拥有良好的舒适度水平。论文研究结果与现行环境标准存在一定差异,相关研究结论对城市微观空间规划与治理、微环境标准制定和交通管理有显著的政策启示和实践意义。

Buses play an important role in the daily travel of urban residents.Bus micro-environmental pollution and its adverse impacts on passengers’physical and psychological well-being has become an increasing concern among the general public,researchers,and policymakers.However,few studies have examined the nonlinear effects of bus micro-environments on passengers’comfort,analyzed the threshold values of multiple microenvironmental variables,and ascertained the optimal micro-environmental exposure levels for passengers.In this study,real-time monitoring data of bus micro-environments,questionnaire survey data of 520 passengers,travel characteristics,and environments outside the buses were simultaneously collected on six bus routes in Guangzhou City.Nonlinear regression models constructed by random forest were then employed to explore the relationships between bus micro-environments and passengers’comfort.The results show that in-bus temperature,relative humidity,PM2.5 concentrations,noise,and passenger load have nonlinear effects on the comfort,but the importance and mechanism of each micro-environmental variable in influencing comfort is different.Passengers have a higher degree of comfort when in-bus temperature is 23.5-28.0℃,relative humidity is 45%-58%,PM2.5 concentrations are lower than 28μg/m3,noise level is lower than 75 dB,and passenger load is 8-26 persons.Also,there are some differences between the optimal micro-environmental exposure levels identified in this study and current environmental standards.These findings have theoretical and practical implications for policymakers,transportation planners,and bus operators when improving bus microenvironments and promoting passengers’comfort.