地铁公共区及隧道防排烟系统研究

以北京地铁13号线东直门站为例,结合车站公共区与区间隧道的防排烟系统设置情况,分别采用CFD三维模拟与一维网络模拟的方法,对火灾时烟气的分布及气流流动状况进行预测分析,说明防排烟系统的可靠性对于保证火灾情况下的安全疏散能力至关重要。     

北京地铁 6 号线换乘车站设计特色

北京地铁6号线是北京轨道交通线网中的东西干线,通过对该线换乘车站方案的思路和实践的论述,介绍不同换乘车站方案的研究情况,重点分析如何兼顾以人为本和适应现场条件进行地铁车站设计,从而提出平衡的设计方案,为今后换乘车站的设计提供借鉴。     

时速160 km城市轨道交通内置式泵房板式道床动力特性分析

北京轨道交通新机场线在部分区间隧道的最低点设置了内置式泵房板式道床。为了保证时速160 km市域列车在动荷载作用下轨道结构的安全性和可靠性,建立了车辆-轨道-隧道三维耦合动力分析模型,计算分析100~220 km/h共7种行车速度下内置式泵房板式道床的动力特性。提取道床振动评价指标(垂向位移、垂向加速度)、道床强度评价指标(纵横向拉应力)、行车平稳性评价指标(车体垂向、横向加速度)和行车安全性评价指标(轮轨垂向力、轮轨横向力、脱轨系数、轮重减载率)与规范允许值进行对比。计算结果表明,各动力学评价指标均随行车速度的增大而增加,各动力学评价指标均在规范允许值之内,并且有较大的安全余量。     

时速160 km城市轨道交通双块式轨枕设计

为研究城市轨道交通有挡肩双块轨道结构的稳定性,依托国内首条时速160 km城市轨道交通线路-北京轨道交通新机场线,对有挡肩双块式轨枕进行尺寸设计及配筋设计:(1)结合线路特点,对有挡肩双块式轨枕承轨台抗压能力及挡肩抗剪能力进行检算;(2)为计算桁架钢筋受力情况,通过有限元模型计算起吊、堆载、施工上人3种工况下双块式轨枕的受力情况。计算结果表明,起吊及施工上人荷载对双块式轨枕的受力性能影响不大;堆载对其受力性能有较大的影响,双块式轨枕的堆放层数不应大于6层。     

北京新机场线高架地段双块式无砟轨道结构设计

北京新机场线是我国首条最高速度达160 km/h的地铁线,轨道结构采用双块式无砟轨道,高架地段首次采用取消底座结构设计,为了保证轨道结构的安全可靠,有必要对无砟轨道道床结构进行结构选型及配筋设计。通过建立高架地段无砟轨道结构的有限元模型,对道床板板长、板宽、板厚进行了选型分析。针对无砟轨道无底座设计方案,考虑了列车荷载、温度梯度、桥梁挠曲3种主要荷载类型,提出了荷载组合方案,研究其关键控制因素,对道床板进行了配筋设计及检算。通过参数比选,完成了道床板的尺寸参数选择;在3种荷载类型中,温度梯度在道床板中引起的弯矩值最大,在设计荷载中占据主导因素,合理减小道床截面高度可有效降低温度梯度作用;道床板配筋应以控制裂缝为原则进行设计。     

粘贴钢板补强技术在国贸桥加固中的应用

目前,用于桥梁补强加固的方法主要有碳纤维加固、粘贴钢板加固等。该文介绍了北京国贸桥一期异形板板底加固采用了粘贴钢板补强加固方法。即:采用化学锚栓将钢板锚固于桥面,钢板与桥面间预留缝隙,四周封口后采用高效改性环氧粘接剂灌注填充缝隙。此方法具有较高的强度、刚度、稳定性、整体性和耐久性,可供今后类似工程借鉴。     

北京客运交通枢纽满意度及设计要素调研分析

客运交通枢纽是城市客运系统中的重要组成部分,有效的枢纽设计对提高出行效率具有重要意义。为了对今后枢纽的设计工作提供技术支持,该文针对北京已建的8座枢纽,从枢纽整体运营、换乘大厅、标志设施三个方面开展满意度调研分析。在此基础上,从设计关注要素、换乘设施、采光、商业设施等方面分析了枢纽设计的关键要素,主要研究结果表明:枢纽设计应以实现交通功能为主导,有效减少换乘距离是设计中最需关注的因素。     

The capitalization of subway access in home value: A repeat-rentals model with supply constraints in Beijing

Urban rail transit enhances accessibility of the communities it serves and often contributes to the value of local real properties. A small number of studies have gone beyond the traditional cross-sectional hedonic analysis to use repeat-sales data in the US for more robust estimation of rail transit’s impact on property value. While the empirical literature generally supports the positive capitalization of rail transit in home value, it has produced widely varied estimates and failed to incorporate the theoretical insight that more elastic housing supply would reduce the extent of local amenities’ capitalization in home value. Observing Beijing’s rapid expansion of subway lines during the late 2000s, this study uses repeat rental transactions from 2005 to 2011 to investigate how home value reacts to the change in the home’s distance to nearest subway station. Repeat-rentals estimates suggest a rent-distance elasticity of −0.02, 70% below the cross-sectional hedonic estimate. Moreover, using the unique history of state-owned enterprise relocations as instrument for intra-city variation in land supply, we find that the capitalization of subway proximity in home value is weaker where land supply is more elastic. Our findings support the significant bias caused by omitted variables in the hedonic estimates and confirm housing supply’s role in explaining the intra-city spatial variation in estimates.     

How does air pollution influence cycling behaviour? Evidence from Beijing

It is widely believed air pollution is an obstacle to cycling as it has negative effects on cyclists’ health outcomes and deteriorates their cycling experiences. However, the empirical studies investigating the impact of air pollution on cycling behaviour remains scarce. The aim of this paper is to fill the gap by looking at Beijing as a case study. The authors conducted a survey of 307 cyclists on the days with different levels of air quality in terms of concentration of PM_2.5 in 2015. The results show that in the polluted weather, those who persist in cycling are more likely to be male, over 30 years old, lower income or those who travel short distances. Specifically, female cyclists have a higher tendency to shift from cycling to public transit than the males and medium and high-income earners are more likely to shift to using a car than low income earners. The residents’ subjective perceptions of safety and comfort have major effects on their cycling behaviour. A higher perception of comfort and safety is related to a higher possibility of continuing cycling when air quality became polluted. Cycling for commuting trips is less likely to be replaced by other modes than cycling for non-commuting trips, such as shopping. Results of this study reveal that improving air quality in a metropolitan area such as Beijing has co-benefits of cycling renaissance. The huge investments into cycling infrastructure should be integrated with policies designed to create an attractive environment for cycling.     

北京市定制商务班车乘客支付意愿研究

生活水平的极大提升导致居民对出行品质期望更高,因此对出行疲劳缓解和在途时间有效利用的考虑在交通服务质量改善的研究及措施中愈加不可回避。基于北京市定制商务班车乘客支付意愿调查,首先分析定制商务班车的线路特征和客流特征。其次,对比研究出行者选乘定制商务班车前后服务特性的差距,特别关注长距离出行者对出行疲劳、无效在途时间减少的支付意愿。结果表明,乘客放弃原有出行方式选择定制商务班车与这一服务所带来的体能消耗、无效在途时间节省呈现较高相关性,乘客愿意支付远高于当前公交票价的费用用于上述两方面的改善。最后指出,如能对当前服务模式稍作调整,接受一定比例的非预订座位乘客,高水平公交服务的受众群体将更为广泛。