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261.
Xumei Chen Lei Yu Yushi Zhang Jifu Guo 《Transportation Research Part A: Policy and Practice》2009,43(8):722-734
Improving the reliability of bus service has the potential to increase the attractiveness of public transit to current and prospective riders. An understanding of service reliability is necessary to develop strategies that help transit agencies provide better services. However, few studies have been conducted analyzing bus reliability in the metropolis of China. This paper presents an in-depth analysis of service reliability based on bus operational characteristics in Beijing. Three performance parameters, punctuality index based on routes (PIR), deviation index based on stops (DIS), and evenness index based on stops (EIS), are proposed for the evaluation of bus service reliability. Reliability involves routes, stops, punctuality, deviation, and evenness. The relationship among the three parameters is discussed using a numerical example. Subsequently, through a sampling survey of bus lines in Beijing, service reliability at the stop, route, and network levels are estimated. The effects of route length, headway, the distance from the stop to the origin terminal, and the use of exclusive bus lanes are also analyzed. The results indicate low service reliability for buses in Beijing and a high correlation between service reliability and route length, headway, distance from the stop to the origin terminal, and the provision of exclusive bus lanes. 相似文献
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263.
Bi Yu Chen William H.K. Lam Agachai SumaleeQingquan Li Zhi-Chun Li 《Transportation Research Part A: Policy and Practice》2012,46(3):501-516
To assess the vulnerability of congested road networks, the commonly used full network scan approach is to evaluate all possible scenarios of link closure using a form of traffic assignment. This approach can be computationally burdensome and may not be viable for identifying the most critical links in large-scale networks. In this study, an “impact area” vulnerability analysis approach is proposed to evaluate the consequences of a link closure within its impact area instead of the whole network. The proposed approach can significantly reduce the search space for determining the most critical links in large-scale networks. In addition, a new vulnerability index is introduced to examine properly the consequences of a link closure. The effects of demand uncertainty and heterogeneous travellers’ risk-taking behaviour are explicitly considered. Numerical results for two different road networks show that in practice the proposed approach is more efficient than traditional full scan approach for identifying the same set of critical links. Numerical results also demonstrate that both stochastic demand and travellers’ risk-taking behaviour have significant impacts on network vulnerability analysis, especially under high network congestion and large demand variations. Ignoring their impacts can underestimate the consequences of link closures and misidentify the most critical links. 相似文献
264.
太原轨道交通前期项目信息化管理系统的构建 总被引:1,自引:0,他引:1
文章旨在针对太原轨道交通前期项目全过程监控、综合管理信息库构建、资料文件建档查询、数据统计分析,以及管理层决策的项目管理和决策支持系统进行了论述。信息管理系统根据实际需求梳理工作流程,并在流程中嵌入管理子系统,以实现工作流程和项目全过程的信息化、标准化、规范化管理,形成一个结构合理、数据共享、严谨高效的工作平台,以提高工作效率和管理水平,为轨道交通后续项目报审、工程开工建设提供强有力的技术支撑。 相似文献
265.
文章结合天水过境高速公路路面实体工程,对不同孔隙率条件下的Super-pave-13高性能沥青混合料进行了车辙试验及SPT试验分析。结果表明,要保证Superpave-13沥青混合料具有较好的高温稳定性,其压实孔隙率应控制在4%~6.5%范围内。 相似文献
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267.
文章以沈阳地铁中街站大跨度隧道工程为研究对象,应用FLAC3D计算软件,对复杂条件下浅埋暗挖大跨度隧道引起的地表沉降变形特征进行了数值模拟。根据洞桩法施工开挖方案,紧密结合工程实际,将动态施工开挖过程划分五个工况进行模拟,分析各施工工况对地表变形的影响和分布规律,并按工程信息化施工要求事前将预测数据提供施工单位,以指导施工控制地表沉降。模拟结果表明,采用洞桩法开挖施工过程中,对地层土体扰动较大,明显影响隧道中心附近地表变形的步序是小导洞开挖和初期支护扣拱施工阶段,约占最终沉降量的70%;而其他步序影响较小。最终,地表沉降在隧道横向分布呈"W"形态。模拟结果与现场监测数据具有较好的拟合性,表明利用数值分析方法预测大跨度隧道施工期地表沉降是可靠的。 相似文献
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269.
为实现TBM施工隧道的实时地质预报,以TBM刀盘滚刀破岩震动作为震源的HSP法地质预报技术为基础,通过分析TBM施工工艺与机身结构特点,对HSP系统硬件和软件进行优化设计,使其小型化、自动化和智能化,并搭载于TBM上进行智能控制。在TBM掘进过程中,首先,通过隧道轮廓位置的检波器连续或高频次地采集地震反射波信号; 然后,经系统软件对数据的自动处理,实时获取掌子面前方地层反射特征参数图谱; 其次,通过智能识别技术完成对不良地质反射界面的有效拾取与判识; 最后,实现不良地质的探测。通过对适于TBM施工的HSP法实时预报技术进行优化设计,实时探查前方地层不良地质(体)位置、规模与性质,为TBM的高效施工起到一定的推助作用。 相似文献
270.
Helene Bareksten Solvang Nikolaos Valantasis-Kanellos Dong-Wook Song 《Maritime Policy and Management》2018,45(4):495-513
This qualitative inductive research explores the potential benefits for the Scandinavian economy and ports through the implementation of the Northern Sea Route (NSR) as an alternative for container shipping to the established Southern route through the Suez Canal. To extract expert’s opinions and address these objectives, we utilised in-depth face-to-face semi-structured interviews through purposive sampling in a single case study setting. The analysis of the data demonstrates that the commercialisation of NSR can yield benefits for the Scandinavian economy (e.g. GDP increase, jobs creation) and reveals the benefits of Scandinavian ports (e.g. ECA’s, flexibility, hinterland, etc.) compared to other ports in North West Europe, which potentially grasp the NSR as an opportunity. However, it is highlighted that this can only be achieved if Scandinavian countries are proactive and secure their involvement. 相似文献