城轨车辆车控制动系统和架控制动系统防滑控制对比分析

为比较城轨车辆车控制动系统和架控制动系统在防滑控制方面的差异,详细分析车控制动系统和架控制动系统的防滑控制原理.从系统构成、控制软件、参考速度准确性和安全完整性等级等4方面,比较车控制动系统和架控制动系统的防滑控制功能,分析车控制动系统防滑安全功能安全完整性等级比架控制动系统高的原因.     

快速公交系统通行能力计算方法研究

快速公交系统的通行能力是由瓶颈车站决定的.首先分析了车站通行能力的基本原理和主要影响因素,并基于排队论构造了单一停靠位通行能力的计算模型.同时,根据北京、杭州和昆明三地快速公交系统(公交专用道)的实际运营状况对模型参数进行了详细地标定和说明,提出缩短公交车平均停靠时间和改善系统运营稳定性是提升通行能力的重要途径.在此基础上,以北京市南中轴路快速公交为例,说明了模型的应用方法,并定量分析了各种因素对通行能力的影响.最后,对多停靠位车站的周转效率变化规律进行了分析,提出了其通行能力的计算方法.     

重庆轨道交通白居寺车辆段段内发车能力研究

重庆轨道交通2号线是我国第一条跨座式单轨线路,2004年运营至今客流急剧增加,现状客流已达到远期设计客流,正线运营行车间隔已缩短至3 min,从而对车辆段的出段能力提出了更高的要求.车辆段出段能力的主控制因素是段内发车能力,对白居寺车辆段段内发车能力的研究不仅能提升该车辆段的出段能力,而且对提升2号线的运营效率和降低运...     

城市轨道交通应急管理体系研究

城市轨道交通建设快速发展,线网化的地铁运营向城市轨道交通应急管理提出了更高的要求,本文在充分调研广州地铁应急管理的基础上,从应急组织管理、应急预案管理、应急资源管理以及突发事件管理4个方面论述建立科学轨道交通应急管理体系的方法.     

Dynamic stochastic transit assignment with explicit seat allocation model

This paper proposes a stochastic dynamic transit assignment model with an explicit seat allocation process. The model is applicable to a general transit network. A seat allocation model is proposed to estimate the probability of a passenger waiting at a station or on-board to get a seat. The explicit seating model allows a better differentiation of in-vehicle discomfort experienced by sitting and standing passengers. The paper proposes simulation procedures for calculating the sitting probability of each type of passengers. A heuristic solution algorithm for finding an equilibrium solution of the proposed model is developed and tested. The numerical tests show significant influences of the seat allocation model on equilibrium departure time and route choices of passengers. The proposed model is also applied to evaluate the effects of an advanced public transport information system (APTIS) on travellers’ decision-making.     

Environmental life-cycle assessment of transit buses with alternative fuel technology

The paper presents a life-cycle assessment of costs and greenhouse gas emissions for transit buses deploying a hybrid input-output model to compare ultra-low sulfur diesel to hybrid diesel-electric, compressed natural gas, and hydrogen fuel-cell. We estimate the costs of emissions reductions from alternative fuel vehicles over the life cycle and examine the sensitivity of the results to changes in fuel prices, passenger demand, and to technological characteristics influencing performance and emissions. We find that the alternative fuel buses reduce operating costs and emissions, but increase life-cycle costs. The infrastructure requirement to deploy and operate alternative fuel buses is critical in the comparison of life-cycle emissions. Additionally, efficient bus choice is sensitive to passenger demand, but only moderately sensitive to technological characteristics, and that the relative efficiency of compressed natural gas buses is more sensitive to changes in fuel prices than that of the other bus types.     

城轨交通信号系统资源共享与互联互通

实现城市轨道交通信号系统资源共享的基本形式有技术共享、操作界面和方式的共享、检修设备共享、人力资源共享、维修工艺共享、仿真培训设备资源共享等;信号系统互联互通的基本条件是:信号制式相同,系统结构和功能划分一致,地车信息传输系统兼容,列车定位技术兼容或统一,ATP安全控制方式统一设计和要求,列车驾驶模式和操作方式统一,信号与车辆接口相同,信号与PIS系统合理分配频道和接口;实现信号系统互联互通的基本手段有:采用同一厂商相同制式的信号系统,加装多套信号车载设备和地面设备.采用通用的信号车载设备,实现规范和标准的信号互联互通等.概括介绍国外轨道交通资源共享与互联互通的研究发展情况.     

Adaptive control algorithm to provide bus priority with a pre-signal

In urban areas, where road space is limited, it is important to provide efficient public and private transportation systems to maximize person throughput, for example from a signalized intersection. To this end, this research looks at providing bus priority using a dedicated bus lane which is terminated upstream of the intersection, and placing an additional signal at this location, called a pre-signal. Although pre-signals are already implemented in some countries (e.g. UK, Denmark, and Switzerland), an adaptive control algorithm which responds to varying traffic demands has not yet been proposed and analyzed in the literature. This research aims to fill that gap by developing an adaptive control algorithm for pre-signals tailored to real-time private and public transportation demands. The necessary infrastructure to operate an adaptive pre-signal is established, and guidelines for implementation are provided. The relevant parameters regarding the boundary conditions for the adaptive algorithm are first determined, and then quantified for a typical case using a micro-simulation model. It is demonstrated with case studies that, under all considered scenarios, implementing a pre-signal with the proposed adaptive control algorithm will result in the least average person delay at the intersection. The algorithm is expected to function well with a wide range of car demands, bus frequencies, and bus passenger occupancies. Moreover, the algorithm is robust to errors in these input values, so exact information is not required.     

Time-based life-cycle assessment for environmental policymaking: Greenhouse gas reduction goals and public transit

As decision-makers increasingly embrace life-cycle assessment (LCA) and target transportation services for regional environmental goals, it becomes imperative that outcomes from changes to transportation infrastructure systems are accurately estimated. Greenhouse gas (GHG) reduction policies have created interest in better understanding how public transit systems reduce emissions. Yet the use of average emission factors (e.g., grams CO₂e per distance traveled) persists as the state-of-the-art masking the variations in emissions across time, and confounding the ability to accurately estimate the environmental effects from changes to transit infrastructure and travel behavior. An LCA is developed of the Expo light rail line and a competing car trip (in Los Angeles, California) that includes vehicle, infrastructure, and energy production processes, in addition to propulsion. When results are normalized per passenger kilometer traveled (PKT), life-cycle processes increase energy use and GHG emissions up to 83%, and up to 690% for smog and respiratory impact potentials. However, the use of a time-independent PKT normalization obfuscates a decision-maker’s ability to understand whether the deployment of a transit system reduces emissions below a future year policy target (e.g., 80% of 1990 emissions by 2050). The year-by-year marginal effects of the decision to deploy the Expo line are developed including reductions in automobile travel. The time-based marginal results provide clearer explanations for how environmental effects in a region change and the critical life-cycle processes that should be targeted to achieve policy targets. It shows when environmental impacts payback and how much reduction is achieved by a policy-specified future year.     

Factors influencing the choice of shared bicycles and shared electric bikes in Beijing

China leads the world in both public bikeshare and private electric bike (e-bike) growth. Current trajectories indicate the viability of deploying large-scale shared e-bike (e-bikeshare) systems in China. We employ a stated preference survey and multinomial logit to model the factors influencing the choice to switch from an existing transportation mode to bikeshare or e-bikeshare in Beijing. Demand is influenced by distinct sets of factors: the bikeshare choice is most sensitive to measures of effort and comfort while the e-bikeshare choice is more sensitive to user heterogeneities. Bikeshare demand is strongly negatively impacted by trip distance, temperature, precipitation, and poor air quality. User demographics however do not factor strongly on the bikeshare choice, indicating the mode will draw users from across the social spectrum. The e-bikeshare choice is much more tolerant of trip distance, high temperatures and poor air quality, though precipitation is also a highly negative factor. User demographics do play a significant role in e-bikeshare demand. Analysis of impact to the existing transportation system finds that both bikeshare and e-bikeshare will tend to draw users away from the “unsheltered modes”, walk, bike, and e-bike. Although it is unclear if shared bikes are an attractive “first-and-last-mile solution”, it is clear that e-bikeshare is attractive as a bus replacement.