基于PCA和ICA的交通流量数据压缩方法比较研究

针对交通流量数据的特点,分别采用基于主成份分析(PCA)和独立成份分析(ICA)的方法对其进行数据压缩研究和比较。首先,对城市道路和高速公路的交通流统计特性进行分析:发现采样时间的大小不会影响研究结果,而流量离差的统计分布为接近高斯分布的超高斯分布。然后分别采用基于PCA和ICA的方法进行交通流数据的压缩与重构,并对结果进行全面比较。试验结果表明:由于城市道路和高速公路的交通流离差数据均接近高斯分布,因此PCA在数据压缩中的效果较好;而高速公路的交通流数据压缩结果优于城市道路,因为其更加规律和稳定。这一结果反映了交通流波动的随机特征,对于进一步的交通流分析有着重要的意义。     

Transport Demand Management in Turkey: A Genetic Algorithm Approach

Abstract

This article proposes new models for estimating transport demand using a genetic algorithm (GA) approach. Based on population, gross national product and number of vehicles, four forms of the genetic algorithm transport planning (GATP) model are developed – one exponential and the others taking quadratic forms – and applied to Turkey. The best fit models in terms of minimum total average relative errors in the test period are selected for future estimation. Demand management strategies are proposed based on three scenarios: restricting private car use, restricting truck use and the simultaneous management of private car use and goods movement. Results show that the GATP model may be used to estimate transport demand in terms of passenger-kilometers traveled (pass-km), vehicle-kilometers traveled (veh-km) and ton-kilometers completed (ton-km). Results also show that the third scenario – simultaneous restrictions on private car use and goods movement – could reduce total veh-km by about 35% by 2025 in this study of Turkish rural roads.     

南京市快速公交系统（BRT）的规划和建设

南京积极推进公交优先发展战略的实施,优化交通结构,提高公交对市民出行的吸引力。本文介绍了BRT的组成与基本元素,从中国城市的实际出发,阐述了“优先发展公共交通”、“绿色交通”的理念,提出了公交体系建设的基本要求,介绍了BRT在省内城市常州、连云港的应用,针对南京快速公交现状与需求,提出BRT建设和管理的建议。     

浅谈公共交通公众出行信息服务系统的应用

本文阐述了公众出行信息服务系统在公共交通领域中的应用,目标是建设个性化的公交实时位置信息接入平台,用户可以通过自己的手机,随时随地查询本市各公交车辆的实时位置、上下行方向等信息,方便市民适时安排自己的乘车计划,达到方便出行的目的.     

Freight Transport Deceleration: Its Possible Contribution to the Decarbonisation of Logistics

The paper challenges the conventional view that the movement of goods through supply chains must continue to accelerate. The compression of freight transit times has been one of the most enduring logistics trends but may not be compatible with governmental climate change policies to cut greenhouse gas emissions by 60–80% by 2050. Opportunities for cutting CO₂ emissions by ‘despeeding' are explored within a freight decarbonisation framework and split into three categories: direct, indirect and consequential. Discussion of the direct carbon savings focuses on the trucking and deep-sea container sectors, where there is clear evidence that slower operation cuts cost, energy and emissions and can be accommodated within current supply chain requirements. Indirect emission reductions could accrue from more localised sourcing and a relaxation of just-in-time (JIT) replenishment. Acceleration of logistical activities other than transport could offset increases in freight transit times, allowing the overall carbon intensity of supply chains to reduce with minimal loss of performance. Consequential deceleration results from other decarbonisation initiatives such as freight modal split and a shift to lower carbon fuels. Having reviewed evidence drawn from a broad range of sources, the paper concludes that freight deceleration is a promising decarbonisation option, but raises a number of important issues that will require new empirical research.     

银西线庆阳至西安段建设方案研究

银西线是宁夏、蒙西地区南下陕西及中东部经济发达地区的快捷通道,功能定位为一条客货兼顾的大能力区际快速干线铁路,本线在庆阳至西安段与西平线位于同一通道内,在建西平线是一条以煤运为主、兼顾地方客货运输的单线铁路。考虑本线与西平铁路可相互承担货运任务,从通道整体运量水平来看,初期双线输能基本饱和,近期三线输能基本饱和,远期需形成四线规模,故两线存在共线运行或通道实行客货分线运输的可能。根据现阶段铁路建设思路和技术政策,对本线及局域路网进行深入的对比分析,结合对铁路网络整体格局、通道运输需求及输送能力适应性、运输质量、投资效益等因素的综合比较,选择合理建设方案。     

公交可达性水平分析方法在城市静态交通规划中的应用

近年来我国大城市机动车保有量增长迅速,城市交通面临严峻考验,动静态交通之问的矛盾以及“停车难”等问题日益突出,但一直以来静态交通规划均以满足停车需求为主,缺乏考虑与公共交通等方面的联系.本文对公交可达性水平分析方法在城市静态交通规划中的应用进行了具体介绍,该方法将静态交通和动态交通、公共交通和个体交通、交通设施和交通管...     

对城乡公交一体化体系框架的研究

在城乡一元化发展的时代背景下,文章首先从运输方式和研究内容上,对城乡公交一体化的体系框架进行了介绍,并结合我国客运发展的实际水平,提出在城市与乡镇之间应采取严格的公交运营方案;在乡镇与行政村之问亦采取公交化的运营策略.在此基础上,从区域、城区、乡镇、行政村4个层面,对城乡公交一体化应重点解决的问题进行了深入分析,并形成...     

Measuring the welfare effects of infrastructure: A simple spatial equilibrium evaluation of Dutch railway proposals

We specify a spatial computable general equilibrium model for the Netherlands based on the so-called New Economic Geography. The model distinguishes 14 sectors, two modes of transportation and over 500 municipalities. Key parameters are estimated by fitting predicted interregional trade flows to bi-regional input-output data. The model is then calibrated to a baseline scenario for 2020. From there, the transport grid is modified in line with six proposals for changes in rail infrastructure. The effects of these changes on employment and welfare are computed. We find that the most ambitious project leads to a redistribution of around 8000 jobs from regions further out to regions along the line and especially at the end of it. The net national welfare effect is equivalent to a 250 million euro (0.016%) increase in GDP.