基于自然驾驶数据的跟车场景潜在风险评估

为弥补传统风险评价指标对相对速度较小的跟车场景危险水平评价能力的不足,减少跟车场景中追尾事故的发生,提出了跟车场景潜在风险的概念。将假定前车以较大制动减速度减速条件下的风险称为潜在风险,并构建了代表驾驶人在潜在危险跟车场景下进行避撞操作需满足的最大反应时间的参数时间裕度（TM）。由于追尾危险工况中常见采取的避撞操作可分为制动和制动转向两大类,分别对典型制动避撞过程和制动转向避撞过程进行了分析,从而推导出分别针对2种跟车潜在危险场景的TM计算方式。通过自动筛选与人工筛选结合,获得了中国自然驾驶数据库（China-FOT）中具有中国驾驶人特点的制动避撞危险工况87个和转向制动避撞危险工况40个进行分级,并基于图像处理方法提取了前车制动开始时刻的TM值,从而得到跟车场景潜在风险两级危险域的划分。结果表明：制动避撞场景下,本车车速过低和过高时,TM值的变化均不明显;而在制动转向避撞场景中,只有速度较高时阈值才保持不变。通过对正常驾驶视频的分析,引入对比组共计正常跟车制动工况163例和正常跟车转向变道工况151例的车头时距（THW）值,其统计分析结果与支持向量机分类结果均难以清晰描述跟车场景危险水平与本车速度之间的关系。为研究跟车场景潜在风险评价在自动驾驶中的应用,对于制动避撞场景,在设定TM值不变和相对速度不变的条件下,分别对基于TM的最小相对距离和距离碰撞时间（TTC）值进行了仿真,仿真结果显示,相比于TTC而言,TM的评价稳定性受相对速度影响小,在自动驾驶跟车策略开发和避免其发生责任追尾事故中有重要应用价值。     

Assessment of port economic impacts on regional economy with a case study on the Port of Lisbon

This article presents a method of assessing the economic impacts of ports at both regional level and national level, through application of input–output analysis. To this end, a methodology for data collection is proposed, which combines a top-down with a bottom-up approach which should help in surpassing some of the difficulties commonly faced in port economic impact studies. The presented methodology allows port planners and policymakers to assess the economic significance and geographic reach of port investments. This study considers the economic impacts of the port cluster and the socio-economic significance of port user industries. The several layers of the analysis are kept separate to allow a better grasp of direct and indirect impacts. The proposed methodology is demonstrated in a study of the Port of Lisbon, which confirms the significance of this port to the Portuguese economy, and also demonstrates that the influence of the Port of Lisbon is mostly limited to an area in close proximity to the port. Therefore, results suggest that investments for the development of logistic infrastructures associated with the port should concentrate in the immediate hinterland of the port.     

Patchwork in an interconnected world: the challenges of transport networks in Sub-Saharan Africa*

Sub-Saharan Africa has recently undergone, or still do in many countries, a period of transport infrastructure expansion. Current policies are centred on the development of international links, which require large capital-intensive projects and are sometimes economically dubious. This paper reviews the past policies and transport functions since colonial times by placing them in their economic and political context. We find that present strategies have similarities to the ones prevailing in previous periods, where expansion phases dominated by transport-led economic growth theories were followed by a stagnation of Africa’s infrastructure development. In view of the challenges in translating findings from empirical research into right policies, we identify the potential of more balanced and sustainable strategic investments, notably by reinforcing the existing secondary transport networks converging into urban centres.     

The changing role of decision support instruments in integrated infrastructure planning: lessons from the Sustainability Check

This article draws lessons about recent innovations in decision support for coping with challenges in integrated infrastructure planning strategies. After setting up a conceptual framework for the scope of analysis and the use of information in infrastructure planning, the empirical section explores the introduction of early-stage sustainability assessment tools. Data collection draws on experiences gained in the Netherlands with a new tool: ‘Sustainability Check’. We conclude that such instruments have a number of capacities that address the challenges of area-oriented planning: (a) bringing together information about the comprehensive value of alternatives, (b) facilitating the generation of alternatives, (c) addressing institutional fragmentation by learning about referential frames, and (d) adding contextual perspectives to the ‘hard’ outcomes of conventional tools. We also conclude that tools such as Sustainability Check should not be seen as a replacement for conventional decision support tools, but rather as complementary to them.     

集装箱货运仿真模型在珠三角港港口投资方案评估(英文)

In the Pearl River Delta (PRD), there is severe competition between container ports, particularly those in Hong Kong, Shenzhen, and Guangzhou, for collecting international maritime container cargo. In addition, the second phase of the Nansha terminal in Guangzhou’s port and the first phase of the Da Chang Bay container terminal in Shenzhen opened last year. Under these circumstances, there is an increasing need to quantitatively measure the impact these infrastructure investments have on regional cargo flows. The analysis should include the effects of container terminal construction, berth deepening, and access road construction. The authors have been developing a model for international cargo simulation (MICS) which can simulate the movement of cargo. The volume of origin-destination (OD) container cargo in the East Asian region was used as an input, in order to evaluate the effects of international freight transportation policies. This paper focuses on the PRD area and, by incorporating a more detailed network, evaluates the impact of several infrastructure investment projects on freight movement.     

The regulatory function in public-private partnerships for the provision of transport infrastructure

A wide range of contractual arrangements are increasingly being used by the public sector to materialise the delegation of transport infrastructure provision tasks to the private sector, over long periods of time. This paper addresses the issue of transport infrastructure regulation in the specific context of public-private settings. Starting by the discussion on the concept of Public-Private Partnership (PPP) it is stressed that, despite the different meanings that can be found in the literature, it is possible to define a PPP by using a core group of characteristics, such as the bundling of services and the transference of a relevant part of the risks to the private sector on a long term basis. Regarding the action of the regulator, we look at three dimensions of efficiency that are expected to be pursued at the strategic level of regulatory action. However, it is acknowledged that the regulatory function is in practice rather complex since it requires balancing a multiplicity of other objectives or goals, which may vary according to specific economic conditions. In the domain of pricing, the review carried out suggests that since “first best” assumptions are not met in the “real world” it hardly seems possible that the short run marginal cost pricing “canon” could be directly used to shape pricing policies. Consequently, when considering the application of the standard neoclassical marginal cost pricing approach it is pertinent to ask whether the second best solutions can lead to efficient outcomes that might be accepted by the stakeholders. Bundling construction and maintenance tasks into a single long term contract, which is a typical characteristic of “standard” PPPs, could theoretically bring cost benefits since it allows for the possible internalization of any positive externalities that may be generated during the whole project life cycle. The economic rationale for the bundling of construction/maintenance with financing services is that it enhances the likelihood of submission of realistic bids at the procurement stage. In addition, the chances of the contractor sticking to the agreed contractual terms, after contract award, are potentially increased given the higher exposure to financial risk.     

The cost of second best pricing and the value of risk premium

Private provision of public infrastructure (PPP) is meant to give incentives to increased efficiency in construction as well in operation and maintenance of the infrastructure e.g. within the transport sector. Efficiency is not only (private) economic efficiency, but also social efficiency e.g. social marginal cost pricing of use of the infrastructure.Is it possible to design contracts concerning payment mechanisms and financial instruments for transport infrastructure that will stimulate social efficiency and optimal allocation of risks between parties? The paper discusses whether different targets can be met and whether compromises may lead to acceptable second best solutions.PPP implies an opportunity to let the user-payment give desired incentives in the form of Social Marginal Cost Pricing (SMCP). A PPP project is a set of contracts and agreements between several parties, including the Government, the private contractor, subcontractors, banks and infrastructure users. These contracts should be designed to give the right incentives to the parties to achieve optimal risk allocation and utilising of resources.Long contract-periods are a common feature of PPPs. The paper examines the way that financial solutions should be designed to achieve the goals for the PPP-projects concerning economic and social efficiency. The expected size and variation of the income stream from the project will influence the loan conditions offered by banks concerning interest rates, guarantees and repayment and also the ability to attract investors. The balance between equity and loans again influences the conditions of the loans. An additional problem is asymmetric information between parties. The private contractor usually knows more about the task than the Government (hidden knowledge), and the Government cannot have full knowledge of the efforts of the contractor (hidden actions).     

交通基础设施 BIM 全景展示平台应用

随着交通基础设施建设数量的逐渐增多和水平的不断提高,国内交通基础设施项目建设现代化、信息化、工业化的方向已成为未来的主旋律和行业转型升级的必然选择。为实现交通基础设施行业数字化应用的拓展和推广,基于对交通基础设施项目汇报和交流核心需求的详细分析,构建BIM全景展示平台,全方位展现项目方案特点及要点,增强对项目方案的理解,降低沟通成本;以实际项目为案例,全面系统说明BIM全景展示平台的应用及达到的效果。     

灾后公路交通基础设施功能快速恢复研究

灾后交通基础设施功能快速恢复，对于提高多样化军事任务军交运输保障能力有着重要意义。从加强抢修抢建的技术保障、计划组织和应急交通保障中新技术、新材料的研制与应用三个方面，阐述了提高灾后公路交通基础设施功能快速恢复的措施，有助于提高灾后公路交通基础设施功能恢复的时效性。     

地铁Ultralight单程票安全解决方案研究

由于价格等因素,国内部分城市地铁自动售票系统选用Mifare Ultralight卡作为单程车票票卡.Ultralight为存储卡,无安全机制,存在容易伪造的隐患.结合实际工作提出了一种单程票安全保障机制,并给出了实现方法.该方法基于PKI(公共密钥基础设施)专用装置实现交易密钥的传输、保存和交易密钥计算,能够有效地防止密钥被破译,且交易密钥能实现安全迅速地更换.