水资源开发Conflict问题调整的META-game解析法

多元化的资源开发间Conflict问题的协调与消除始终是关系开发计划能否实施的重要课题,作为META—game理论的Conflict问题的数理解析方法是Conflict解析法.本文将以多目的水资源开发所涉及Conflict问题为研究对象,利用META-game理论的Conflict数理解析方法对问题进行安定分析,寻求问题的答案,即均衡解.最终提出Conflict问题消除的、能被矛盾各方接受的比较方案,供决策部门选择.     

Estimation of left-turning vehicle maneuvers for the assessment of pedestrian safety at intersections

Improving pedestrian safety at intersections remains a critical issue. Although several types of safety countermeasures, such as reforming intersection layouts, have been implemented, methods have not yet been established to quantitatively evaluate the effects of these countermeasures before installation. One of the main issues in pedestrian safety is conflicts with turning vehicles. This study aims to develop an integrated model to represent the variations in the maneuvers of left-turners (left-hand traffic) at signalized intersections that dynamically considers the vehicle reaction to intersection geometry and crossing pedestrians. The proposed method consists of four empirically developed stochastic sub-models, including a path model, free-flow speed profile model, lag/gap acceptance model, and stopping/clearing speed profile model. Since safety assessment is the main objective driving the development of the proposed model, this study uses post-encroachment time (PET) and vehicle speed at the crosswalk as validation parameters. Preliminary validation results obtained by Monte Carlo simulation show that the proposed integrated model can realistically represent the variations in vehicle maneuvers as well as the distribution of PET and vehicle speeds at the crosswalk.     

The Role of Universities in Supporting Integrated Coastal Management in the United Kingdom

Integrated coastal management has been seen as the way to deal with the challenges currently facing managers of our coastal zones. In the tropics, these areas are typified with resources such as coral reefs and mangroves that are able to support a variety of activities. Integrated coastal management takes a multi-disciplinary approach that involves the integration of the different institutions and stakeholder groups in the coastal zone. A survey of tropical coastal locations revealed that fully implemented integrated coastal management is limited with programs apparently failing at the implementation stage. These coastal zones share a number of common challenges exacerbated by poverty and conflicts between the coastal activities. Conflict management needs to be incorporated into the management process that pays particular attention to the overextraction of resources and destructive resource use.     

Traffic Impact Analysis of the Access to Projects on Traffic Performance of Nearby Roadways

Access to any development is a connection between the buildings and urban roadways. The impact of access on urban roads varies with location of the access. This paper studies the impact of access to large buildings on the surrounding road network by exploring traffic conflicts based on the configuration of the access. The concept of conflict intensity is introduced in this study as a new evaluation indicator to evaluate the traffic conflict triggered by the presence of access. The results show that the greater the speed, the greater the conflict intensity of access. Meanwhile, a similar situation exists when other variables (e.g., conflict angle or the number of conflicts) change. The larger the conflict intensity, the more dangerous the access. Results from this study can help developers and traffic engineers choose suitable locations of access and organize the traffic in a logical manner.     

A constraint programming model with time uncertainty for cooperative flight departures

The lack of a proper integration of strategic Air Traffic Management decision support tools with tactical Air Traffic Control interventions usually generates a negative impact on the Reference Business Trajectory adherence, and in consequence affects the potential of the Trajectory-Based Operations framework. In this paper, a new mechanism relaying on Reference Business Trajectories as a source of data to reduce the amount of Air Traffic Controller interventions at the tactical level while preserving Air Traffic Flow Management planned operations is presented. Artificial Intelligence can enable Constraint Programming as it is a powerful paradigm for solving complex, combinatorial search problems. The proposed methodology takes advantage of Constraint Programming and fosters adherence of Airspace User’s trajectory preferences by identifying tight interdependencies between trajectories and introducing a new mechanism to improve the aircraft separation at concurrence events considering time uncertainty. The underlying philosophy is to capitalize present degrees of freedom between layered Air Traffic Management planning tools, when sequencing departures at the airports by considering the benefits of small time stamp changes in the assigned Calculated Take-Off Time departures and to enhance Trajectory-Based Operations concepts.     

北京市平面交叉口弱势群体安全改善措施

非机动车及行人在交通事故中占很大比例,并处于弱势地位,急需得到特殊保护。利用交通冲突技术（TrafficConflictTechnique,TCT）分析行人和非机动车在交叉口的安全状况,提出减少冲突的策略。以北京市交通冲突问题较典型的平面交叉口为例,针对设置非机动车二次左转待转线、为右转机动车设置右转红绿灯、为行人设置二次过街安全岛、改变平面交叉口护栏长度及位置等典型改善措施,采用违章比例、车速、步速、冲突数等指标,对比分析措施实施前后交叉口的交通运行状况,评价改善措施实施效果。结果表明,采取的改善措施能提高平面交叉口弱势群体的交通安全性。     

公路平面交叉口驾驶行为研究

面对目前公路平面交叉口交通事故严重的现状,为了公路平面交叉口交通事故致因分析和加深对交叉口驾驶行为的了解程度,探讨了公路平面交叉口驾驶行为理论,总结了目前道路交通系统交通事故原因及其导致事故所占比例,分析了交叉口交通系统,给出了影响交叉口驾驶行为的具体因素。在驾驶行为三阶段基础上,研究了交叉口驾驶行为模型,分析了交叉口驾驶行为特征和交叉口驾驶行为与交通事故发生的一般关系。并针对驾驶失误和不安全驾驶行为给出了防止措施,以减少交叉口交通事故。     

Modelling shared space users via rule-based social force model

The promotion of space sharing in order to raise the quality of community living and safety of street surroundings is increasingly accepted feature of modern urban design. In this context, the development of a shared space simulation tool is essential in helping determine whether particular shared space schemes are suitable alternatives to traditional street layouts. A simulation tool that enables urban designers to visualise pedestrians and cars trajectories, extract flow and density relation in a new shared space design, achieve solutions for optimal design features before implementation, and help getting the design closer to the system optimal. This paper presents a three-layered microscopic mathematical model which is capable of representing the behaviour of pedestrians and vehicles in shared space layouts and it is implemented in a traffic simulation tool. The top layer calculates route maps based on static obstacles in the environment. It plans the shortest path towards agents’ respective destinations by generating one or more intermediate targets. In the second layer, the Social Force Model (SFM) is modified and extended for mixed traffic to produce feasible trajectories. Since car movements are not as flexible as pedestrian movements, velocity angle constraints are included for cars. The conflicts described in the third layer are resolved by rule-based constraints for shared space users. An optimisation algorithm is applied to determine the interaction parameters of the force-based model for shared space users using empirical data. This new three-layer microscopic model can be used to simulate shared space environments and assess, for example, new street designs.     

Operating cost sensitivity to required time of arrival commands to ensure separation in optimal aircraft 4D trajectories

Trajectory optimisation has shown good potential to reduce environmental impact in aviation. However, a recurring problem is the loss in airspace capacity that fuel optimal procedures pose, usually overcome with speed, altitude or heading advisories that lead to more costly trajectories. This paper aims at the quantification in terms of fuel and time consumption of implementing suboptimal trajectories in a 4D trajectory context that use required times of arrival at specific navigation fixes. A case study is presented by simulating conflicting Airbus A320 departures from two major airports in Catalonia. It is shown how requiring an aircraft to arrive at a waypoint early or late leads to increased fuel burn. In addition, the efficiency of such methods to resolve air traffic conflicts is studied in terms of both fuel burn and resulting aircraft separations. Finally, various scenarios are studied reflecting various airline preferences with regards to cost and fuel burn, as well as different route and conflict geometries for a broader scope of study.