交叉口左转与直行车辆动态碰撞风险估计模型

为改善交叉口安全状况,提高整个交叉口的交通安全水平,对交叉口碰撞类型之一的左转与直行车辆动态碰撞风险估计模型及警告阈值进行了研究。分析了交叉口左转与直行车辆的运行过程并基于风险内涵,提出了左转与直行车辆的动态碰撞风险估计模型;运用Vissim微观交通仿真软件仿真输出的车辆运行数据计算碰撞风险估计值。仿真结果表明,根据碰撞风险估计值变化规律可以确定出左转与直行车辆的碰撞预警阈值。     

基于VISSIM仿真的交叉口合流放行相位可行性分析

在提出交叉口信号控制合流放行相位可行性问题和介绍微观交通仿真软件VISSIM系统功能的基础上,利用VISSIM软件对不同周期不同流量条件下的交叉口合流放行状态进行仿真,结果表明当出口车道数目与同时放行的左转和直行车道数目之和相同或大于时,合流放行相位在理论上具备一定的可行性。     

Performance evaluation of the inside intersection median-turn lane markings on the mobility and safety performance of signalized intersections in the Philippines and Japan

Signalized intersections are one of the key elements that play a vital role at road networks. The efficiency and safety levels of intersections can affect the operational performance of the whole system. In general, turning traffic, especially median-turning, has always been considered as the most problematic movement in the operation of intersections. This becomes more critical with high turning demand where exclusive turning lanes (single or double) can be assigned to provide larger capacities for these movements and to reduce conflicts with through traffic. However, improper treatment of median-turn lanes could create cross-maneuvering behavior which may limit the expected increase in capacity and create safety issues. Median-turning lane markings are commonly provided at intersections in Japan to guide drivers while turning which is expected to reduce the conflicts among turning traffic. Meanwhile, in the Philippines, exclusive median-turn lanes are installed at intersections without proper treatment which may contribute to the low mobility and safety levels. Therefore, this study evaluated the impact of inside intersection lane markings on the operation of median-turn lanes in terms of mobility and safety. The vehicle maneuver, speed and interactions between the turning traffic were utilized as essential components for the assessment. The empirical analysis shows that conflicting trajectories were present on double turn lanes without median-turn lane markings in the Philippines, which resulted to serious conflicts among the turning vehicles and negatively influenced the turning speed and saturation flow rate of the turn lanes. On the other hand, the turn lane markings in Japan, provided a positive impact to mobility and safety of the turning lanes. Moreover, it was also found that the geometric characteristics and traffic signal phasing scheme highly affects the capacity and safety condition of signalized intersections.     

浅析城市快速发展新形势下的市政道路与排水设计

针对天津市城市化速度急剧加快,而规划、现有市政工程和设施却相对滞后的问题,该文以天津市津涞公路的拓宽改造为例,介绍了目前城市化公路改造设计中,在道路横断面、纵断面、路口、雨污水设计方面存在的不足,提出了初步解决方案和思路.     

基于COONS曲面的平交口立面设计及其程序设计探讨

该文对目前Coons曲面已广泛运用于飞机的机身、机翼、螺旋桨以及汽车、船舶的外形计算机辅助设计作了叙述。接着提出,如果能将交叉口拟合成曲面,由方程确定曲面这一特性,即可用计算机来辅助交叉口立面设计。     

信号交叉口车辆拖延行为分析

在分析HCM2000 Back of Queue模型计算值偏大的原因中,提出了信号交叉口车辆拖延行为的概念,分析了拖延行为导致Back of Queue模型偏大的2种情况。建立了车辆拖延行为3阶段模型,重点推导了拖延行为模型中,低匀速行驶的时间与不发生拖延行为的正常状况下的停车等待时间之间的关系。根据统计分析,确定低匀速行驶的速度和时间的取值范围,在此基础上推导出车辆发生拖延行为的最大时间间隔Tmax,以及车辆发生拖延行为的条件。讨论了Tmax在考虑拖延行为的排队模型中的应用,是对考虑拖延行为的Back of Queue模型研究的进一步深化。     

交叉口视距的三维模型研究

AASHTO和我国城市道路设计规范CJJ37-90推荐的交叉口视距公式所采用的模型为简单的平面交叉（假设为水平相交），而在实际工程设计中存在一些线形特征较为复杂的平纵线形组合的交叉口，若直接运用规范中的视距检验公式进行安全审核将产生很大误差。为解决这一问题，建立了交叉口的三维模型：主要道路上有平纵线形组合、次要道路具有纵坡、交叉角为任意角度，并在相应的视线坐标系下确定了左右向来车的平面坐标。通过对道路表面和道路外建筑进行视线检验，确保驾驶者视线不被道路表面的任一点以及道路外建筑物所阻碍。该模型的应用面较原先的广泛，可对具有复杂线形特征的交叉路口的视距情况进行检验，从而评价道路本身及路口建筑物对行车安全视距的影响，提高交叉口范围内的行车安全保证：     

基于Ecotect的T型交叉路口布灯方式仿真分析

为研究灯具布置对T型交叉口的照明影响,通过采用照明仿真软件对T型交叉口的交错式、对称式及中心对称式3种布灯方案进行仿真模拟分析,得到了不同布灯方式下的照明强度。结果表明:在相同灯具及条件下,交错式布灯方案最优,但道路终端灯光光强设置需偏大;对称式方案效果次之,交叉口中心位置照度低;中心对称式集中照明效果最好,但相比交错式及对称试其经济能耗最大。通过照明仿真模拟分析,有效验证了交错式布灯方案在T型交叉口照明设计中的优越性。     

Application of social force model to pedestrian behavior analysis at signalized crosswalk

Limited pedestrian behavior models shed light on the case at signalized crosswalk, where pedestrian behavior is characterized by group or individual evasion with surrounding pedestrians, collision avoidance with conflicting vehicles, and response to signal control and crosswalk boundary. This study fills this gap by developing a microscopic simulation model for pedestrian behavior analysis at signalized intersection. The social force theory has been employed and adjusted for this purpose. The parameters, including measurable and non-measurable ones, are either directly estimated based on observed dataset or indirectly derived by maximum likelihood estimation. Last, the model performance was confirmed in light of individual trajectory comparison between estimation and observation, passing position distribution at several cross-sections, collision avoidance behavior with conflicting vehicles, and lane-formation phenomenon. The simulation results also concluded that the model enables to visually represent pedestrian crossing behavior as in the real world.     

交叉口无干扰条件下右转机动车轨迹建模

利用视频提取技术,对不同几何条件交叉口的右转车辆数据进行采集,并利用Track pro软件获得车辆位置坐标,计算车辆平均运行轨迹;然后分别用对数函数和二次多项式对轨迹进行拟合,通过比较拟合结果,确定右转机动车轨迹模型为对数函数模型;同时通过分析交叉口转角、出口道位置、车辆速度等轨迹影响因素与轨迹参数之间的关系,对模型参数进行了标定;最后选择工程实例,利用实测数据对模型进行了验证。结果表明,利用模型计算的轨迹坐标点与实际值的最小相对误差为0.34%,验证了模型的有效性。