浅谈辽宁省国家高速公路网命名和编号标志改造特点

按照GB5768-2009和国家高速公路网命名和编号规则,将辽宁省高速公路网进行统一命名和编号,重点描述了高速公路出口预告系列标志及指路标志、命名编号标志等的改造特点。     

Biofuel refinery location and supply chain planning under traffic congestion

This research focuses on planning biofuel refinery locations where the total system cost for refinery investment, feedstock and product transportation and public travel is minimized. Shipment routing of both feedstock and product in the biofuel supply chain and the resulting traffic congestion impact are incorporated into the model to decide optimal locations of biofuel refineries. A Lagrangian relaxation based heuristic algorithm is introduced to obtain near-optimum feasible solutions efficiently. To further improve optimality, a branch-and-bound framework (with linear programming relaxation and Lagrangian relaxation bounding procedures) is developed. Numerical experiments with several testing examples demonstrate that the proposed algorithms solve the problem effectively. An empirical Illinois case study and a series of sensitivity analyses are conducted to show the effects of highway congestion on refinery location design and total system costs.     

Evidence of convective instability in congested traffic flow: A systematic empirical and theoretical investigation

An extended open system such as traffic flow is said to be convectively unstable if perturbations of the stationary state grow but propagate in only one direction, so they eventually leave the system. By means of data analysis, simulations, and analytical calculations, we give evidence that this concept is relevant for instabilities of congested traffic flow. We analyze detector data from several hundred traffic jams and propose estimates for the linear growth rate, the wavelength, the propagation velocity, and the severity of the associated bottleneck that can be evaluated semi-automatically. Scatter plots of these quantities reveal systematic dependencies. On the theoretical side, we derive, for a wide class of microscopic and macroscopic traffic models, analytical criteria for convective and absolute linear instabilities. Based on the relative positions of the stability limits in the fundamental diagram, we divide these models into five stability classes which uniquely determine the set of possible elementary spatiotemporal patterns in open systems with a bottleneck. Only two classes, both dominated by convective instabilities, are compatible with observations. By means of approximate solutions of convectively unstable systems with sustained localized noise, we show that the observed spatiotemporal phenomena can also be described analytically. The parameters of the analytical expressions can be inferred from observations, and also (analytically) derived from the model equations.     

Freeway traffic oscillations: Microscopic analysis of formations and propagations using Wavelet Transform

In this paper we identify the origins of stop-and-go (or slow-and-go) driving and measure microscopic features of their propagations by analyzing vehicle trajectories via Wavelet Transform. Based on 53 oscillation cases analyzed, we find that oscillations can be originated by either lane-changing maneuvers (LCMs) or car-following (CF) behavior. LCMs were predominantly responsible for oscillation formations in the absence of considerable horizontal or vertical curves, whereas oscillations formed spontaneously near roadside work on an uphill segment. Regardless of the trigger, the features of oscillation propagations were similar in terms of propagation speed, oscillation duration, and amplitude. All observed cases initially exhibited a precursor phase, in which slow-and-go motions were localized. Some of them eventually transitioned into a well-developed phase, in which oscillations propagated upstream in queue. LCMs were primarily responsible for the transition, although some transitions occurred without LCMs. Our findings also suggest that an oscillation has a regressive effect on car-following behavior: a deceleration wave of an oscillation affects a timid driver (characterized by larger response time and/or minimum spacing) to become less timid and an aggressive driver less aggressive, although this change may be short-lived. An extended framework of Newell’s CF model is able to describe the regressive effect with two additional parameters with reasonable accuracy, as verified using vehicle trajectory data.     

Autonomous vehicle control systems for safe crossroads

This article presents a cooperative manoeuvre among three dual mode cars – vehicles equipped with sensors and actuators, and that can be driven either manually or autonomously. One vehicle is driven autonomously and the other two are driven manually. The main objective is to test two decision algorithms for priority conflict resolution at intersections so that a vehicle autonomously driven can take their own decision about crossing an intersection mingling with manually driven cars without the need for infrastructure modifications. To do this, the system needs the position, speeds, and turning intentions of the rest of the cars involved in the manoeuvre. This information is acquired via communications, but other methods are also viable, such as artificial vision. The idea of the experiments was to adjust the speed of the manually driven vehicles to force a situation where all three vehicles arrive at an intersection at the same time.     

钱江盾构隧道设计速度标准及交通安全分析

通过对6车道钱江盾构隧道工程的通行能力与服务水平、隧道建设与运营养护成本、超大直径盾构机械制造可行性及施工可靠性等方面的综合分析,确定了钱江隧道80 km/h的设计速度标准;通过对内侧3.5 m车道宽度、不设紧急停车带和检修道等横断面设计带来的交通安全风险的分析,提出了相应的交通安全对策,得出了钱江过江通道采用15 m直径盾构隧道的可行性结论。     

兰州市安宁区交通组织优化探讨

文章基于兰州市安宁区交通组织现状,分析了安宁区在道路、交叉口及道路规划方面所存在的主要问题,并从宏观交通、区域交通和微观交通角度出发,探讨了安宁区交通组织优化措施。     

通渭路黄河大桥交通影响评价

文章基于现阶段兰州市道路、桥梁交通量情况,对拟建的通渭路黄河大桥设计方案进行了交通影响评价,并探讨了项目建成后可能存在的问题及相应的解决措施。     

我国北极通航瓶颈问题分析

随着全球气温变暖趋势的显现,北极通航问题日益受到各方面的关注但是要实施北极通航,必须对可能面,临的困难和问题有清楚的认识文中从法律法规、环境保护、船舶和航行奈件,以及船员培训和认证等方面,对中国实施北极通航可能存在的一些瓶颈问题作了初步分析,可为从事北极通航问题研究人员提供参考     

单坡型桥梁混凝土护栏裂纹防撞性能影响分析

由于混凝土材料抗拉强度低的特点,单坡型桥梁钢筋混凝土护栏通常是带裂纹工作的。为了研究裂纹对于单坡型桥梁钢筋混凝土护栏防撞性能的影响,总结了单坡型桥梁钢筋混凝土护栏裂纹特点,并进一步分析了单坡型桥梁钢筋混凝土护栏裂纹的类型。在此基础上,本文采用文献资料调研、理论分析以及计算机仿真方法分析了单坡型桥梁钢筋混凝土护栏裂纹对其防护能力的影响,认为虽然混凝土材料在裂纹处不连续,但由于钢筋的存在,不会影响护栏作为纵向的连续结构整体发挥安全防护作用,因此裂纹对单坡型桥梁钢筋混凝土护栏的防护能力没有影响。本文最终通过实车碰撞试验对分析结果进行了验证。