出口道短车道对信号控制交叉口通行能力影响

研究出口道短车道在不同交通条件和道路几何条件下对道路交通能力的影响,可以进一步完善交叉口通行能力计算理论体系,对工程设计给出理论依据。介绍了相关研究背景,交叉口出口道短车道对信号控制交叉口通行能力的修正。最后从短车道长度、有效绿灯时间、路段与进口道饱和流量差、交通流基本参数关系模型等因素,分析了出口道短车道对通行能力的影响程度。     

道路路线平纵线形组合设计探讨

阐述了平纵线形组合设计的基本原则,并从排水、交通安全以及节能考虑三方面对平纵线形组合设计提出要求,最后对道路上的常见不良平纵组合类型进行原因探讨,同时提出了相应的改善方法。     

基于加速度干扰的双车道公路服务水平量化研究

服务水平是描述交通流内的运行条件及其驾驶员与乘客感受的一种质量标准。双车道公路服务水平分级采用经验法和模糊综合评判法,缺少强有力的数据说明。在研究双车道公路通行能力时发现,加速度干扰能够较好地反映车辆之间的干扰情况和驾驶员行驶的自由度。运用仿真手段,绘制出饱和度和加速度干扰的关系图,根据该图表现出来的不同车辆运行特征,可以将双车道公路服务水平分为4个等级,并相应给出各级之间跟车率、平均速度的取值范围,从而为通行能力手册修订和公路工程实践提供参考依据。     

山区高速公路线形设计

结合京承高速公路（苇子峪-京冀界段）工程的线形设计,从线形设计方法、平面线形设计、纵面线形设计、平纵线形组合设计和线形与环境的协调五个方面,就如何改进山区高速公路线形设计进行了分析研究,以期指导实践。     

隧道线形设计的安全性分析

通过隧道的平纵线形设计及洞口段平纵组合，对隧道线形设计与行车安全应注意的几个问题进行了分析探讨，指出隧道的平纵面线形与安全问题密切相关，关键是协调好司乘人员的安全意识与线形安全的关系。     

道路平、纵线形组合路段错视觉评价

为了量化评价道路平、纵线形组合路段的驾驶人错视觉,以提高平、纵组合路段驾驶安全水平,提出了用车辆行驶轨迹指标来评价驾驶人错视觉的方法。选择正交试验方法设计道路实验参数,应用仿真软件UC-win/road建立了道路几何参数与驾驶人错视觉之间的仿真模型;利用驾驶仿真模拟完成仿真实验,并进行实验数据的采集与分析;研究了视距、半径、纵坡坡度、缓和曲线长度和转角角度对驾驶人错视觉的影响,并建立了回归方程。从正交试验的极差分析可以看出,道路几何参数与驾驶人的错视觉之间存在较强的相关性,选择合理的道路几何参数对组合路段错视觉的削弱幅度可达10%~50%。对西部某山区高速公路的平、纵组合路段道路几何参数进行评价。分析表明,最容易让驾驶人产生错视觉的路段为不设超高的平曲线路段,从总体来看,凸曲线路段较凹曲线路段更容易让驾驶人产生错视觉。     

山区公路改建工程设计新思路

北京周边郊区大部分山区公路等级为3级或4级。由于建造年代较早,受当时经济条件、技术水平及交通量发展等情况制约,这些道路普遍存在平面线形差、曲线半径过小、视距不良、纵断面坡度大及横断布置较窄等问题。这些问题严重影响了公路行车的安全性和舒适性,通行能力也受到限制。以怀长路(九渡河—桥梓镇)改建工程为例,详细阐述了山区公路线形优化、局部路段经济技术比选、道路与周边环境的融合及沿线自然生态保护等设计细节问题,以期为今后类似的山区公路改建工程设计提供参考和借鉴。     

公路改扩建工程路线设计技术研究

随着社会的发展,我国科技的进步,人民生活水平在不断地提高,其汽车的生产量和运行量也在逐年增加。现如今,我国道路的承受压力越来越大,出现交通混行的现象极为严重,平纵线型指标较低,道路通行能力以及服务水平已经不能满足人们的交通需求、国家发展的需要。我们需要对公路改扩建工程路线进行设计研究,结合国内高速公路改扩建的优秀经验对公路改扩建路线设计原则进行分析,探讨出设计的主要技术问题,保证公路的通行能力和服务能力达到人们的需求。     

公路平曲线与交通安全关系的探讨

平曲线段超高、最小曲线半径等是影响公路平曲线段交通安全的重要因素,在综合探讨该类要素计算取值的基础上,以事故统计数据为基础,对不同道路线形的交通事故数量、严重程度进行分析;印证了平曲线与交通安全关系的重要结论,提出了提升平曲线段交通安全的工程对策。为公路平曲线段的设计、施工提供参考。     

公路线形设计对道路交通安全的影响

详细分析了公路线形设计对道路交通安全的影响,从平曲线、竖曲线和线形组合三方面进行了讨论研究,给出了相关设计标准,并结合实际工程,分析了如何进行公路线形的设计,以满足道路交通安全的设计需求。     

谈高速公路桥涵养护管理

道路桥涵是高速公路的重要组成部分,其承载能力和通行能力是高速公路安全畅通的关键。尤其像邢临高速公路这种桥涵较多的高速公路,必须加强对桥涵构造物的检査和保养,要保证公路畅通无阻,使其保持完好的技术状态,人为的延长其使用年限。特别是近年来,面临养护人员少、车辆超载严重、道路承载能力有限等诸多现实问题,道路和桥梁养护及维修显得尤为重要。     

True Optimization of Pavement Maintenance Options with What-If Models

Abstract:  A prototypical problem road agencies are faced with is to find the optimal application schedule of maintenance works for a given road section. To solve such problems what-if models such as the road transport investment model (RTIM), the highway economic requirements system (HERS), and the highway development and management tool (HDM-4) are widely used to predict the consequences of different maintenance options. With these models maintenance options to be compared must be exogenously specified by an analyst, and the "optimization" with these routines simply chooses the best among those compared. As there are usually infinite numbers of options, it is impossible to exhaust all of them and only suboptimal optimizers may be found with this approach. The present article proposes the use of gradient search methods with what-if models to find the true optima without requiring exogenously specified alternatives. It demonstrates through a case study the feasibility of the use of the steepest descent method and the conjugate gradient method along with HDM-4 to find the true optimum maintenance options.     

Use of Heading Direction for Recreating the Horizontal Alignment of an Existing Road

This article proposes a new method for fitting the horizontal alignment of a road to a set of (x, y) points. Those points can be obtained from digital imagery or GPS‐data collection. Unlike current methods that represent road alignment through its curvature, the proposed method describes the horizontal alignment as a sequence of headings. An analytic–heuristic approach is introduced. The proposed method produces unique solutions even for complex horizontal alignments. Some examples and a case study are presented. This solution may not be accurate enough for road redesign, but it allows researchers and departments of transportation to obtain accurate geometric features.     

Hazard zoning of trunk highway slope disasters: a case study in northern Shaanxi,China

The fragile natural environment of the northern Shaanxi Province in China is susceptible to ambient conditions. Highway slope disasters and the frequent occurrence of highway hazards that different in type, possible outcomes, and scale by region cause severe adverse effects on the construction and operation of trunk highways in the province. Therefore, conducting hazard zoning of highway slope disasters is essential in order to mitigate and manage highway slope disasters and to analyze the distribution regularities of hazards in northern Shaanxi. In this study, a hazard assessment model based on the principle of disaster-causing factor superposition was established. Five hazard assessment indexes, namely terrain gradient, ravine density, annual average days with precipitation more than 25 mm, geotechnical types, and vegetation coverage, were selected to analyze the types of highway slope disasters and disaster-causing factors. The distribution of assessment indexes and the degree of the highway slope disaster hazard were presented using an assessment model and geographic information system (GIS). The hazard zoning of highway slope disasters in northern Shaanxi is classified into slight, moderate, and severe according to hazard characteristics and trunk highway network distribution. Results show that the hazard zoning of highway slope disasters in northern Shaanxi is consistent with the actual distribution.     

Prescreening and Repairing in a Genetic Algorithm for Highway Alignment Optimization

Abstract:   The method of handling infeasible solutions in an evolutionary search algorithm [e.g., genetic algorithms (GAs)] is crucial to the effectiveness of the solution search process. This problem arises because solution search steps, techniques, and operators used in GAs (such as reproduction, mutation, and recombination) are normally  " blind " to the constraints, and thus GAs can generate solutions that do not satisfy the requirements of the problems. In GA-based highway alignment optimization (HAO), many infeasible solutions, which violate model constraints, are also possibly generated, and evaluation of such solutions is wasteful. This study focuses on ways to avoid wasting computation time on evaluating infeasible solutions generated from the GA-based HAO, and develops a prescreening and repairing (P&R) method for an efficient search of highway alignments. The key idea of the P&R method is to repair (before the very detailed alignment evaluation) any candidate alignments whose violations of design constraints can be fixed with reasonable modifications. However, infeasible alignments whose violations of constraints are too severe to repair are discarded (prescreened) before any detailed evaluation procedure is applied. The proposed P&R method is simple, but significantly improves computation time and solution quality in the GA-based HAO process. Such improvements are demonstrated with a test example for a real road project. Through the example study, it is shown that the model incorporating the P&R method can find a good solution much faster (by approximately 23%) than the model with the conventional penalty method. In addition, the P&R method allows the model to evaluate about 70% more solutions than that it can evaluate with the penalty method for the same number of generations.     

对回收路面基层材料的再利用

通过对回收路面基层材料物理力学指标检测,明确了回收路面基层材料再利用的理论依据;通过对同收路面基层材料以及水泥回收沥青路面基层材料的基本性质进行系统的室内试验研究,确定了其对各级公路基层和底基层件能指标的满足情况;综合考虑确定回收路面基层材料在再生混合料中最佳掺配合比,提出合理的施工工艺,并进行经济效益、社会效益分析,为回收路面基层材料的大面积推广利用提供参考.     

Assessment of the neighborhood environmental effects of highway improvements through micronetwork simulation

New Cut Road is a major arterial highway serving South Louisville. Until recently, it was a narrow two‐lane highway of rural‐type design carrying up to 14,000 vehicles per day under forced flow conditions. Then construction began to widen the road from Southside Drive to Old Third Street Road, as a result of Urban Corridor Demonstration Program funding. The impacts (traffic, noise, and air pollution) on the neighborhoods surrounding this widening have been measured through micronetwork simulation techniques. Traffic will be diverted from surrounding roads (up to 20 percent) to the widened New Cut facility, thereby eliminating “over‐capacity” conditions in these facilities, adding several years’ life. Further, expeditious movement of vehicles through the New Cut Road “area of influence” will have a beneficial, albeit small, effect on the local air and noise environment. New Cut Road will be a highly cost‐effective, low‐capital‐intensive improvement.     

基于优化 DEA 模型对公路养护投资决策的有效性研究

为制定科学有效的养护决策,基于高速公路路面性能数据进行神经网络模拟预测了未来 5 个运营年限的路面性能,提出一种新的路面养护决策优化数据包络分析（DEA）模型。该模型以养护里程量、交通量和养护投入资金为输入指标,以路面使用性能恢复值为输出指标,对所提出的 13 种养护方案进行有效性评价,选出投入少、产出高的高效率方案。结果表明:综合考虑交通量、投入资金、产出效率和养护工作量等因素能够客观地筛选出高效率的养护方案。方案结果可为公路管理者做出合理养护决策提供有效依据。     

A proposed weathering classification for basalts and their engineering properties (Turkey)

Most of the volcanic rocks widespread in Turkey are basalt. The effect of weathering processes on the physical and mechanical properties of this type of rock is important. To assess these properties and relations to each other, a study was undertaken in the Niksar region. A detailed investigation was carried out on basalts in the road cuttings of the Niksar ring road and Ünye-Akku?-Niksar highway alignments. A new classification system for basaltic rocks which are substantially influenced by weathering is proposed. The basic engineering properties of the basalt representing each weathering grade were determined. The properties tested are dry density, porosity, coefficient of permeability, uniaxial compressive strength, tensile strength and Young’s modulus. Interrelationships were determined for all test results. It is concluded that there is a substantial degradation in the engineering properties of the rock beyond a specific degree of weathering.     

Preliminary Highway Design with Genetic Algorithms and Geographic Information Systems

A method that integrates geographic information systems (GIS) with genetic algorithms (GAs) for optimizing horizontal highway alignments between two given end points is presented in this article. The proposed approach can be used to optimize alignments in highly irregular geographic spaces. The resulting alignments are smooth and satisfy minimum-radius constraints, as required by highway design standards. The objective function in the proposed model considers land-acquisition cost, environmental impacts such as wetlands and flood plains, length-dependent costs (which are proportional to the alignment length), and user costs. A numerical example based on a real map is employed to demonstrate application of the proposed model to the preliminary design of horizontal alignments.