互通式立交超高设计若干问题探析

超高设计是互通式立交设计中的一项重要内容，其与互通的平面、纵断面均有较大关联性，在匝道的平面线形设计时，无论是否设置超高，只要有曲率变化，均宜采用缓和曲线进行线元连接，以保证匝道超高、加宽的渐变设置，同时应考虑纵坡对超高的影响，现就互通式立交超高设计中存在的若干问题进行探析。     

基于VISSIM仿真的立交桥出口匝道缓和段长度研究

文章分析了出口匝道的事故成因,提出了在变速车道和圆曲线之间增设缓和段的设计方案,并运用VISSIM仿真软件对各种缓和段长度进行仿真评价分析,得出了匝道设计速度为50 km/h时的适宜缓和段长度模型,为其他匝道形式及设计速度的缓和段长度选取提供依据.     

互通式立交匝道分岔尖圆心位置的计算

介绍互通式立体交叉中匝道分岔尖位置的计算方法。     

基于曲率半径的公路超高设计方法

在高等级公路路线设计中,为保证行车舒适性,往往设置较长的缓和曲线以达到平面线形的协调和曲率的舒缓过渡。采用较长的缓和曲线时,超高过渡只在缓和曲线某一区段内进行。目前行业内对全超高断面的选择主要以《公路路线设计规范》为依据,将全超高断面设置于圆缓点(YH)或缓圆点(HY)上。发现该方法可能引起部分过渡路段反超高或超高不足。本文通过研究不同圆曲线半径与横向力系数和超高值的关系,提出基于曲率半径的超高设计方法。计算表明该法可有效弥补常规方法的不足,在运行速度偏高的公路中推荐采用。     

平曲线路段事故数目与线形元素的关系

基于IHSDM的思想，针对我国国道上平曲线路段的线形特点，分析了平曲线路段的线形元素和事故数目之间的函数关系。     

多路互通式立交选型与布设

多路互通式立体交叉的产生有其必然条件,文章在总结三路和四路立交形式的基础上,提出了五路和六路立体交叉的几种可能形式,并重点讨论了多路互通式立交布设时如何选择主线跨越方式、立交出口形式和左转匝道的类型。     

汾阳国道307线赵家庄互通式立体交叉设计

本文以国道307线汾阳过境改线工程中的赵家庄互通为例,阐述了在当前国省道干线升级改造中,设置互通立体交叉的一些实际情况、制约因素,结合实际、因地制宜进行方案比选。以及在互通式立体交叉设计实际工作中,平纵指标、鼻端高程、匝道接坡、与被交路平交、对视距的要求和检验进行探讨,为同类互通式立体交叉提供借鉴。     

浅析独柱墩曲线梁桥抗倾覆加固方法

本文采用有限元分析法对安徽省境内G30连霍高速与G3京台高速交汇处朱圩子互通立交独柱墩曲线梁桥(A匝道、B匝道、G匝道、H匝道)的抗倾覆能力进行验算分析,并结合桥梁结构特点,提出桥梁抗倾覆加固方法,以此提高独柱墩曲线梁桥的抗倾覆稳定性能,进而使得桥梁结构受力更加合理。     

互通式立交纵断面联动设计及三维检验

互通式立体交叉平面、纵断面设计相互制约,当修改某条匝道的纵断面设计时,通常会牵扯到关联的其他匝道,修改极为不便。鉴于此,提出了一套解决方案,能在修改某一匝道纵断面数据后,自动修改关联匝道纵断面的设计数据,在提高工作效率的同时保证了设计的准确性。同时,通过读取平纵数据文件,能在AutoCAD中生成匝道三维曲面,并可通过动态观察器进行多角度动态观察,设计成果一目了然,为设计、复核、演示等提供了有力的保障。     

重庆嘉陵江复线桥主桥箱梁悬臂施工线形控制

文中主要介绍了三向预应力连续刚构的线形的影响因素、控制、实际操作方法以及线形控制采用灰色系统理论预测法的理论模型建立。本桥采用成桥目标曲线和运营目标曲线作为施工过程中的线形控制，此理论在国内类似桥梁施工属首例。     

基于空间统计学的长输管道地质灾害分布模式研究

针对管道沿线的地质灾害分布模式,采用空间统计学中的自相关系数进行研究,并应用该方法评价实际管道地质灾害整体聚集程度,识别局部地质灾害高发聚集区.与传统的管道地质灾害统计分析方法相比,自相关系数基于空间位置进行属性关联关系分析,能够在总体和局部两个层面量化计算地质灾害的空间聚集程度,其计算结果易于排序使用,可以为管道地质...     

Numerical optimal control method for shockwaves reduction at stationary bottlenecks

The paper introduces an optimal control method for traffic management with variable speed limits. It consists of traffic flow dynamics prediction with a non‐linearized Lighthill–Whitham–Richards macroscopic traffic flow model, introduction of a cost functional, which enables stable shockwaves optimization, and numerical implementation of the optimization process with differential evolution. The method overcomes the discretization issues and provides speed limits that are in general not limited to small number of successive discrete points, i.e. variable message signs locations, nor in rounded speed limits. Performance of the method is demonstrated on a case study, which shows promising reduction of the backward moving shockwave that occurs because of a stationary bottleneck. Copyright © 2016 John Wiley & Sons, Ltd.     

An anisotropic continuum model considering bi-directional information impact

In traffic flow with naturalistic driving only, stimulus information pre-dominantly comes from the preceding vehicles with drivers occasionally responding to the following vehicles through the inspection of rear-view mirrors. Such one-sided information propagation may potentially be altered in future connected vehicle environment. This brings new motivations of modeling vehicle dynamics under bi-directional information propagation. In this study, stemming from microscopic bi-directional car-following models, a continuum traffic flow model is put forward that incorporates the bi-directional information impact macroscopically but can still preserve the anisotropic characteristics of traffic flow and avoid non-physical phenomenon such as wrong-way travels. We then analyze the properties of the continuum model and respectively illustrate the condition that guarantees the anisotropy, eradicates the negative travel speed, preserves the traveling waves and keeps the linear stability. Through a series of numerical experiments, it is concluded that (1) under the bi-directional looking context only when the backward weight ratio belongs to an appropriate range then the anisotropic property can be maintained; (2) forward-propagating traffic density waves and standing waves emerge with the increasing consideration ratio for backward information; (3) the more aggressive driving behaviors for the forward direction can delay the backward-propagating and speed up the forward-propagating of traffic density waves; (4) positive holding effect and negative pushing effect of backward looking can also be observed under different backward weight ratios; and (5) traffic flow stability varies with different proportion of backward traffic information contribution and such stability impact is sensitive to the initial traffic density condition. This proposed continuum model may contribute to future development of traffic control and coordination in future connected vehicle environment.     

路基边坡坡面冲刷稳定性的模糊综合评判方法

基于边坡冲刷稳定性有较大的随意性和不确定性,文章利用模糊数学理论,对坡面冲刷进行分级模糊综合评判,为边坡坡面冲刷稳定性综合评价提供了一条新的途径。     

基于BP神经网络的PGIS空车位数预测建模研究

文章采用BP神经网络对城市停车诱导信息系统（PGIS）中的空余车位数进行预测研究,建立了基于BP神经网络的PGIS空车位数预测模型,并介绍了模型预测的过程和方法。     

扶壁式挡墙在工程运用中的探讨

为确保路基及防护的稳定,昭待高速公路11合同段K316＋630-K316＋730跨越深层软基段路基采用了扶壁式挡墙的防护形式。文章结合该工程设计实践,对扶壁式挡墙的力学建模的简化及受力计算、结构验算方法进行了探讨,并对其使用效果及经济性进行了评述。     

输油气管道清管器跟踪定位方法及跟球选址技巧

以提高清管器现场定点跟踪的准确性为目的,提出了清管器模糊定位的数学计算方法,并针对球前后不同介质形式,给出了相应的选址技巧。结合实际应用,结果表明该简易计算方法对清管器的模糊位置判断具有一定的可信度,应用此方法计算的时间要综合考虑管道路由情况,可更加准确地预判清管器到达时间,对现场实际操作人员的工作具有一定的借鉴意义。     

连续箱梁节段预制安装施工技术

文章依托具体工程实例介绍连续箱梁节段预制安装施工方法及原理,详细阐述了架桥机安装施工流程、步骤和方法,分析了预制安装施工的关键技术。     

高速公路建设期重大危险源辨识探讨

文章基于危险源及重大危险源的一般定义,结合湖北杭瑞高速公路建设的实际情况,提出了高速公路建设期重大危险源的定义,并通过建立概率风险评价分析模型,采用事故树分析法和德尔菲法确定了事故发生的概率值,得出了判别重大危险源的风险度临界值,以对类似高速公路建设期重大危险源的辨识提供指导。     

The role of transportation sectors in the Korean national economy: An input-output analysis

The transportation industry has been playing an important role in the economic development of Korea and, thus, has become a critical factor in sustaining the well-being of the Korean people. This paper attempts to analyze the economic impacts of four transportation modes using input-output (I-O) analysis, with specific application to Korea. To this end, we apply the I-O models to the Korean I-O tables generated by the Bank of Korea, paying particular attention to the four transportation sectors in Korea (rail, road, water, and air transportations), considering them as exogenous, and then determining their impacts. Specifically, the production-inducing effects, supply shortage effects, sectoral price effects, forward linkage effects, and backward linkage effects of the four transportation modes are quantitatively derived over the period 2000–2010. For example, the production-inducing effect of a KRW 1.0 production or investment in transportation is larger in the petroleum and transportation equipment sectors than in other sectors. Furthermore, the rail and road transportation sectors have greater supply shortage effects than the other transportation sectors. Finally, the potential uses of the results of this analysis are presented from the perspective of policy instruments, and policy implications are discussed.