Durability of Bridge Expansion Joints with Perforated Dowels Under Traffic Impact Loading

In design phases, expansion joints are required to have movement capacity, bearing capacity for static and dynamic loading, watertight, low noise emission and traffic safety. On the basis of the fact that failure due to dynamic loading is the main reason for the observed damages, attention is focused on the bearing capacity for dynamic loading governed by impact, because it differs from the static loading. In this study, from the viewpoint of durability, experimental studies for dynamic behavior were conducted for aluminium alloy expansion joints with perforated dowels. The validity of the perforated dowels against traffic impact loading was confirmed by both experimental and numerical studies.

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.

Traffic Impact on Incentive Contracting Project Time Performance during Highway Construction

The volume of highway traffic in the United States continues to increase. In the face of this there is a concomitant need to improve and repair transportation infrastructure. Construction frequently requires a reduction in capacity during construction activity; consequently road users as well as adjacent businesses must endure the delays and inconveniences associated with transportation construction. Recognizing the problems that construction can produce, state highway agencies （SHAs） have continually sought ways to minimize the negative impact from their construction operations. Incentive contracting has played an important role in this effort to improve project performance. The Florida Department of Transportation （FDOT） is one of the leading SHAs using such innovative contracting methods as Incentive/Disincentive （I/D）, A＋B （cost plus time bidding） combined with I/D, No Excuse Bonus, and Liquidated Savings. This paper analyzes the traffic impact on incentive project time performance using highway construction projects recently completed in Florida. Project data obtained from FDOT were evaluated using time performance indices. A survey of traffic impact on project work types was performed in Florida in order to evaluate the relationship between construction project types and road traffic influence during construction. Based on the survey results, the 38 most frequently used work types in Florida during the study period were categorized into three traffic impact levels： （1） high traffic impact, （2） medium traffic impact, and （3） low traffic impact. Statistical analysis was performed. The results show that there are significant differences on project time performance between low and high impact levels as well as low and medium impact levels.

Traffic Impacts on Fine Particulate Matter Air Pollution at the Urban Project Scale: A Quantitative Assessment

Formal health impact assessment (HIA), currently underused in the United States, is a relatively new process for assisting decision-makers in non-health sectors by estimating the expected public health impacts of policy and planning decisions. In this paper we quantify the expected air quality impacts of increased traffic due to a proposed new university campus extension in Chapel Hill, North Carolina. In so doing, we build the evidence base for quantitative HIA in the United States and develop an improved approach for forecasting traffic effects on exposure to ambient fine particulate matter (PM2.5) in air. Very few previous US HIAs have quantified health impacts and instead have relied on stakeholder intuition to decide whether effects will be positive, negative, or neutral. Our method uses an air dispersion model known as CAL3QHCR to predict changes in exposure to airborne, traffic-related PM2.5 that could occur due to the proposed new campus development. We employ CAL3QHCR in a new way to better represent variability in road grade, vehicle driving patterns (speed, acceleration, deceleration, and idling), and meteorology. In a comparison of model predictions to measured PM2.5 concentrations, we found that the model estimated PM2.5 dispersion to within a factor of two for 75% of data points, which is within the typical benchmark used for model performance evaluation. Applying the model to present-day conditions in the study area, we found that current traffic contributes a relatively small amount to ambient PM2.5 concentrations: about 0.14 μg/m3 in the most exposed neighborhood—relatively low in comparison to the current US National Ambient Air Quality Standard of 12 μg/m3. Notably, even though the new campus is expected to bring an additional 40,000 daily trips to the study community by the year 2025, vehicle-related PM2.5 emissions are expected to decrease compared to current conditions due to anticipated improvements in vehicle technologies and cleaner fuels.

Experimental research on the development of residual strain in seasonal frozen soil under freezing-thawing and impact type traffic loads

Vehicle load is among the main factors affecting the deformation of subgrade soil.In this research study,the concept of impact type traffic load is introduced to investigate the effects of vehicle load based on the dynamic stress and displacement time histories acquired from seasonal frozen subgrade soils.Using freezing-thawing and dynamic triaxial tests and considering the amplitude and loading sequence of impact type traffic load,the residual deformation characteristics of subgrade soil under impact type traffic loads and freezing-thawing cycles is studied.It was found that under impact type traffic load,the residual deformation of soils increased sharply as the amplitude of impact type traffic load increased.It was also found that the increase in the amplitude of impact type traffic load led to the increase of residual deformation in a scale of power and exponential function.The amplitudes of impact type traffic load affect the development stress-strain path of the residual strain.After the soil experienced the proper amount of pre-vibration of the light load,residual deformation decreased by 15%.After freezing-thawing,the residual strain of soil increased as the amplitude of the impact type traffic loads increased.Also,when the amplification effect of freezing-thawing on the residual strain was basically stable,the residual deformation increased by about 10%.The peak impact type traffic load had a large effect on soil deformation after the freezing-thawing process,leading to the observation that of the earlier the peaks,the stronger the effect of freezing-thawing.After the soil was subjected to preloading with a small load,the influence of the freezing-thawing cycles gradually stabilized.The results may be useful in preventing and controlling the risk of subgrade soil failure when construction takes place spring thaw periods.

A Literature Review on Freeway Traffic Incidents and Their Impact on Traffic Operations

Congestion on the freeway is more frequent due to several traffic incidents, namely traffic accidents, debris on the road, vehicle breakdown, and collision with guardrails than any other incidents. These, in turn, affect the operational performance of the freeway by increasing queue length, volume, and density. Consequently, effective freeway management strategies can help to minimize these impacts. The study investigates and summarizes existing studies to identify the reasons for and effects of the traffic incidents. Attention is given to the available solutions of the freeway traffic incidents management. The ultimate goal of this study is to identify the gaps which are not yet addressed to improve the operational effectiveness of the freeway. This study was conducted through a comprehensive literature review of existing refereed publications, established standards, and formal guidelines. Literature was sought through the Transport Research International Documentation (TRID) database, IEEE Transactions database, and google scholar search engine. Research focusing on freeway traffic incidents is a growing concern in transportation operations, as transportation network performance depends on it. Due to the advancement of technology, emerging vehicle technologies like connected vehicles have the potential to address these problems affecting the US transportation system and revolutionize mobility in the future. The study can serve as a reference for the researchers that are involved in freeway traffic operations.

Railway Traffic Vibration Impact Analysis on Surrounding Buildings by FEM—Case Study: TER (Regional Express Train) Dakar—AIBD

The vibrations induced by railway traffic can affect the stability of structures, buildings and buried structures. To evaluate this impact, this study was carried out considering the case of the Regional Express Train which will connect Dakar to Blaise Diagne International Airport. For that, the modeling software Plaxis dynamic [1], able to generate harmonic loads, is used and permitted to have a dynamic analysis and comparison between static and dynamic load for one passage of the train for 2.56 s. In the modeling, two behavior laws were used those of Mohr Coulomb for the layers of soil, embankments and the form layer, and then the linear elastic model for the rest of the elements. The results obtained showed extreme vertical displacements 40.18 mm for the building and when no load is applied on the track, there was 40.24 mm for a static load, and 40.17 mm for a dynamic load. Also, it was observed for the track a displacement of 33.73 mm for a static load and 19.83 mm for a dynamic load. However, further studies are necessary to take into account the permanent deformation after an accurate cycle of train passage in order to better evaluate the railway traffic impact.

Study and Application of Evaluation Method for Weather Impact of Traffic Accident on Zhejiang Freeway

Occurrence degree of the accident on Zhejiang freeway is graded. Evaluation indicator system of weather impact on freeway is established. We use principal component analysis to extract meteorological indicators,and use Logistic regression to establish evaluation model of meteorological indicator,thereby determining evaluation grade of traffic weather impact. Via application test,it is proved that the evaluation on traffic weather condition by the model corresponds with actual situation,which can provide certain decision-making basis for traffic department and the public.

Impact of Ambient Air Pollution on Public Health under Various Traffic Policies in Shanghai,China

Objective To investigate the potential impact of ambient air pollution on public health under various traffic policies in Shanghai. Methods The exposure level of Shanghai residents to air pollution under various planned traffic scenarios was estimated, and the public health impact was assessed using concentration-response functions derived from available epidemiological studies. Results Our results showed that ambient air pollution in relation to traffic scenarios had a significant impact on the future health status of Shanghai residents. Compared with the base case scenario, implementation of various traffic scenarios could prevent 759-1574, 1885-2420, and 2277-2650 PM10-related avoidable deaths （mean-value） in 2010, 2015, and 2020, respectively. It could also decrease the incidence of several relevant diseases. Conclusion Our findings emphasize the need to consider air pollution-related health effects as an important impact of traffic policy in Shanghai.

Design of Bridge Expansion Joints with Perforated Dowels Under Impact Loading

The expansion joints are expected to have movement capacity, bearing capacity for static and dynamic loading, water-tightness, low noise emission and traffic safety. In particular, the failure due to impact loading is the main reason for the observed damages. The problem of dynamic behavior of the expansion joints is so complex that we shall focus our attention on the impact factor for vehicle load that is governed by traffic impact. In order to overcome this difficulty, the cantilever-toothed aluminum joint (finger joint) is one of the promising joints under impact loading. In this study, from the viewpoint of design methodology, numerical studies for impact behavior were conducted for aluminum alloy expansion joints with perforated dowels. The design impact factor for the expansion joints with the perforated dowels against traffic impact loading was examined by using numerical simulations.

A Model for Capacity Considering the Interference by Pedestrian Traffic at Signal Intersections

The capacity is impacted badly by pedestrians' violation behavior at signal intersections. In order to quantify the impact,the time-headway and the vehicular speed from start-up to reach the stable saturation flow with and without pedestrian traffic are used as the direct measurements. Using the statistical analysis,the timeheadway of saturation flow is mainly affected by the position of pedestrians and the degree of pedestrians 'influence is classified into four levels. Then the speed-time profile for the vehicular acceleration at each level is fitted by Curve Fitting Software. Based on the effect to the time-headway and acceleration time,the model of capacity influenced by pedestrians is established and the influence is quantified, which enriches the fundamental theory of traffic engineering. The result shows that the vehicular capacity can be decreased by 14%at the worst case( level I). The conclusions obtained in this paper are valuable for better management of the signal intersection.

国土空间规划背景下交通详细规划体系探究

国土空间规划体系的建立对现行城市规划的编制、实施、管理提出全新要求。该文在现行详细规划体系中交通规划内容存在的主要问题基础上,结合新规划体系中详细规划发展趋势及要求,进一步明确交通详细规划的定位和作用,提出交通详细规划的初步理论框架设计,包括技术支撑体系和规划编管体系,并给出两大体系的规划技术方法、内容指引要求和规划编制、实施、管控、监督等相关建议,为后续国土空间详细规划编管提供一定的技术支撑和操作建议。

基于Vissim仿真系统的公共停车楼交通影响评估

为避免大型公共停车楼建成后,产生吸引的交通量对周边道路交通产生严重影响。该文以重庆礼嘉公共停车楼为例,开展交通影响评估工作。首先,采用传统的“四阶段”法,对停车楼建成后早晚高峰时段周边路段交通量变化进行预测分析;其次,借助Vissim仿真软件进行模拟评估,对公共停车楼建成前后城市路网进行交通仿真应用,得到客观评估结论,从而为规划管理部门提供决策参考。

考虑交通事件影响的高速公路短时行程时间预测

本研究目的是基于历史行程数据并考虑交通事件,构建可提高高速公路短时行程时间预测精度的方法。基于深层机器学习理论,设计加权均方根相似(Weighted-RMSS)模型,利用经纬度将行程分段,考虑高速公路车辆时空流动性的时间传递,计算当前行程时间和历史案例行程时间的相似性,提高了行程时间预测精确度。在此基础上,结合交通事件数据建立交通事件影响矩阵,建立LGBM模型(Light Gradient Boosting Machine)用于短时行程时间预测,并利用广州高速公路平沙至机场南路段实测数据进行验证。研究结果表明,开发2个模型效果均优于传统KNN模型,且考虑了交通事件影响的LGBM模型的预测精度高于Weighted-RMSS模型,达到95.68%,比较不同未来预测时间得出预测5 min效果最佳,精度可达96.18%。本研究在短时行程时间预测上有显著的优越性,有助于为驾驶人提供准确的出行时间,有利于高速公路的交通管理。

莫干山快速路总体建设形式方案设计

快速路位居城市道路4个等级中的顶端,完全为交通功能服务,是解决城市大容量、中长距离、快速交通的道路。快速路的建设形式需要根据不同地区、不同情况,进行全面的、综合的影响评估。通过杭州莫干山快速路设计实例,从交通量分析入手,确定快速路的规模等级,然后从快速路与起、终点的衔接,对地面桥梁及轨道交通的影响等方面,对高架快速路和隧道快速路两种形式进行了对比论证,分析了相关条件制约下快速路形式的选择。

青岛第二条海底隧道黄岛端道路交通衔接规划研究

青岛胶州湾第二海底隧道联系了老黄岛与东岸城区,对加强胶州湾东西两岸的交通联系具有重要意义,目前已经开工建设。为满足隧道黄岛端交通疏解需求,提高交通运行效率,现对二隧黄岛端骨干路网交通衔接方案进行研究。在分析黄岛端区域现状及规划条件的基础上,预测过海出行需求,并分析隧道对区域路网的交通影响,提出黄岛端接线道路提升优化建议及建设时序,最后对淮河路、疏港高架、黄河路道路提升改造总体方案进行研究,旨在为后续道路建设提供方案借鉴。

区域交通评估中的交通设施用地匹配关系研究

交通设施用地的匹配关系是区域交通评估工作的重要组成部分.以城市道路用地、地面公共交通场站及社会停车场3类交通设施用地为例,探讨了各类交通设施用地的核心要求与匹配关系.结果表明,在区域交通评估工作中,对城市道路用地的核心要求为空间布局和路网密度,地面公共交通场站及社会停车场用地的核心要求为空间布局和用地面积,通过实际案例对交通设施用地匹配可能存在的典型问题提出了改善建议.

网联进口道考虑信号影响混合基本图研究

为研究含网联自动驾驶、自动驾驶和人工驾驶车辆的混合交通流在交叉口进口道受信号影响的混合基本图变化情况,构筑信号影响下的混合交通流跟驰模型,并进行混合基本图数值仿真。结果表明,同质交通流下CAV和AV能增加进口道最大通行能力,为12.47%和4.99%;信号信息能一定程度影响交叉口进口道通行能力;增加渗透率P能够提高混合交通流于交叉口进口道通行能力,当混合交通流为最佳密度时,渗透率为0.9、0.5,相较于0.1,进口道通行能力分别提高10.71%和6.52%。

智轨交通系统交通影响评价及在城市规划上的应用

为了研究智能轨道快运列车对道路交通系统服务水平的影响,以某市市区占用道路资源的智能轨道快运列车项目为例,通过模型对规划方案进行评测,计算项目建成投入使用后对道路交通影响的程度,针对评价结果进行方案优化,并对有无智轨项目进行相关指标对比分析。研究发现:①部分重点区域存在交叉口组织混乱、信号控制不协调、交通设施不完善等问题;部分车站人行过街设施不足,需进行方案优化调整。②主要对路网改善、交叉口渠化、重点片区、沿线地块开口、慢行设施等进行优化调整,有效降低智轨交通系统对沿线及周边道路的交通影响,使得设计方案更符合区域整体交通发展需要。③城市中心区建设智轨项目联系外围新城,不会对当地交通造成消极影响。