Developing travel time estimation methods using sparse GPS data

Existing methods of estimating travel time from GPS data are not able to simultaneously take account of the issues related to uncertainties associated with GPS and spatial road network data. Moreover, they typically depend upon high-frequency data sources from specialist data providers, which can be expensive and are not always readily available. The study reported here therefore sought to better estimate travel time using “readily available” vehicle trajectory data from moving sensors such as buses, taxis, and logistical vehicles equipped with GPS in “near” real time. To do this, accurate locations of vehicles on a link were first map-matched to reduce the positioning errors associated with GPS and digital road maps. Two mathematical methods were then developed to estimate link travel times from map-matched GPS fixes, vehicle speeds, and network connectivity information with a special focus on sampling frequencies, vehicle penetration rates, and time window lengths. Global positioning system (GPS) data from Interstate I-880 (California) for a total of 73 vehicles over 6 h were obtained from the University of California Berkeley's Mobile Century Project, and these were used to evaluate several travel time estimation methods, the results of which were then validated against reference travel time data collected from high resolution video cameras. The results indicate that vehicle penetration rates, data sampling frequencies, vehicle coverage on the links, and time window lengths all influence the accuracy of link travel time estimation. The performance was found to be best in the 5-min time window length and for a GPS sampling frequency of 60 s.     

基于试验场道路的变速器台架载荷谱研究

通过实车采集试验样车在试验场道路上行驶时的CAN BUS数据,可直接获得发动机转速、扭矩和档位等信号;把传统的载荷-时间频次关系,转变为载荷-发动机飞轮旋转频次关系,同时记录各载荷等级对应的各个挡位的频次,这样可获得在各个档位下,不同载荷等级对应转速区间内的飞轮旋转频次,根据齿轮材料的S-N曲线和疲劳累积Miner理论,计算出各档位的疲劳强度,然后基本疲劳损伤等效原理选取各档位下产生较大疲劳强度的扭矩和转速,作为台架试验输入的载荷和转速,可有效避免载荷和转速选取的盲目性,为科学的制定台架试验载荷谱提供了依据。     

在公路普查中使用机读卡完成录入工作的设想

设计了使用智能光标字符阅读机的办法解决全国公路普查工作中“海量”数据录入的问题 ,对其可行性进行了分析并初步设计了普查使用的机读卡格式和样张 ,为公路普查工作中的数据录入提供了一个高精度的办法     

A framework for travel time variability analysis using urban traffic incident data

This study aims to develop a framework to estimate travel time variability caused by traffic incidents using integrated traffic, road geometry, incident, and weather data. We develop a series of robust regression models based on the data from a stretch in California's highway system during a two-year period. The models estimate highway clearance time and percent changes in speed for both downstream and upstream sections of the incident bottleneck. The results indicate that highway shoulder and lane width factor adversely impact downstream highway clearance time. Next, travel time variability is estimated based on the proposed speed change models. The results of the split-sample validation show the effectiveness of the proposed models in estimating the travel time variability. Application of the model is examined using a micro-simulation, which demonstrates that equipping travelers with the estimated travel time variability in case of an incident can improve the total travel time by almost 60%. The contribution of this research is to bring several datasets together, which can be advantageous to Traffic Incident Management.     

路面铣刨机铣削转予驱动马达工作负荷计算分析

通过对沥青路面常温破坏机理以及路面铣刨机刀具铣削阻力的分析,利用冲量定理,推导出铣刨机铣削转子驱动马达工作负荷的计算公式,为铣削转子驱动马达提供选型依据.     

路面铣刨机铣削转子驱动马达工作负荷计算分析

通过对沥青路面常温破坏机理以及路面铣刨机刀具铣削阻力的分析，利用冲量定理．推导出铣刨机铣削转子驱动马达工作负荷的计算公式，为铣削转了驱动马达提供选型依据。     

Bus travel time modelling using GPS probe and smart card data: A probabilistic approach considering link travel time and station dwell time

Abstract

Path travel time estimation for buses is critical to public transit operation and passenger information system. State-of-the-art methods for estimating path travel time are usually focused on single vehicle with a limited number of road segments, thereby neglecting the interaction among multiple buses, boarding behavior, and traffic flow. This study models path travel time for buses considering link travel time and station dwell time. First, we fit link travel time to shifted lognormal distributions as in previous studies. Then, we propose a probabilistic model to capture interactions among buses in the bus bay as a first-in-first-out queue, with every bus sharing the same set of behaviors: queuing to enter the bus bay, loading/unloading passengers, and merging into traffic flow on the main road. Finally, path travel time distribution is estimated by statistically summarizing link travel time distributions and station dwell time distributions. The path travel time of a bus line in Hangzhou is analyzed to validate the effectiveness of the proposed model. Results show that the model-based estimated path travel time distribution resembles the observed distribution well. Based on the calculation of path travel time, link travel time reliability is identified as the main factor affecting path travel time reliability.     

数据挖掘技术在交通事故黑点整治中的运用

目前我国城市道路交通事故频发,而许多城市道路事故黑点的整治工作仍然依靠人工或简单的数据库来进行。为了系统和科学地整治交通事故黑点,本文提出了利用数据预处理技术处理事故黑点数据库,运用关联规则技术分析黑点事故成因,为城市道路交通事故黑点的整治提供了有效的方法。     

EQ140汽车后桥的极值载荷分析及在疲劳试验中的应用

本文对汽车后桥的极值载荷进行了深入的分析，得出了确定最短测量里程和估算载荷谱极值载荷的方法，用此方法推断了三种典型载荷谱的极值载荷，建立了三种单一路面的程序疲劳试验者，进行了室内程序疲劳试验，得到了代表各种种面等级的极值载荷和使用寿命的统计关系。     

实测道路载荷谱在新开发车型车身疲劳分析中的应用

根据新研发车和现有车型具有相同底盘平台的特点,提出一种利用现车道路载荷,快速进行新车车身疲劳分析和评估的方法。建立新车多体模型,放大现车道路载荷并结合轮胎接地位移为输入。根据车轮力传感器(WFT)载荷测量特点,正确地对模型加载激励,仿真得到车身载荷谱。选用合理疲劳分析方法预测车身寿命,以现车车身的疲劳分析损伤为目标,对不合格局部进行合理优化,最终新车车身达到设计耐久目标。     

路面不平度的数学模型及计算机模拟研究

提出了一种一维路面不平度数学模型，即ＡＲＭＡ模型，统一地描述了复杂而且不规则的路面起伏形状，运用该模型进行了计算机数值模拟，对国标ＧＢ７０３１－８６《车辆振动输入路面平度表示方法》中规定的路面不平度模拟结果表明，该模型的模拟精度好，运算效率高，同时数字信号处理理论为该模型提供了严密的数学基础。     

基于GIS的城市道路管理系统的数据管理综合研究

40年的研究和实践已经使路面管理系统(PMS)成为管理部门进行养护规划以及道路养护投资的重要分析工具.目前,在GIS软件平台上实现PMS的功能已经成为当前PMS乃至设施管理研究与实践的重点,而各类PMS的基础仍然是数据的管理,即对数据的分类、组织、编码、储存、检索和维护等.就基于GIS的城市道路路面管理系统中的数据模型、数据通信、历史数据的存取与应用等有关数据管理的问题进行阐述,以期解决上述三个方面的部分普遍问题.     

载重车道路多点随机激励输入的时空相关性建模研究

为解决载重车动力学分析和车辆动态设计的道路建模问题,基于对车辆道路随机不平顺性态的分析,结合其在频域内的统计表示方法———功率谱密度函数,导出了载重车六轮激励输入的关于道路高程的功率谱矩阵,进而通过白噪声滤波方程得到了与给定谱特征相对应的道路时延相关性数学模型,提出了一种新的模拟双轮辙的过程和方法。通过应用该方法可以再现随机道路高程的有代表性的时间样本,为载重车线性和非线性平顺性动力学分析、悬架系统优化及整车振动控制提供模型基础。     

地质雷达在混凝土路面板脱空检测中的应用探讨

简述了脱空识别的方法,提出地质雷达应用到混凝土路面板下脱空的检测,克服了常规检测方法的局限性,为混凝土路面的预防性养护及维修提供了一种新的快速科学的检测方法。     

长期循环荷载作用下软粘土变形特性研究

在国内外有关长期循环荷载作用下粘土动力特性研究成果的基础上,探讨和分析了加载频率、加载类型、振幅与振次、排水条件等影响因素对软粘土变形的影响,并对长期循环荷载作用下软粘土累积变形的计算方法进行了归纳分析,最后对长期循环荷载作用下软粘土动力特性的进一步研究提出了建议。     

基于重载、重交通等特殊路段的水泥混凝土路面维修设计

从工程实际出发,提出了从基层处理、排水处治、面层结构计算等一整套针对重载、重交通、排水不畅等特殊条件路段的维修改造方案,为类似病害严重路段的维修改造提供了较好的借鉴.其中,排水盲沟设置、端部锚固处理等具有一定新意.     

基于GISDK进行公路网区域OD数据合成系统的开发研究

区域OD数据从空间和数量上综合描述了公路交通网络中交通需求的分布情况,是下一步进行交通需求预测的重要基础数据。文章提出在TransCAD软件平台上用宏模块嵌入的方式进行二次开发的设计思路,系统分析了公路网区域OD数据合成流程,设计了系统的四大功能模块,同时对OD合成的关键技术——串并联法和平行路法进行了修正和改进,并利用TransCAD二次开发工具GISDK加以实现,在此基础上建立的区域OD数据合成系统在实际路网中得到了应用和验证。     

Fatigue life estimation of injection mold core using simulation-based approach

The purpose of this study is to present a simulation-based approach capable of predicting the fatigue life of a mold core with the help of CAE technology based on injection molding simulation, core stress analysis and fatigue life prediction. Injection molding simulation is performed in order to obtain the non-uniform pressure acting on a mold core due to the polymer melt flow during injection molding process. Subsequently, the melt pressure profile is used as loading condition for core stress analysis via one-way coupling technique. The lifetime of a mold core is then predicted by fatigue analysis with stress-life approach. For verification of simulation-based approach to the fatigue life prediction, tests were also performed.     

半挂车车架多轴疲劳寿命研究

根据半挂车车架结构特点,建立了半挂车车架的有限元模型及多体动力学模型,对车架进行了静力学分析和以H级路面的路面载荷作为边界条件的动力学分析,得到了车架静态应力分布和载荷谱。并以此数据为依据,采用Wang-Brown多轴疲劳损伤模型预测了半挂车车架的多轴疲劳寿命,针对其疲劳薄弱部分提出了结构和工艺优化方案。优化后的车架满足使用寿命要求,且比原设计减重20%。