穿村镇公路交叉口车辆速度特性及行车安全评价

乡村振兴战略下的穿村镇公路事故治理是重大现实问题,而穿村镇公路交叉口速度特性分析与行车安全评价已经成为迫切的理论需求。选择云南省2个典型穿村镇公路交叉口为实例,采集无人机视频数据以分析穿村镇公路交叉口的车辆速度变化规律;构建危险性系数模型与Vague复合物元行车安全等级判定模型,评估穿村镇公路交叉口行车安全水平,并通过实例交叉口进行验证。结果表明：穿村镇公路交叉口车辆运行速度总体呈现“减速—加速”模式,速度最低点位于交叉口中心附近;路况复杂的多路交叉口速度分布于[40, 65] km/h,波动幅度相对较小;相较于无路侧干扰的行驶场景,避让场景下交叉口车速离散度更大,车速差最大值为49.78 km/h。评价案例交叉口的行车安全性,发现车辆驶入时距交叉口中心越近,危险性系数越大,驶出时则反之;两个案例交叉口的危险性系数最大值均位于交叉口中心,该位置加速度变化最快,行车安全性最低;十字交叉口行车安全性更差,易发生交通事故,多路交叉口的行车安全性良好。研究成果可为穿村镇公路事故治理提供理论依据。     

强降雨环境下公路车辆制动安全性分析

为分析强降雨环境下公路车辆的制动安全可靠性，基于2种停车视距模型引入可靠性理论，将降雨强度、车速及驾驶员思索时间视为随机变量，运用蒙特卡罗模拟方法建立强降雨环境下公路车辆制动安全可靠性分析模型，以研究不同降雨强度、不同车速下公路车辆的停车视距。研究结果表明：降雨强度一定时，2种计算模型的停车视距差值随着车速的增大而增大，车速一定时，2种计算模型的停车视距差值随着降雨强度的增大基本不变；若随机变量服从正态分布，停车视距也近似服从正态分布，且模型Ⅱ的分布均值大于模型Ⅰ,模型Ⅱ的分布标准差近似于模型Ⅰ;车辆的制动失效概率随着车速及降雨强度的增大而增大，车速及降雨强度一定时，基于模型Ⅱ计算的车辆制动失效概率略高于模型Ⅰ;车辆的临界车速随着降雨强度的增大而降低，随着制动失效概率的增大而增大，车辆制动失效概率及降雨强度一定时，基于模型Ⅰ计算的临界车速略高于模型Ⅱ;较传统确定性方法相比，基于可靠性方法可以获得更为合理的雨天行车安全临界车速，当降雨强度为4mm/min,失效概率为0.000 1时，临界车速已低于45km/h。     

基于TCT的平面交叉口安全评价方法研究

事故率法是评价平面交叉口交通安全水平常用的方法之一,但因其存在基于事故统计方法固有的因事故的稀有性而使评价周期过长、因事故统计的不完全性致使评价结论欠真、缺乏事故严重性程度的考虑等缺点。笔者针对事故率法评价交叉口安全水平存在的上述问题,在概要介绍交通冲突技术并对交通冲突技术的有效性进行分析的基础上,提出了使事故率法与交通冲突技术相结合,用交通冲突代替交通事故改善交叉口事故率法的理论设想。进而,结合质量控制法,研究了同类型交叉口的交通冲突率的临界值的确定,提出了基于交通冲突技术和交叉口交通冲突率的评价方法。     

高等级公路车速管理研究

高等级公路交通事故中约 1/ 3与车速直接相关。为保证高等级公路行车安全 ,车速管理非常必要。从我国高等级公路管理现状出发 ,根据对我国高等级公路车辆实际运行特征和运行车速的实地调查 ,笔者对高等级公路车速限制的设定、发布及实施进行了研究 ,提出了应根据公路、交通、气象、历史事故数据等条件动态确定限制车速的概念 ,并就高等级公路车速管理的实施进行了探讨 ,重点强调了道路设计和交通安全文化建设在实施车速管理中的重要性。     

农村公路交叉口交通事故特征关联性与风险因素分析

为降低农村公路交叉口事故风险,提取环境、道路、设施、车型和违法行为特征作为自变量,以事故形态和事故严重程度为因变量,构建考虑因变量内在关联的双变量Probit模型,分析二者的相关性,并识别显著影响因素。结果表明:农村公路交叉口交通事故形态和严重程度呈负相关关系,单车事故的死亡率更高;线形越好,隔离、控制设施越完备,事故严重性越低;车型越大,事故后果越严重;违法行为增加了发生致死性单车事故的概率。在交叉口处增设安全保障设施,对相交公路等级差异较大的路口实行限速管理,加强对大型车辆和摩托车的安全管理,加强对无证驾驶行为的处罚,可以改善农村公路交叉口安全水平。     

铁路道口安全影响因素分析及对策

在对比分析中外铁路道口安全形势及研究现状的基础上,从人、车、道口几何特性、安全防护装置、管理及环境等因素出发,系统地分析了铁路道口安全及其影响因素:1)汽车驾驶员酒后驾驶、超速驾驶、疲劳驾驶等人为违章行为是道口事故的主要致因;2)车辆机械故障、超载是影响道口安全不容忽视的重要因素;3)道口坡度、铺面、视距等道口几何特性与道口事故频率有着紧密联系;4)道口交通信号、车速监控器及惩罚对提高驾驶员的安全行为有显著作用;5)完善的应急医疗体系将大大减少道口事故的伤亡.进而从工程、教育和法制3方面提出了我国改善道口安全状况的措施和建议,包括:安装悬臂梁警告装置,施划减速标线,改造道口铺面,加大酒后驾驶惩罚力度,宣传道口安全知识等.     

地铁运营安全风险管理现状分析

对国内轨道交通通车里程和在建里程进行统计,并对国际重大地铁事故进行简单统计分析,指出造成地铁安全风险事故的主要原因。在此基础上,对地铁运营安全风险管理的特点和定义进行探讨,并进一步介绍国内外大型城市地铁运营的典型风险管理体系,探讨地铁运营过程中的风险管理特点及现状,对比分析国内外地铁运营管理体系的异同点。指出目前国内地铁运营风险管理中存在的主要问题,并针对其中问题提出具体的建议性措施。     

云南山区公路事故多发路段安全对策措施研究

分析云南山区公路严峻的交通形势,及山区公路交通事故的特征、事故形态及影响因素,研究山区公路交通事故发生的机理。从人、车、路和环境等方面分析事故产生的原因,提出针对云南山区事故多发路段安全对策措施。分析表明,在云南山区,路况、人员安全素质、车辆性能、安全管理均处于较低水平,是重大事故多发的根本原因。提高系统安全性,实现系统功能最强,应使系统各要素相互匹配,以实现本质安全。     

高速公路安全改善项目方案决策研究

针对我国高速公路运营安全特点,在对事故资料、道路设计资料的收集与分析的基础上,将事故黑点和事故多发路段类型划分为撞固定物、追尾及其组合不同类型。结合现场交通运行环境与运行状态调查,分析事故黑点和事故多发路段的成因,提出安全改善对策研究的基本原则,并有针对性地进行了安全改善对策研究,建立高速公路事故黑点和事故多发路段安全改善工程对策集。在决策方法研究中,总结常用安全改善对策的可能效果,提出高速公路安全改善项目方案决策的原则,研究了安全改善对策选择的效用决策方法,并进行了案例分析。     

城市道路交叉口交通安全水平评价及改善对策研究

针对国内外利用历史性的事故统计资料来评价城市道路交叉口交通安全水平的缺陷和不足,笔者结合我国道路交通安全管理的特点,提出一种以交通冲突技术和灰色理论为理论依据的城市交叉口交通安全评价方法。应用该方法,对山东省潍坊市市区48个城区交叉口的交通安全状况进行评价,并根据评价结果提出交叉口的几点改善对策。实证表明:该方法能有效解决城市道路交叉口安全性评价问题,取得比较满意的结果。     

Analyses of rear-end crashes based on classification tree models

OBJECTIVE: Signalized intersections are accident-prone areas especially for rear-end crashes due to the fact that the diversity of the braking behaviors of drivers increases during the signal change. The objective of this article is to improve knowledge of the relationship between rear-end crashes occurring at signalized intersections and a series of potential traffic risk factors classified by driver characteristics, environments, and vehicle types. METHODS: Based on the 2001 Florida crash database, the classification tree method and Quasi-induced exposure concept were used to perform the statistical analysis. Two binary classification tree models were developed in this study. One was used for the crash comparison between rear-end and non-rear-end to identify those specific trends of the rear-end crashes. The other was constructed for the comparison between striking vehicles/drivers (at-fault) and struck vehicles/drivers (not-at-fault) to find more complex crash pattern associated with the traffic attributes of driver, vehicle, and environment. RESULTS: The modeling results showed that the rear-end crashes are over-presented in the higher speed limits (45-55 mph); the rear-end crash propensity for daytime is apparently larger than nighttime; and the reduction of braking capacity due to wet and slippery road surface conditions would definitely contribute to rear-end crashes, especially at intersections with higher speed limits. The tree model segmented drivers into four homogeneous age groups: < 21 years, 21-31 years, 32-75 years, and > 75 years. The youngest driver group shows the largest crash propensity; in the 21-31 age group, the male drivers are over-involved in rear-end crashes under adverse weather conditions and the 32-75 years drivers driving large size vehicles have a larger crash propensity compared to those driving passenger vehicles. CONCLUSIONS: Combined with the quasi-induced exposure concept, the classification tree method is a proper statistical tool for traffic-safety analysis to investigate crash propensity. Compared to the logistic regression models, tree models have advantages for handling continuous independent variables and easily explaining the complex interaction effect with more than two independent variables. This research recommended that at signalized intersections with higher speed limits, reducing the speed limit to 40 mph efficiently contribute to a lower accident rate. Drivers involved in alcohol use may increase not only rear-end crash risk but also the driver injury severity. Education and enforcement countermeasures should focus on the driver group younger than 21 years. Further studies are suggested to compare crash risk distributions of the driver age for other main crash types to seek corresponding traffic countermeasures.     

基于速度特征指标的高速公路线形一致性综合评价

为量化评价已建和拟建高速公路交通安全性,以实测运行车速数据和事故率数据为基础,根据公路空间属性的变化,采用不定长法进行路段划分。考虑不同路段车速协调性和连续性的需求,引入客货差极差比、车速降低系数、路段车速离散度等车速特征指标。通过对运行车速特征指标与事故率的相关性分析,采用多元回归的方法建立了高速公路线形设计一致性综合评价模型,同时结合事故多发点改善效果的显著性,确定我国高速公路安全性服务水平,在此基础上提出线形设计一致性评价标准和评价方法。太旧高速公路的实例应用结果表明,该方法可准确有效地评价线形设计一致性。     

An investigation on multi-vehicle motorcycle crashes using log-linear models

Motorcyclists are the most crash-prone road-user group in many Asian countries including Singapore; however, factors influencing motorcycle crashes are still not well understood. This study examines the effects of various roadway characteristics, traffic control measures and environmental factors on motorcycle crashes at different location types including expressways and intersections. Using techniques of categorical data analysis, this study has developed a set of log-linear models to investigate multi-vehicle motorcycle crashes in Singapore. Motorcycle crash risks in different circumstances have been calculated after controlling for the exposure estimated by the induced exposure technique. Results show that night-time influence increases crash risks of motorcycles particularly during merging and diverging manoeuvres on expressways, and turning manoeuvres at intersections. Riders appear to exercise more care while riding on wet road surfaces particularly during night. Many hazardous interactions at intersections tend to be related to the failure of drivers to notice a motorcycle as well as to judge correctly the speed/distance of an oncoming motorcycle. Road side conflicts due to stopping/waiting vehicles and interactions with opposing traffic on undivided roads have been found to be as detrimental factors on motorcycle safety along arterial, main and local roads away from intersections. Based on the findings of this study, several targeted countermeasures in the form of legislations, rider training, and safety awareness programmes have been recommended.     

Driver behavior analysis for right-turn drivers at signalized intersections using SHRP 2 naturalistic driving study data

IntroductionUnderstanding driver behavior is important for traffic safety and operation, especially at intersections where different traffic movements conflict. While most driver-behavior studies are based on simulation, this paper documents the analysis of driver-behavior at signalized intersections with the SHRP 2 Naturalistic Driving Study (NDS) data. This study analyzes the different influencing factors on the operation (speed control) and observation of right-turn drivers.MethodA total of 300 NDS trips at six signalized intersections were used, including the NDS time-series sensor data, the forward videos and driver face videos. Different factors of drivers, vehicles, roads and environments were studied for their influence on driver behavior. An influencing index function was developed and the index was calculated for each influencing factor to quantitatively describe its influencing level. The influencing index was applied to prioritize the factors, which facilitates development and selection of safety countermeasures to improve intersection safety. Drivers' speed control was analyzed under different conditions with consideration of the prioritized influencing factors.ResultsVehicle type, traffic signal status, conflicting traffic, conflicting pedestrian and driver age group were identified as the five major influencing factors on driver observation.ConclusionsThis research revealed that drivers have high acceleration and low observation frequency under Right-Turn-On-Red (RTOR), which constituted potential danger for other roadway users, especially for pedestrians.Practical applicationsAs speed has a direct influence on crash rates and severities, the revealed speed patterns of the different situations also benefit selection of safety countermeasures at signalized intersections.     

Crash analysis and development of safety performance functions for Florida roads in the framework of the context classification system

Introduction: Safety performance functions (SPF) are employed to predict crash counts at the different roadway elements. Several SPFs were developed for the various roadway elements based on different classifications such as functional classification and area type. Since a more detailed classification of roadway elements leads to more accurate crash predictions, multiple states have developed new classification systems to classify roads based on a comprehensive classification. In Florida, the new roadway context classification system incorporates geographic, demographic, and road characteristics information. Method: In this study, SPFs were developed in the framework of the FDOT roadway context classification system at three levels of modeling, context classification (CC-SPFs), area type (AT-SPFs), and statewide (SW-SPF) levels. Crash and traffic data from 2015-2019 were obtained. Road characteristics and road environment information have also been gathered along Florida roads for the SPF development. Results: The developed SPFs showed that there are several variables that influence the frequency of crashes, such as annual average daily traffic (AADT), signalized intersections and access point densities, speed limit, and shoulder width. However, there are other variables that did not have an influence in crash occurrence such as concrete surface and the presence of bicycle slots. CC-SPFs had the best performance among others. Moreover, network screening to determine the most problematic road segments has been accomplished. The results of the network screening indicated that the most problematic roads in Florida are the suburban commercial and the urban general roads. Practical Applications: This research provides a solid reference for decision-makers regarding crash prediction and safety improvement along Florida roads.     

Analysis of driver injury severity levels at multiple locations using ordered probit models

Problem: The occurrence and outcome of traffic crashes have long been recognized as complex events involving interactions between many factors, including the roadway, driver, traffic characteristics, and the environment. This study is concerned with the outcome of the crash. Method: Driver injury severity levels are analyzed using the ordered probit modeling methodology. Models were developed for roadway sections, signalized intersections, and toll plazas in Central Florida. All models showed the significance of driver's age, gender, seat belt use, point of impact, speed, and vehicle type on the injury severity level. Other variables were found significant only in specific cases. Results: A driver's violation was significant in the case of signalized intersections. Alcohol, lighting conditions, and the existence of a horizontal curve affected the likelihood of injuries in the roadway sections' model. A variable specific to toll plazas, vehicles equipped with Electronic Toll Collection (ETC), had a positive effect on the probability of higher injury severity at toll plazas. Other variables that entered into some of the models were weather condition, area type, and some interaction factors. This study illustrates the similarities and the differences in the factors that affect injury severity between different locations.     

A simultaneous equations model of crash frequency by collision type for rural intersections

Safety at roadway intersections is of significant interest to transportation professionals due to the large number of intersections in transportation networks, the complexity of traffic movements at these locations that leads to large numbers of conflicts, and the wide variety of geometric and operational features that define them. A variety of collision types including head-on, sideswipe, rear-end, and angle crashes occur at intersections. While intersection crash totals may not reveal a site deficiency, over exposure of a specific crash type may reveal otherwise undetected deficiencies. Thus, there is a need to be able to model the expected frequency of crashes by collision type at intersections to enable the detection of problems and the implementation of effective design strategies and countermeasures. Statistically, it is important to consider modeling collision type frequencies simultaneously to account for the possibility of common unobserved factors affecting crash frequencies across crash types. In this paper, a simultaneous equations model of crash frequencies by collision type is developed and presented using crash data for rural intersections in Georgia. The model estimation results support the notion of the presence of significant common unobserved factors across crash types, although the impact of these factors on parameter estimates is found to be rather modest.     

Effects of red light camera enforcement on fatal crashes in large U.S. cities

Objective

To estimate the effects of red light camera enforcement on per capita fatal crash rates at intersections with signal lights.

Methods

From the 99 large U.S. cities with more than 200,000 residents in 2008, 14 cities were identified with red light camera enforcement programs for all of 2004-2008 but not at any time during 1992-1996, and 48 cities were identified without camera programs during either period. Analyses compared the citywide per capita rate of fatal red light running crashes and the citywide per capita rate of all fatal crashes at signalized intersections during the two study periods, and rate changes then were compared for cities with and without cameras programs. Poisson regression was used to model crash rates as a function of red light camera enforcement, land area, and population density.

Results

The average annual rate of fatal red light running crashes declined for both study groups, but the decline was larger for cities with red light camera enforcement programs than for cities without camera programs (35% vs. 14%). The average annual rate of all fatal crashes at signalized intersections decreased by 14% for cities with camera programs and increased slightly (2%) for cities without cameras. After controlling for population density and land area, the rate of fatal red light running crashes during 2004-2008 for cities with camera programs was an estimated 24% lower than what would have been expected without cameras. The rate of all fatal crashes at signalized intersections during 2004-2008 for cities with camera programs was an estimated 17% lower than what would have been expected without cameras.

Conclusions

Red light camera enforcement programs were associated with a statistically significant reduction in the citywide rate of fatal red light running crashes and a smaller but still significant reduction in the rate of all fatal crashes at signalized intersections.

Impact on Industry

The study adds to the large body of evidence that red light camera enforcement can prevent the most serious crashes. Communities seeking to reduce crashes at intersections should consider this evidence.     

Effects of red light running camera systems installation and then deactivation on intersection safety

IntroductionThe primary objective of this paper is to evaluate the safety impacts of red-light running camera (RLC) system installation and then deactivation at 48 intersections in Houston, Texas. The second objective is to evaluate the spillover effect at nearby non-treated intersections in Houston after the deactivation.MethodsTo accomplish study objectives, an Empirical Bayes (EB) before-after analysis was used.ResultsThe results indicate statistically significant collision reductions on all red-light running (RLR) crash types (37 percent) as well as right-angle RLR crashes (47 percent) at the treated intersections after RLC activation. By way of comparison, the RLC deactivation analysis indicated that crashes increased by 20 percent for all RLR crash types and by 23 percent in right-angle RLR crashes at the formerly treated intersections. After deactivation, all severity RLR crashes increased more than expected at nearby non-treated intersections, which indicates the possibility of an adverse spillover effect. However, fatal/injury crashes associated with rear-end decreased after deactivation at both formerly treated and non-treated intersections, although those rear-end crashes account for smaller proportions when compared to all crash types/right-angle crashes.Practical applicationsOverall, removing RLC treatments results in a negative reaction to the safety benefits that the treatment provides when it is in place and actively working and to the nearby intersections where the treatment has not been implemented. This study helps define the effects that RLCs have on safety at signalized intersections after installation and deactivation.     

Quantifying the impact of adaptive traffic control systems on crash frequency and severity: Evidence from Oakland County,Michigan

IntroductionDespite seeing widespread usage worldwide, adaptive traffic control systems have experienced relatively little use in the United States. Of the systems used, the Sydney Coordinated Adaptive Traffic System (SCATS) is the most popular in America. Safety benefits of these systems are not as well understood nor as commonly documented.MethodThis study investigates the safety benefits of adaptive traffic control systems by using the large SCATS-based system in Oakland County, MI known as FAST-TRAC. This study uses data from FAST-TRAC-controlled intersections in Oakland County and compares a wide variety of geometric, traffic, and crash characteristics to similar intersections in metropolitan areas elsewhere in Michigan. Data from 498 signalized intersections are used to conduct a cross-sectional analysis. Negative binomial models are used to estimate models for three dependent crash variables. Multinomial logit models are used to estimate an injury severity model. A variable tracking the presence of FAST-TRAC controllers at intersections is used in all models to determine if a SCATS-based system has an impact on crash occurrences or crash severity.ResultsEstimates show that the presence of SCATS-based controllers at intersections is likely to reduce angle crashes by up to 19.3%. Severity results show a statistically significant increase in non-serious injuries, but not a significant reduction in incapacitating injuries or fatal accidents.