Examination of drivers' cell phone use behavior at intersections by using naturalistic driving data

IntroductionMany driving simulator studies have shown that cell phone use while driving greatly degraded driving performance. In terms of safety analysis, many factors including drivers, vehicles, and driving situations need to be considered. Controlled or simulated studies cannot always account for the full effects of these factors, especially situational factors such as road condition, traffic density, and weather and lighting conditions. Naturalistic driving by its nature provides a natural and realistic way to examine drivers' behaviors and associated factors for cell phone use while driving.MethodIn this study, driving speed while using a cell phone (conversation or visual/manual tasks) was compared to two baselines (baseline 1: normal driving condition, which only excludes driving while using a cell phone, baseline 2: driving-only condition, which excludes all types of secondary tasks) when traversing an intersection.ResultsThe outcomes showed that drivers drove slower when using a cell for both conversation and visual/manual (VM) tasks compared to baseline conditions. With regard to cell phone conversations, drivers were more likely to drive faster during the day time compared to night time driving and drive slower under moderate traffic compared to under sparse traffic situations. With regard to VM tasks, there was a significant interaction between traffic and cell phone use conditions. The maximum speed with VM tasks was significantly lower than that with baseline conditions under sparse traffic conditions. In contrast, the maximum speed with VM tasks was slightly higher than that with baseline driving under dense traffic situations.Practical applicationsThis suggests that drivers might self-regulate their behavior based on the driving situations and demand for secondary tasks, which could provide insights on driver distraction guidelines. With the rapid development of in-vehicle technology, the findings in this research could lead the improvement of human-machine interface (HMI) design as well.     

Traffic rules and traffic safety

In the present paper the effects of traffic rules on driver behaviour and on traffic safety are discussed. The discussion is mainly based on research conerning driver’s use of safety equipment, their speed adjustment and drunken driving with respect to safety potential, effects of the rules, and effects of enforcement on driver behaviour. Factors influencing drivers’ decisions to comply with rules are also considered. It is concluded that only rules that are possible to enforce should be implemented and that police surveillance should be visible to the drivers. Also, the traffic system should be seen as a social system where drivers are interacting with other drivers and road users. Rules and regulations are important to help the actors of the system to function in a safe and effective way.     

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.     

Fatigued driver’s driving behavior and cognitive task performance: Effects of road environments and road environment changes

This study aims to explore the effects of different road environments and their changes on driving behaviors and cognitive task performance of fatigued drivers. Twenty-four participants volunteered in a 2 (road environment) × 3 (fatigue level) within-subjects factorial design simulated driving experiment. Participants were asked to perform basic numerical calculation and distance estimation of traffic signs when driving normally, and provide answers to a questionnaire on fatigue rating. Results show that fatigued drivers faced greater attention demand, were less alert, and tended to overestimate the distance to roadside traffic signs. Fatigue caused by driving in complex road environment had the greatest negative impact on driving behavior and visual distance estimation, and the fatigue transfer effect worsened significantly but differently on both driving behavior and performance of fatigued drivers when switching from a complex to a monotonous road environment and vice versa. Notably, this study shows that fatigued drivers performed relatively better in arithmetic tasks than non-fatigued ones. In addition, when switching from a monotonous to a complex road environment, drivers’ performance in visual distance estimation and arithmetic tasks improved though their driving behavior deteriorated, revealing that the fatigue effect upon drivers might be explained to some extent by their alertness and arousal levels.     

Associations between driver training, determinants of risky driving behaviour and crash involvement

The core aim of the study is to examine associations between formal and informal practical driver training as well as driving experience on the one hand and young drivers’ safety attitudes, self-assessment of driving ability and self-reported driver behaviour on the other hand. An additional aim is to examine the associations between attitudes, self-assessment and behaviour on the one hand and crash involvement on the other hand. The results are based on a self-completion questionnaire survey conducted among a representative sample of Norwegian drivers aged 18–20 years (n = 1419). The results showed that there were small yet significant associations between driver training, on the one hand and traffic safety attitudes and risky driving behaviour on the other hand. The amount of formal driver training was negatively associated with the respondents’ evaluation of their driving skills; although the amount of lay instruction was positively associated with such self-evaluation. The results also showed that attitudes as well as self-assessment of driving ability were significantly associated with self-reported risk behaviour. This was especially true for attitudes related to rule violations. There was a strong association between crash involvement and exposure (measured as months holding a licence). Young novice drivers’ crash involvement seems stronger associated with driving skills (manifested as self-assessment of driving ability) than safety attitudes and self-reported driver behaviour. The consequences of the results for driver training and accident prevention are discussed.     

三岔型枢纽互通事故高发匝道的形成机制与安全提升研究*

为研究高速公路三岔型互通右转匝道车辆事故的发生机制,以宜宾至叙永高速公路双桥枢纽互通为对象,运用Carsim/trucksim软件建立事故匝道的三维数字模型,模拟小客车和货柜车的运行过程,设置3种不同工况,对车辆在匝道上的动力学特性进行分析。结果表明:行驶速度升高会导致匝道路段的车辆横向偏离增大,发生侧滑或侧翻的几率增加;充分制动距离是保证车辆安全通过匝道受限路段的重要因素,货车需要更长的制动距离;道路视觉环境是影响驾驶人速度选择行为的重要因素,匝道路段与高速公路主线行驶环境的高度近似,导致驾驶人选择较高的速度进入匝道,部分车辆在小半径弯道之前无法将速度降低至安全速度,进而发生事故。本文运用行车动力学仿真和驾驶人视觉手段,在驾驶行为层面分析事故的形成机制,进而提出安全提升措施,可为匝道线形设计和交通运行管理提供科学依据。     

Effects of lead time of verbal collision warning messages on driving behavior in connected vehicle settings

IntroductionUnder the connected vehicle environment, vehicles will be able to exchange traffic information with roadway infrastructure and other vehicles. With such information, collision warning systems (CWSs) will be able to warn drivers with potentially hazardous situations within or out of sight and reduce collision accidents. The lead time of warning messages is a crucial factor in determining the effectiveness of CWSs in the prevention of traffic accidents. Accordingly, it is necessary to understand the effects of lead time on driving behaviors and explore the optimal lead time in various collision scenarios.MethodsThe present driving simulator experiment studied the effects of controlled lead time at 16 levels (predetermined time headway from the subject vehicle to the collision location when the warning message broadcasted to a driver) on driving behaviors in various collision scenarios.ResultsMaximum effectiveness of warning messages was achieved when the controlled lead time was within the range of 5 s to 8 s. Specifically, the controlled lead time ranging from 4 s to 8 s led to the optimal safety benefit; and the controlled lead time ranging from 5 s to 8 s led to more gradual braking and shorter reaction time. Furthermore, a trapezoidal distribution of warning effectiveness was found by building a statistic model using curve estimation considering lead time, lifetime driving experience, and driving speed.ConclusionsThe results indicated that the controlled lead time significantly affected driver performance.Practical applicationsThe findings have implications for the design of collision warning systems.     

Risky behavior of drivers of motorized two wheeled vehicles in India

INTRODUCTION: Motorized two-wheeled vehicles (MTV) account for a large proportion of road traffic in India and the riders of these vehicles have a high risk of road traffic injuries. We report on the availability of drivers licenses, use of a helmet, driver behavior, and condition of vehicles for MTV drivers in Hyderabad, a city in India METHODS: Drivers of a MTV aged >16 years were interviewed at petrol filling stations RESULTS: There were 4,183 MTV drivers who participated in the study. Four hundred sixty one (11%; 95% CI 9.7-12.3%) drivers had not obtained a drivers license and 798 (21.4%) had obtained a license without taking the mandatory driving test. Two thousand nine hundred twenty (69.8%; 95% CI 67.9-71.7%) drivers reported no/very occasional use of a helmet, the significant predictors of which included that those driving borrowed a MTV (odds ratio 7.90; 95% CI 3.40-18.40) or driving moped/scooterette/scooter as compared with motorcycle (3.32; 2.76-3.98), lower education (3.10; 2.66-3.61), age >45 years (2.41; 1.63-3.57), and males (1.57; 1.16-2.13). Two thousand five hundred and eight (59.9%) drivers reported committing a traffic law violation at least once within the last 3 months. Overall, 1,222 (29.2%) drivers reported ever being caught by traffic police for a traffic law violation with data on violations available for 1,205 of these drivers, of whom 680 (56.4%) paid a fine, 310 (25.7%) paid by bribe, and 215 (17.8%) made no payment. The proportion of those who did not make payment for committed violation was significantly higher among females (46.8%) than males (16.3%). Two thousand fifty two (49%) of all MTVs had no rearview mirror CONCLUSIONS: These data suggest the need to enact and enforce policy interventions for improving the drivers license system, mandatory use of a helmet, effective traffic law enforcement, and ensuring good vehicle condition to reduce the risk factors that potentially contribute to mortality and morbidity in road traffic crashes in MTV drivers in Indian cities.     

Traffic speeds associated with implementation of 80 mph speed limits on West Texas rural interstates

Problem

In 2006 Texas raised the daytime speed limit for passenger vehicles on segments of I-10 and I-20 from 75 to 80 mph. Methods: Traffic speeds were measured before and 3, 12, and 16 months after the limit was changed. Results: During the 16-month period following the speed limit increase, mean speeds of passenger vehicles on I-20 increased by 9 mph relative to the comparison road, where no speed limit change occurred and traffic speeds declined. On I-10 mean speeds increased by 4 mph relative to the comparison road. Limiting the analysis to the month before the speed limit change and 1 year later, the proportion of drivers exceeding 80 mph was 18 times higher on I-20 and 2 times higher on I-10. Discussion: The smaller speed increases on I-10 may be related to its proximity to the U.S. border with Mexico. Highly visible border patrol activity coincided with posting of the higher speed limit. Long-term monitoring in other states suggests that traffic speeds in Texas are likely to continue to increase. Impact on Industry: The present study adds to the wealth of evidence that increased speed limits lead to increased travel speeds. The primary countermeasures to reduce the risk of speed-related crashes include highly visible police traffic enforcement and the use of speed cameras accompanied by publicity.     

Adaptive response criteria in road hazard detection among older drivers

Objectives: The majority of existing investigations on attention, aging, and driving have focused on the negative impacts of age-related declines in attention on hazard detection and driver performance. However, driving skills and behavioral compensation may accommodate for the negative effects that age-related attentional decline places on driving performance. In this study, we examined an important question that had been largely neglected in the literature linking attention, aging, and driving: can top-down factors such as behavioral compensation, specifically adaptive response criteria, accommodate the negative impacts from age-related attention declines on hazard detection during driving?

Methods: In the experiment, we used the Drive Aware Task, a task combining the driving context with well-controlled laboratory procedures measuring attention. We compared younger (n = 16, age 21–30) and older (n = 21, age 65–79) drivers on their attentional processing of hazards in driving scenes, indexed by percentage of correct responses and reaction time of hazard detection, as well as sensitivity and response criteria using signal detection analysis.

Results: Older drivers, in general, were less accurate and slower on the task than younger drivers. However, results from this experiment revealed that older, but not younger, drivers adapted their response criteria when the traffic condition changed in the driving scenes. When there was more traffic in the driving scene, older drivers became more liberal in their responses, meaning that they were more likely to report that a driving hazard was detected.

Conclusions: Older drivers adopt compensatory strategies for hazard detection during driving. Our findings showed that, in the driving context, even at an older age our attentional functions are still adaptive according to environmental conditions. This leads to considerations on potential training methods to promote adaptive strategies that may help older drivers maintain performance in road hazard detection.     

Assessing the impacts of signal coordination on the crash risks of various driving cohorts

Introduction: Signal coordination has been wildly implemented on urban arterials to improve traffic efficiency. The impacts of signal coordination on traffic safety, however, are largely overlooked, particularly on crash propensities of driver–vehicle cohorts, which will vary due to changing traffic flow patterns. Method: The paper aims to compare crash risks of various driving cohorts (measured by relative crash involvement ratio) on arterials with and without signal coordination with quasi-induced exposure technique, which has been well developed in estimating crash risks for driver–vehicle characteristics (i.e., driver age, gender, and vehicle type). Michigan traffic crash data (2000–2014) are retrieved for the case study. Results: The results indicate that: (a) when signal coordination is implemented, young, male drivers, and pickups are associated with more crash responsibilities; (b) crash propensities vary for different disaggregated situations, e.g., young drivers may experience the rapid increase in crash risks during the peak hours; and (c) more hazardous actions (e.g., failing to stop in assured clear distance) are witnessed for the high-risk driving cohorts on the coordinated arterials than non-coordinated ones. Conclusions and practical applications: The findings highlight the importance of safety impact analysis of signal coordination, and serve to guide the potential improvements of safety operation and management of signal coordinated arterials.     

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.     

从安全角度设计车险条款的探讨

为了使驾驶者安全驾驶,达到减少交通事故和降低保险公司理赔支出的目的,笔者的研究课题是从安全角度出发,通过条款细分的方法讨论了安全驾驶与保费厘定之间的关系,确立了“以人为本”、“从车原则”的车险条款厘定细分原则。通过分析人的性别、年龄、驾龄、驾驶记录因素、车的安全性能和使用方式等因素对安全驾驶的影响,可以得出以下结论:适当减少安全驾车者的投保费用,增加风险大的驾驶者和投保车辆的投保费用,这样可以做到以防为主,减少交通事故发生,发挥保险对交通危险的调控作用,也有利于整治保险行业的违规行为,实现车险市场的公开、公平、公正的竞争态势。     

冰雪道路环境对驾驶人视觉感知特性的影响

为预防冰雪道路环境中驾驶人因视觉感知错误引发交通事故,研究了冰雪道路环境对驾驶人视觉感知特性的影响,选择8名熟练驾驶人作为试验样本,且每2人一组,采用跟车调查的方法采集驾驶人对于自身感知车速和前导车车距的视觉感知信息,并利用非接触车速仪检测2辆跟驰行驶试验车的实际车速与车距,对冰雪条件与非冰雪条件下驾驶人的视觉感知信息进行分析对比。研究结果表明,在冰雪环境中驾驶人视觉感知车速比非冰雪环境中低5%～14%;但当2辆跟驰车辆前后车间距在50 m内时,驾驶人在冰雪环境与在非冰雪环境中行驶时,其视觉感知的车距无显著性差异。     

Emotions drive attention: Effects on driver’s behaviour

Music is the favourite activity while driving. However, very few studies have investigated its impact on driving performances. This study was designed to assess the effect of music’s emotional valence on driving behaviour. Happy, sad and neutral music excerpts were alternated with no-music phases while driving in a simulator. Results showed that happy music distracted drivers the most as their mean speed unexpectedly decreased and their lateral control deteriorated. Sad music influenced drivers in a different way as they drove slowly and kept their vehicle in its lane. These findings were discussed within the framework of attentional orienting and emotions.     

驾驶人视觉注意力需求与驾驶行为特性的关系

采用驾驶模拟系统平台,以不同车道类型及不同交通流状态(自由流/稳定流/不稳定流/强制流)为虚拟试验场,应用心理试验设计方法,测试得到21名被试在不同交通流状态下的视觉注意力需求及驾驶行为。对5种车道类型及4种交通流状态下被试驾驶时的视觉注意力需求特性和驾驶行为特性数据进行分析,得到不同车道不同交通流状态下的视觉注意力需求变化情况。利用多元回归方法分析了不同交通流状态下驾驶人视觉注意力需求与驾驶行为之间的关系,并构建了基于驾驶行为特性的驾驶人视觉注意力需求预测模型。结果表明,驾驶人视觉注意力需求与制动次数、油门踏板位移和车辆轨迹偏差之间存在相关关系。     

Driver speed selection and crash risk: Insights from the naturalistic driving study

IntroductionThis study investigates how speed limits affect driver speed selection, as well as the related crash risk, while controlling for various confounding factors such as traffic volumes and roadway geometry. Data from a naturalistic driving study are used to examine how driver speed selection varies among freeways with different posted speed limits, as well as how the likelihood of crash/near-crash events change with respect to mean speed and standard deviation.MethodRegression models are estimated to assess three measures of interest: the average speed of vehicles during the time preceding crash/near-crash and baseline (i.e., normal) driving events; the variation in travel speeds leading up to each event as quantified by the standard deviation in speeds over this period; and the probability of a specific event resulting in a crash/near-crash based on speed selection and other factors.ResultsSpeeds were relatively stable across levels-of-service A and B, within a range of 1.5 mph on average. Speeds were marginally lower (3.3 mph) on freeways posted at 65 mph versus 70 mph. In comparison, speeds were approximately 10.2 to 13.4 mph lower on facilities posted at 55 mph or 60 mph. Speeds were shown to be 2.5 mph lower in rainy weather and 11 mph lower under snow or sleet.ConclusionsSignificant correlation was observed with respect to speed selection behavior among the same individuals. Mean speeds are shown to increase with speed limits. However, these increases are less pronounced at higher speed limits. Drivers tend to reduce their travel speeds in presence of junctions and work zones, under adverse weather conditions, and particularly under heavy congestion. Crash risk increased with the standard deviation in speed, as well as on vertical curves and ramp junctions, and among the youngest and oldest age groups of drivers.     

高速公路货车事故成因及货车专用道分析

为减少货车对行车安全的影响,在充分考虑货车行驶理论、交通环境和驾驶员特征的基础上,就载重货车交通对高速公路运营安全的影响进行研究。其结果表明,不同车型之间的运行速度差异、超载、驾驶员不良交通行为及纵向间距不足等是造成货车交通事故的主要原因。通过分析货车事故与交通状况的关系,从工程技术可行性等角度提出了货车专用道的设计方法,以有效执行客货分行,提高高速公路运营安全水平。     

Society's aggression level as a predictor of traffic fatality rate

This research investigated the relationship of violence/aggression and other societal variables to traffic accidents. In the first of two studies, multiple regression was applied to 1977 data from each of the 50 states and the District of Columbia. Traffic fatalities per registered vehicle was the dependent variable. The independent variables were homicide rate, suicide rate, fatality rate from other causes, unemployment rate, personal income, density of physicians, alcohol consumption, motor vehicles per capita, road mileage per vehicle, sex and age distribution of drivers, and attained education. The main finding was that the homicide rate (but not the suicide rate) predicted the traffic fatality rate; additional significant predictors were the proportion of young drivers and the fatality rate from non-motor-vehicle accidents. The two primary predictors (homicides and young drivers) accounted for 64 % of the variance of traffic fatalities. In the second study, validation was performed by using the 1977 regression coefficients to estimate 1978 traffic fatalities. The results indicate that when the 1977 regression coefficients were applied to the 1978 values for homicides and young drivers, they accounted for 49 % of the variance of the 1978 traffic fatalities. The findings are discussed in terms of how society's violence/aggression may contribute to traffic accidents.     

The effects of driver factors and sign design features on the comprehensibility of traffic signs

PROBLEM: This paper addresses the effects of driver factors and sign design features on the comprehensibility of traffic signs. METHODS: A survey was designed to capture subjects' personal particulars, ratings on sign features, and comprehension scores, and then administered to 109 Hong Kong full driving license holders. RESULTS: Years with driving license and education level were significant predictors of sign comprehensibility. Contrary to expectation, the driver factors of age group, years of active driving, hours of driving, last time driving, driving frequency, and non-local driving experience had no effect on comprehension performance. Sign familiarity was correlated with comprehension score for licensed drivers, whereas sign concreteness, simplicity, and meaningfulness were not. IMPACT ON INDUSTRY: The results of this study provide useful guidelines for designing more user-friendly traffic signs in the future. It identified particular driver groups who lacked good understanding of traffic signs, and this information may assist the relevant organizations to better allocate traffic training resources, and better target future studies of traffic sign comprehension.