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Road accidents have always been one of the important reasons for fatalities and financial losses. Since road accidents on rural highways cause more serious injuries than those on urban highways, providing a suitable method to increase safety in the curves can be a significant contributor to preventing these damages. Although speed is one of the most important variables affecting highway safety, numerous studies have been performed on the reliability analysis of horizontal curves without taking the speed variable into account. The aim of this research is reliability (probability of noncompliance) assessment in the horizontal curve design using geometric design consistency criteria. The radius, superelevation, and operating speed of 19 horizontal curves were collected by field research on the Mashhad-Torbat Heydarieh highway in Iran. Three different approaches were defined based on the geometric design consistency criterion of a single horizontal curve, and consecutively, the probability of noncompliance was calculated using these approaches. According to the obtained results, this study showed that radius enhancement increases the probability of noncompliance and the consistency level of the geometric design. Finally, the high values of the probability of noncompliance (failure) indicate that the geometric design guidelines need calibration in the design of horizontal curves, especially for higher radii., Author(s): Hossein Saedi (corresponding author) [1]; Ali Abdi Kordani [1]; Seyed Mohsen Hosseinian [1] 1. Introduction Road accident is one of the important reasons for death in human societies [1, [...]

Crashes on a roadway are influenced by various factors, including but not limited to road geometries, traffic volume, and environmental conditions. Among these factors, traffic volume and segment length are commonly used to predict crashes. Recently, the role of speed in crashes has been recognized as a significant factor, prompting its incorporation as a variable in crash modeling. Nevertheless, previous research studies that examined speed-related factors are mostly concentrated on higher functional class roads where speed data are abundant. Lack of actual speed data has limited the scope of such a study on rural two-lane highways. Due to recent advancements in data collection methodologies, there has been a significant increase in the accessibility of speed data pertaining to these roads. This study aims to assess the significance of speed as a predictor of crashes on rural two-lane highways, utilizing actual speed data. The results of this study showed a negative correlation between speed and crash frequency on rural two-lane roadways. In addition, it was observed that the impact of speed in the crash model becomes more pronounced at higher operating speed conditions of these roads. The aforementioned observation prompted us to consider a categorizer based on speed and, afterwards, separating crash prediction models for various speed ranges. This approach ultimately resulted in enhanced accuracy in crash prediction. Based on our analysis, developing separate models at different speed levels is recommended to better evaluate the safety performance of these roads under various conditions. Such models can also be useful for transportation planners and policymakers to identify high-risk segments and allocate resources to improve the safety of these roads., Author(s): Fahmida Rahman (corresponding author) [1]; Xu Zhang [2]; Mei Chen [3] 1. Background According to a study conducted in the United States, rural two-lane highways account for a significant [...]

Civil aviation transportation equipment is more convenient and faster than other transportation tools and is an essential part of intelligent transportation. It is significant to study the reliability of positioning information and enhance traffic safety. Advanced receiver autonomous integrity monitoring (ARAIM) can provide vertical guidance during the different navigation stages in civil aviation fields. The traditional multiple hypothesis solution separation (MHSS) algorithm distributes the probability of hazardous misleading information (PHMI) and probability of false alarm (PFA) uniformly over all visible satellites resulting in reduced global availability of ARAIM. Aiming at this problem, we proposed an adaptive simulated annealing particle swarm optimization (ASAPSO) algorithm to redistribute integrity and continuity risks and establish a protection level optimization model. Based on the real BeiDou navigation satellite system/global positioning system (BDS/GPS) data, the experimental results show that the optimized algorithm can reduce the vertical protection level (VPL), and the ARAIM global availability of BDS/GPS is improved by 1.73%∼2.73%. The optimized algorithm can improve the availability of integrity monitoring at different stages of the navigation system and provide a basis for ensuring the reliability of the positioning results., Author(s): Ershen Wang [1,2]; Xiaozhu Shi [1,3]; Xidan Deng [2]; Jing Gao (corresponding author) [4]; Wei Zhang [1,3]; Huan Wang [2]; Song Xu [2] 1. Introduction The BDS-3 satellite navigation [...]

This article aims to explore an effective method for reducing vehicle collisions at unsignalized intersections. First, a monocular-binocular vision switching system is built to enable machine vision-based detection of obstacle vehicles in the left and right front directions. Then, the motion state and trajectory of each obstacle vehicle are predicted, and the intersection points of the trajectories of the obstacle vehicle and the ego vehicle are calculated. On this basis, a cross-conflict judgment model based on trajectories and collision times and a safety assessment model based on safety distance are established. Finally, the conflict judgment and safety assessment for the obstacle vehicles are simulated. The results of the simulation demonstrate that the monocular-binocular vision switching system proposed in this article can achieve a detection accuracy of 95%, a ranging accuracy of 96%, and a cross-conflict detection accuracy of 97%, while ensuring a maximum detection area, which can meet the requirements of traffic safety assurance at unsignalized intersections., Author(s): Yuqiong Wang [1]; Liming Wang [1]; Ruoyu Zhu [1]; Yi Xu (corresponding author) [1,2]; Guoxin Jiang [1]; Xiaotian Ma [3] 1. Introduction Traffic conflict can be expressed as the [...]

In the past several years, an array of technologists, economists, and technology pundits have predicted that advances in artificial intelligence (AI) are poised to revolutionize our lives, changing how we [...]

Understanding the factors contributing to crash severity, along with their influence degrees across different times of day, can assist in better highway design and in developing effective countermeasures for ameliorating highway safety (especially during nighttime). This study examines the influences of risk factors on crash severity, based on comparisons of nighttime and daytime crashes. By using a random parameter approach to account for unobserved heterogeneity, multivariate logit (RPML) models are proposed to analyze the crash severity based on the explanatory factors in terms of the crash, traffic, speed, road geometry, and sight characteristics. The goodness-of-fit and predictive measures highlight the better performance of the proposed models relative to standard models, as the proposed models reduce the unobserved heterogeneity and yield higher precision. In addition, the elasticity effects of the factors are calculated to investigate and compare their impact degrees in daytime and nighttime crashes. The findings could potentially be utilized to guide highway design and policies and to develop specific safety countermeasures., Author(s): Chenzhu Wang [1]; Ping Zhang [2]; Fei Chen (corresponding author) [1]; Jianchuan Cheng [1] 1. Introduction In 2015, the World Health Organization reported 217711 deaths in traffic crashes in [...]

Abstract. Usage-based insurance (UBI) is a recent auto insurance innovation that enables insurers to collect individual-level driving data, provide feedback on driving performance, and offer individually targeted price discounts based [...]

Some observers tout autonomous (self-driving) vehicles by claiming that a computer is 'simply a better driver than a human,' as a recent Time magazine article put it. This is not [...]

Road transport is the dominant mode of transport in Pakistan carrying 91% of the country's passenger traffic and 96% of freight traffic. National highways, being 3.7% of the entire road network, carry 80% of commercial traffic. Due to the high number of road traffic crashes and resulting fatalities, a random parameters logit model was estimated to determine the risk factors that influence the severity of injuries caused by motor vehicle crashes on national highways. The effects of driver characteristics, crash characteristics, highway characteristics, temporal characteristics, and environmental characteristics were considered for the analysis. From the results, it was revealed that many factors such as overspeeding, driver dozing, driver carelessness, driver age, Author(s): Hanif Ullah (corresponding author) [1]; Asim Farooq [1]; Akhtar Ali Shah [2] 1. Introduction Globally, around 1.35 million human lives are lost due to road traffic crashes (RTCs) every [...]

Variable speed limit (VSL) control dynamically adjusts the displayed speed limit to harmonize traffic speed, prevent congestions, and reduce crash risks based on prevailing traffic stream and weather conditions. Previous research studies examine the impacts of VSL control on reducing corridor-level crash risks and improving bottleneck throughput. However, less attention focuses on utilizing real-world data to see how compliant the drivers are under different VSL values and how the aggregated driving behavior changes. This study aims to fill the gap. With the high-resolution lane-by-lane traffic big data collected from a European motorway, this study performs statistical analysis to measure the difference in driving behavior under different VSL values and analyze the safety impacts of VSL controls on aggregate driving behaviors (mean speed, average speed difference, and the percentage of small space headway). The data analytics show that VSL control can effectively decrease the mean speed, the speed difference, and the percentage of small space headways. The safety impacts of VSL control on aggregated driving behavior are also discussed. The aggregated driving behavior variables follow a trend of first decreasing and then increasing with the continuous decrease in VSL values, indicating that potential traffic safety benefits can be achieved by adopting suitable VSL values that match with prevailing traffic conditions., Author(s): Xu Qu (corresponding author) [1,2]; Mofeng Yang [3]; Junyi Ji [1]; Linheng Li [1,2]; Bin Ran [1,2,4] 1. Introduction Variable speed limit (VSL) control dynamically adjusts the displayed speed [...]

Unpredictable and heterogeneous weather conditions and road incidents are common factors that impact highway traffic speeds. A better understanding of the interplay of different factors that affect roadway traffic speeds is essential for policymakers to mitigate congestion and improve road safety. This study investigates the effect of precipitation and incidents on the speed of traffic in the eastbound direction of I-64 in Virginia. To the best of our knowledge, this is the first study that studies the relationship between precipitation and incidents as factors that would have a combined effect on traffic stream speeds. Furthermore, using a mixture model of two linear regressions, we were able to model the two different regimes that the traffic speed could be classified into, namely, free-flow and congested. Using INRIX traffic data from 2013 through 2016 along a 25.6-mi section of Interstate 64 in Virginia, results show that the reduction of traffic speed only due to incidents ranges from 41% to 75% if the road is already congested. In this case, precipitation was found to be statistically insignificant. However, regardless of the incident impact, the effect of light rain in free-flow conditions ranges from insignificant to a 4% speed reduction while the effect of heavy rain ranges from a 0.6% to a 6.5% speed reduction when the incident severity is low but has a roughly double effect when the incident severity is high., Author(s): Mohammed Elhenawy [1]; Hesham A. Rakha (corresponding author) [2]; Huthaifa I. Ashqar [3] 1. Introduction Unclear weather conditions and incidents are common factors that impact traffic speed. While weather [...]

Variable speed limit (VSL) control dynamically adjusts the displayed speed limit to harmonize traffic speed, prevent congestions, and reduce crash risks based on prevailing traffic stream and weather conditions. Previous research studies examine the impacts of VSL control on reducing corridor-level crash risks and improving bottleneck throughput. However, less attention focuses on utilizing real-world data to see how compliant the drivers are under different VSL values and how the aggregated driving behavior changes. This study aims to fill the gap. With the high-resolution lane-by-lane traffic big data collected from a European motorway, this study performs statistical analysis to measure the difference in driving behavior under different VSL values and analyze the safety impacts of VSL controls on aggregate driving behaviors (mean speed, average speed difference, and the percentage of small space headway). The data analytics show that VSL control can effectively decrease the mean speed, the speed difference, and the percentage of small space headways. The safety impacts of VSL control on aggregated driving behavior are also discussed. The aggregated driving behavior variables follow a trend of first decreasing and then increasing with the continuous decrease in VSL values, indicating that potential traffic safety benefits can be achieved by adopting suitable VSL values that match with prevailing traffic conditions., Author(s): Xu Qu (corresponding author) [1,2]; Mofeng Yang [3]; Junyi Ji [1]; Linheng Li [1,2]; Bin Ran [1,2,4] 1. Introduction Variable speed limit (VSL) control dynamically adjusts the displayed speed [...]

Road transport is the dominant mode of transport in Pakistan carrying 91% of the country's passenger traffic and 96% of freight traffic. National highways, being 3.7% of the entire road network, carry 80% of commercial traffic. Due to the high number of road traffic crashes and resulting fatalities, a random parameters logit model was estimated to determine the risk factors that influence the severity of injuries caused by motor vehicle crashes on national highways. The effects of driver characteristics, crash characteristics, highway characteristics, temporal characteristics, and environmental characteristics were considered for the analysis. From the results, it was revealed that many factors such as overspeeding, driver dozing, driver carelessness, driver age, Author(s): Hanif Ullah (corresponding author) [1]; Asim Farooq [1]; Akhtar Ali Shah [2] 1. Introduction Globally, around 1.35 million human lives are lost due to road traffic crashes (RTCs) every [...]

Unpredictable and heterogeneous weather conditions and road incidents are common factors that impact highway traffic speeds. A better understanding of the interplay of different factors that affect roadway traffic speeds is essential for policymakers to mitigate congestion and improve road safety. This study investigates the effect of precipitation and incidents on the speed of traffic in the eastbound direction of I-64 in Virginia. To the best of our knowledge, this is the first study that studies the relationship between precipitation and incidents as factors that would have a combined effect on traffic stream speeds. Furthermore, using a mixture model of two linear regressions, we were able to model the two different regimes that the traffic speed could be classified into, namely, free-flow and congested. Using INRIX traffic data from 2013 through 2016 along a 25.6-mi section of Interstate 64 in Virginia, results show that the reduction of traffic speed only due to incidents ranges from 41% to 75% if the road is already congested. In this case, precipitation was found to be statistically insignificant. However, regardless of the incident impact, the effect of light rain in free-flow conditions ranges from insignificant to a 4% speed reduction while the effect of heavy rain ranges from a 0.6% to a 6.5% speed reduction when the incident severity is low but has a roughly double effect when the incident severity is high., Author(s): Mohammed Elhenawy [1]; Hesham A. Rakha (corresponding author) [2]; Huthaifa I. Ashqar [3] 1. Introduction Unclear weather conditions and incidents are common factors that impact traffic speed. While weather [...]