According to the study made by United Nation Economic Commission for Africa, Ethiopia stands as one of the worst countries with respect to road safety performance in terms of traffic accident fatalities per 10,000 veh...According to the study made by United Nation Economic Commission for Africa, Ethiopia stands as one of the worst countries with respect to road safety performance in terms of traffic accident fatalities per 10,000 vehicles (i.e. 95 in 2007/8). Road safety generally depends on humans, vehicles, and highway conditions. These factors influence road safety separately or in combination. One of the basic means to improve road safety is to reduce hazardous conditions of roads. The main objective of this study is to identify and rank hazardous locations and propose appropriate simple and inexpensive countermeasures along Hawassa-Shashemene-Bulbula main two-lane rural road. Accordingly, the road and traffic data were collected from field investigation and Ethiopian Road Authority and accident data were gathered from police stations. Then, the study road equally divided into short sections of 1.5 km and traffic volume and accident frequencies assigned for each road site to predict theoretical frequencies of accident. Empirical Bayes method and Safety Performance Function have been used to estimate an index known as Potential for Safety Improvement (PSI) for each site of the study area to identify and rank road sites. The result showed that out of 43 road segments 22 of them were identified as dangerous road segments. Moreover, based on further criterion established for screening the ranked road sections 8 road segments were found the most dangerous road segments as they have contributed 76% of total PSI values. The degree of haphazardness of a given road segment in the study area has directly associated with the availability of risk indicating road and traffic factors. Finally, it recommends that regulatory body of road safety in the study area should give high priority and immediate response for the improvement of most dangerous road segments.展开更多
In recent years,advancements in autonomous vehicle technology have accelerated,promising safer and more efficient transportation systems.However,achieving fully autonomous driving in challenging weather conditions,par...In recent years,advancements in autonomous vehicle technology have accelerated,promising safer and more efficient transportation systems.However,achieving fully autonomous driving in challenging weather conditions,particularly in snowy environments,remains a challenge.Snow-covered roads introduce unpredictable surface conditions,occlusions,and reduced visibility,that require robust and adaptive path detection algorithms.This paper presents an enhanced road detection framework for snowy environments,leveraging Simple Framework forContrastive Learning of Visual Representations(SimCLR)for Self-Supervised pretraining,hyperparameter optimization,and uncertainty-aware object detection to improve the performance of YouOnly Look Once version 8(YOLOv8).Themodel is trained and evaluated on a custom-built dataset collected from snowy roads in Tromsø,Norway,which covers a range of snow textures,illumination conditions,and road geometries.The proposed framework achieves scores in terms of mAP@50 equal to 99%and mAP@50–95 equal to 97%,demonstrating the effectiveness of YOLOv8 for real-time road detection in extreme winter conditions.The findings contribute to the safe and reliable deployment of autonomous vehicles in Arctic environments,enabling robust decision-making in hazardous weather conditions.This research lays the groundwork for more resilient perceptionmodels in self-driving systems,paving the way for the future development of intelligent and adaptive transportation networks.展开更多
Vehicle operating speed is a crucial factor for road safety,as it strictly affects occurrence and severity of crashes.Usually,85th percentile of the operating speed distributions(i.e.,V85)in free-flow traffic conditio...Vehicle operating speed is a crucial factor for road safety,as it strictly affects occurrence and severity of crashes.Usually,85th percentile of the operating speed distributions(i.e.,V85)in free-flow traffic condition is widely accepted as a base value of consistency evaluation for homogenous portion of existing roads.Although the computation of V85 is simple,many road authorities cannot collect speed data for each road.Therefore,providing prediction models could be a useful tool to investigate the relationship between V85 and road characteristics.The literature proposed several models to account it.However,to the best of our knowledge,the effects of some road geometric characteristics,road markings and signs,traffic data,type of terrain and the simultaneous consideration of different road categories on the V85 prediction were not completely analyzed.This paper fills this gap by isolating key variables that mostly affect V85.In doing so,60000+car spot speed data were collected along the county road network of the province of Brescia(Italy),and then processed by multiple regression models.The main findings show that V85 increases owing to the presence of a wider or paved shoulder,visible road median markings,a higher number of lanes and a higher percentage of cars with respect to the total traffic flow.Conversely,V85 decreases as the road axis curvature,the number of accesses and rate of forbidden overtaking increase.In addition,the presence of visible road external markings and the surrounding mountainous terrain contribute to decreasing V85.The overall findings may support road authorities to verify roads’operating conditions and,possibly,adjust the speed limits,especially for existing roads.展开更多
Roads are one of the most important infrastructures in any country. One problem on road based transportation networks is accident. Current methods to identify of high potential segments of roads for accidents are base...Roads are one of the most important infrastructures in any country. One problem on road based transportation networks is accident. Current methods to identify of high potential segments of roads for accidents are based on statistical approaches that need statistical data of accident occurrences over an extended period of time so this cannot be applied to newly-built roads. In this research a new approach for road hazardous segment identification (RHSI) is introduced using Geospatial Information System (GIS) and fuzzy reasoning. In this research among all factors that usually play critical roles in the occurrence of traffic accidents, environmental factors and roadway design are considered. Using incomplete data the consideration of uncertainty is herein investigated using fuzzy reasoning. This method is performed in part of Iran's transit roads (Kohin-Loshan) for less expensive means of analyzing the risks and road safety in Iran. Comparing the results of this approach with existing statistical methods shows advantages when data are uncertain and incomplete, specially for recently built transportation roadways where statistical data are limited. Results show in some instances accident locations are somewhat displaced from the segments of highest risk and in few sites hazardous segments are not determined using traditional statistical methods.展开更多
The development of autonomous vehicles has become one of the greatest research endeavors in recent years. These vehicles rely on many complex systems working in tandem to make decisions. For practical use and safety r...The development of autonomous vehicles has become one of the greatest research endeavors in recent years. These vehicles rely on many complex systems working in tandem to make decisions. For practical use and safety reasons, these systems must not only be accurate, but also quickly detect changes in the surrounding environment. In autonomous vehicle research, the environment perception system is one of the key components of development. Environment perception systems allow the vehicle to understand its surroundings. This is done by using cameras, light detection and ranging (LiDAR), with other sensor systems and modalities. Deep learning computer vision algorithms have been shown to be the strongest tool for translating camera data into accurate and safe traversability decisions regarding the environment surrounding a vehicle. In order for a vehicle to safely traverse an area in real time, these computer vision algorithms must be accurate and have low latency. While much research has studied autonomous driving for traversing well-structured urban environments, limited research exists evaluating perception system improvements in off-road settings. This research aims to investigate the adaptability of several existing deep-learning architectures for semantic segmentation in off-road environments. Previous studies of two Convolutional Neural Network (CNN) architectures are included for comparison with new evaluation of Vision Transformer (ViT) architectures for semantic segmentation. Our results demonstrate viability of ViT architectures for off-road perception systems, having a strong segmentation accuracy, lower inference speed and memory footprint compared to previous results with CNN architectures.展开更多
为提升随机路面与局部脉冲激励路面下的悬架平顺性,提出语义分割路面识别的主动悬架显式模型预测控制(Explicit Model Predict Control,EMPC)方法。建立2自由度主动悬架动力学模型;搭建基于空洞空间金字塔池化的DeepLabV3语义分割路面...为提升随机路面与局部脉冲激励路面下的悬架平顺性,提出语义分割路面识别的主动悬架显式模型预测控制(Explicit Model Predict Control,EMPC)方法。建立2自由度主动悬架动力学模型;搭建基于空洞空间金字塔池化的DeepLabV3语义分割路面识别网络,对网络进行训练及验证;设计基于路面识别的主动悬架EMPC控制策略,将悬架动力学模型转化为预测模型,确定代价函数和约束条件,根据路面识别结果匹配代价函数最优加权权重;离线划分系统状态参数区域,求解各状态分区内系统的最优控制律;在随机路面和脉冲路面下,将所设计的控制策略与被动悬架、线性二次高斯控制(Linear-quadratic-gaussian Control,LQG)进行仿真分析对比。相较于LQG控制,基于路面识别的主动悬架EMPC控制策略可在随机路面下改善悬架性能,且在脉冲路面下对悬架的调节时间降低20%以上,悬架的平顺性得到有效提升。展开更多
文摘According to the study made by United Nation Economic Commission for Africa, Ethiopia stands as one of the worst countries with respect to road safety performance in terms of traffic accident fatalities per 10,000 vehicles (i.e. 95 in 2007/8). Road safety generally depends on humans, vehicles, and highway conditions. These factors influence road safety separately or in combination. One of the basic means to improve road safety is to reduce hazardous conditions of roads. The main objective of this study is to identify and rank hazardous locations and propose appropriate simple and inexpensive countermeasures along Hawassa-Shashemene-Bulbula main two-lane rural road. Accordingly, the road and traffic data were collected from field investigation and Ethiopian Road Authority and accident data were gathered from police stations. Then, the study road equally divided into short sections of 1.5 km and traffic volume and accident frequencies assigned for each road site to predict theoretical frequencies of accident. Empirical Bayes method and Safety Performance Function have been used to estimate an index known as Potential for Safety Improvement (PSI) for each site of the study area to identify and rank road sites. The result showed that out of 43 road segments 22 of them were identified as dangerous road segments. Moreover, based on further criterion established for screening the ranked road sections 8 road segments were found the most dangerous road segments as they have contributed 76% of total PSI values. The degree of haphazardness of a given road segment in the study area has directly associated with the availability of risk indicating road and traffic factors. Finally, it recommends that regulatory body of road safety in the study area should give high priority and immediate response for the improvement of most dangerous road segments.
文摘In recent years,advancements in autonomous vehicle technology have accelerated,promising safer and more efficient transportation systems.However,achieving fully autonomous driving in challenging weather conditions,particularly in snowy environments,remains a challenge.Snow-covered roads introduce unpredictable surface conditions,occlusions,and reduced visibility,that require robust and adaptive path detection algorithms.This paper presents an enhanced road detection framework for snowy environments,leveraging Simple Framework forContrastive Learning of Visual Representations(SimCLR)for Self-Supervised pretraining,hyperparameter optimization,and uncertainty-aware object detection to improve the performance of YouOnly Look Once version 8(YOLOv8).Themodel is trained and evaluated on a custom-built dataset collected from snowy roads in Tromsø,Norway,which covers a range of snow textures,illumination conditions,and road geometries.The proposed framework achieves scores in terms of mAP@50 equal to 99%and mAP@50–95 equal to 97%,demonstrating the effectiveness of YOLOv8 for real-time road detection in extreme winter conditions.The findings contribute to the safe and reliable deployment of autonomous vehicles in Arctic environments,enabling robust decision-making in hazardous weather conditions.This research lays the groundwork for more resilient perceptionmodels in self-driving systems,paving the way for the future development of intelligent and adaptive transportation networks.
基金the research agreement research agreement signed in 2019 by the University of Brescia and the Province of Brescia(Prot.668/2019).
文摘Vehicle operating speed is a crucial factor for road safety,as it strictly affects occurrence and severity of crashes.Usually,85th percentile of the operating speed distributions(i.e.,V85)in free-flow traffic condition is widely accepted as a base value of consistency evaluation for homogenous portion of existing roads.Although the computation of V85 is simple,many road authorities cannot collect speed data for each road.Therefore,providing prediction models could be a useful tool to investigate the relationship between V85 and road characteristics.The literature proposed several models to account it.However,to the best of our knowledge,the effects of some road geometric characteristics,road markings and signs,traffic data,type of terrain and the simultaneous consideration of different road categories on the V85 prediction were not completely analyzed.This paper fills this gap by isolating key variables that mostly affect V85.In doing so,60000+car spot speed data were collected along the county road network of the province of Brescia(Italy),and then processed by multiple regression models.The main findings show that V85 increases owing to the presence of a wider or paved shoulder,visible road median markings,a higher number of lanes and a higher percentage of cars with respect to the total traffic flow.Conversely,V85 decreases as the road axis curvature,the number of accesses and rate of forbidden overtaking increase.In addition,the presence of visible road external markings and the surrounding mountainous terrain contribute to decreasing V85.The overall findings may support road authorities to verify roads’operating conditions and,possibly,adjust the speed limits,especially for existing roads.
文摘Roads are one of the most important infrastructures in any country. One problem on road based transportation networks is accident. Current methods to identify of high potential segments of roads for accidents are based on statistical approaches that need statistical data of accident occurrences over an extended period of time so this cannot be applied to newly-built roads. In this research a new approach for road hazardous segment identification (RHSI) is introduced using Geospatial Information System (GIS) and fuzzy reasoning. In this research among all factors that usually play critical roles in the occurrence of traffic accidents, environmental factors and roadway design are considered. Using incomplete data the consideration of uncertainty is herein investigated using fuzzy reasoning. This method is performed in part of Iran's transit roads (Kohin-Loshan) for less expensive means of analyzing the risks and road safety in Iran. Comparing the results of this approach with existing statistical methods shows advantages when data are uncertain and incomplete, specially for recently built transportation roadways where statistical data are limited. Results show in some instances accident locations are somewhat displaced from the segments of highest risk and in few sites hazardous segments are not determined using traditional statistical methods.
文摘The development of autonomous vehicles has become one of the greatest research endeavors in recent years. These vehicles rely on many complex systems working in tandem to make decisions. For practical use and safety reasons, these systems must not only be accurate, but also quickly detect changes in the surrounding environment. In autonomous vehicle research, the environment perception system is one of the key components of development. Environment perception systems allow the vehicle to understand its surroundings. This is done by using cameras, light detection and ranging (LiDAR), with other sensor systems and modalities. Deep learning computer vision algorithms have been shown to be the strongest tool for translating camera data into accurate and safe traversability decisions regarding the environment surrounding a vehicle. In order for a vehicle to safely traverse an area in real time, these computer vision algorithms must be accurate and have low latency. While much research has studied autonomous driving for traversing well-structured urban environments, limited research exists evaluating perception system improvements in off-road settings. This research aims to investigate the adaptability of several existing deep-learning architectures for semantic segmentation in off-road environments. Previous studies of two Convolutional Neural Network (CNN) architectures are included for comparison with new evaluation of Vision Transformer (ViT) architectures for semantic segmentation. Our results demonstrate viability of ViT architectures for off-road perception systems, having a strong segmentation accuracy, lower inference speed and memory footprint compared to previous results with CNN architectures.
文摘为提升随机路面与局部脉冲激励路面下的悬架平顺性,提出语义分割路面识别的主动悬架显式模型预测控制(Explicit Model Predict Control,EMPC)方法。建立2自由度主动悬架动力学模型;搭建基于空洞空间金字塔池化的DeepLabV3语义分割路面识别网络,对网络进行训练及验证;设计基于路面识别的主动悬架EMPC控制策略,将悬架动力学模型转化为预测模型,确定代价函数和约束条件,根据路面识别结果匹配代价函数最优加权权重;离线划分系统状态参数区域,求解各状态分区内系统的最优控制律;在随机路面和脉冲路面下,将所设计的控制策略与被动悬架、线性二次高斯控制(Linear-quadratic-gaussian Control,LQG)进行仿真分析对比。相较于LQG控制,基于路面识别的主动悬架EMPC控制策略可在随机路面下改善悬架性能,且在脉冲路面下对悬架的调节时间降低20%以上,悬架的平顺性得到有效提升。
