CROSSING SPEEDS OF CARS THROUGH SIGNALIZED INTERSECTIONS Galusca, Narciza-Izabela; Iriciuc, Silviu-Cristian; Gimiga, Gelu-Răzvan ...
Journal of Engineering Science (Chişinău),
11/2023, Letnik:
30, Številka:
3
Journal Article
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The article deals with the problem of traffic in three traffic-light intersections in the street network of Iasi city. Usually, the existing traffic lights do not fully take into account the size, ...structure and parameters of the queue of vehicles waiting at intersections; which in turn affects the traffic capacity of the intersection. In the study, we used a representative set of measurements taken at the three intersections to interpret the variation in the crossing speeds of the traffic light intersection space by the vehicle columns using the linear regression method. We studied several categories of vehicles queuing before the stop line at the intersection. We made a statistical analysis of the time taken to cross three intersections by vehicles in different starting positions. The main results of the research showed estimates in good agreement with observational data as well as a significant reduction in vehicle speed (to 58%) when there are different categories of vehicles queuing at the intersection. This study can be used in the urban traffic diagnosis method, being part of a traffic study together with urban traffic forecasting and therapy.
With the emergence of connected and automated vehicles (CAVs), the mixed traffic environment where conventional human-driven vehicles (HVs) share the road space with CAVs is impending. Targeted ...management of such mixed traffic flow at intersections is of practical significance, inspiring the theoretical exploration of CAVs impacts on intersection capacity in this study. Penetration rate and platooning behavior of CAVs are the major concern. Not only the three core platooning parameters (intra-platoon gap, inter-platoon gap and platoon size) are investigated, but also the individual willingness of CAVs to form platoons is innovatively considered. Intersection capacity is modeled as an objective function of a linear program problem that maximizes the sum of throughput of each stream crossing the intersection under collision-free constraints. These constraints are determined by the conflicting relationship of vehicles on different streams and the vehicle’s average occupation time of conflict points. The average occupation time is defined by adopting the service time concept in queueing theory, and specified by applying the Markov chain theory considering the spatial distribution of heterogeneous vehicle headways in mixed traffic. This study provides a practical procedure to analyze the influence of CAVs on mixed traffic at intersections, without the need to determine specific intersection management methods. Corollaries drawn are basically consistent with expectations, except that high CAV penetration does not necessarily correspond to high intersection capacity. In order for the influence of penetration to be positive, the platooning willingness must be controlled within the corresponding range, suggesting that CAV penetration rate and platooning willingness should be considered jointly when updating intersection management for mixed CAVs–HVs traffic flow. Furthermore, numerical analyses are carried out to corroborate the analytical conclusions.
•Analytical formulation for intersection capacity by integrating linear program and queueing theory is developed for mixed traffic with CAVs.•CAV penetration rate and related heterogeneous vehicle headways in mixed traffic are considered.•CAVs platooning parameters including willingness contribute to the intersection capacity.•Analytical analysis is verified by Monte Carlo simulations.
•A new procedure for assessing intervisibility between conflicting agents (IvCA)•An agent-based approach for identifying conflicting agents at intersections in real-time.•Both static infrastructure ...and dynamic agents were modeled as sight obstacles.•Assessing IvCA at each frame within 0.1 s on average with limited computational power.
A new procedure is developed for effectively monitoring intervisibility between conflicting agents in real-time at intersections. Dense light detection and ranging (Lidar) point clouds and time-stamped trajectory data are used to model static intersection environment and emulate traffic participants’ dynamic motion states, respectively. The proposed procedure reads trajectory data in sequence according to their timestamps. An agent-based approach that enables the application of multi-core parallel computing is applied to estimate conflict points and identify conflicting agents in pairs. Then, a linear elevation array is created from the Lidar point cloud data, based on which the elevation of each trajectory point is obtained in a real-time manner. Meanwhile, three-dimensional bounding cuboids are generated at each path point to represent digital twins of agents. Once a pair of conflicting agents are identified, a hybrid approach is triggered to examine whether the agents’ line-of-sights are occluded by either static (e.g., tree trunk) or dynamic obstacles (e.g., cars). Accordingly, virtual warning signals can be generated. The effectiveness of the procedure is demonstrated through controlled experiments. The procedure was also tested in two virtual scenarios. The mean processing time at each frame is less than 0.1 s as achieved with limited computational power. With implementation of parallel computing technique, processing time is not sensitive to number of agents within the intersection. In addition, by enabling the outputs of virtual warning signals, spatial distribution of conflict points, and individual conflict-related time series data, the procedure shall help provide substantial insights into intersection safety.
Public vehicles and personal navigation assistants have become increasingly equipped with single-frequency global positioning system (GPS) receivers or loggers. These commonly used terminals offer an ...inexpensive way for acquiring large volumes of GPS traces, which contain information pertaining to road position and traffic rules. Using this new type of spatial data resource, we propose a novel approach for generating high-quality routable road maps. In this approach, a simplified road network graph model uses circular boundaries to separate all GPS traces into road intersections and road segments and builds road networks that maintain their identical geometric topologies through the entry/exit points at the original boundaries. One difficulty inherent to this type of approach is how to best determine the appropriate spatial coverage for road intersections. Conflict points among GPS traces that have large intersection angles usually occur within the physical areas of road intersections, particularly those involving left turns. Therefore, we determined a proper circle boundary for individual road intersections by conducting a spatial analysis of such feature points. This approach was implemented using Python and PostgreSQL/PostGIS and was tested in Huaibei City, China. Based on a comparison with human-interpreted results, the automatically generated routable road map was demonstrated to be of high quality and displayed detailed road networks with turning at various at-grade intersections, interchanges and U-turns.
Design of urban intersections, as well as the traffic control design on them requires the development of methods of capacity, traffic delays and queues estimation. Two and three-lane roundabouts are ...designed and operated in many cities of the Russian Federation. Currently there are no approved methods of performance estimation of such multilane roundabouts. The development of such methods would require the determination of all characteristics which are used in consistent calculations of capacity, traffic delays and queue lengths. Research target is to establish the values of multilane roundabouts critical headway and follow-up time. Two-lane traffic circles are analyzed at this research stage. Video records were received from the cities of Bratsk, Petrozavodsk, Pskov. The headways measured between the front bumpers of cars, were recorded on each lane of the circular roadway. Critical headway and follow-up time were determined using linear regression. It was found that the values of critical headway and follow-up time of the left and right entry lanes have different values. These results proved the validity of capacity calculation methods based on a separate consideration of each of entry lane. Further research will focus on estimation of critical headway and follow-up time for three-lane roundabouts. Consistent solving of mentioned above research tasks will allow to form an estimation methodology for all characteristics of multilane roundabouts.
Unsignalized intersections in India are uncontrolled, and are characterized by chaotic traffic situation and have become accident hot spots. In this study, we have collected traffic data at three ...uncontrolled intersections, one each is from city center (Type I), suburb (Type II), and outskirt (Type III). Traffic parameters, such as traffic composition, speed variations, lane distribution, trajectories, conflict points, and pedestrian movements are analyzed. All the vehicle classes prefer inner lane, except auto-rickshaws. The speed on inner lane is higher than outer lane vehicles as latter are affected by the roadside friction. It is also found that the minor approach vehicles have to slow down or stop many times. Trajectories of two-wheelers are found to be much flatter than the trajectories in the standard conflict point diagram. This study has great potential in assessing the performance and safety of unsignalized intersections in developing world.
The article presents a functional block diagram of the findings of studies on the developed approach to automatic control systems (ACSs) at signalized intersections with assessment and assurance of ...compliance with the levels of traffic safety requirements. The approach uses traffic patterns with conflict loads at different methods of control over traffic signalization cycles: without a change of the scenarios in the paradigm of traditional traffic control methods I (phased traffic control) or II (traffic control by directions) and with a new method of combined traffic control III. The latter allows us to combine a change of the scenarios of traditional traffic control methods I and II in different phases of the cyclic traffic control. The change of the scenarios in phases of method III depends on the vehicle density threshold values for left-turn and right-turn flows as well as pedestrians. If these values are within the set limit and the Traffic Rules of the Russian Federation are met, traffic control method I is used, when the density threshold is not maintained, the scenario in phases changes to method II and, therefore, road traffic safety is ensured.
Vehicle fuel consumption and emission rates in Kuwait have increased considerably over recent decades, and are now causing health and economic problems. A three-lane smart roundabout is a new and ...innovative design idea that can help to mitigate these issues. The smart roundabout was designed with a dedicated exit lane on the right side of each entryway, and a U-turn path connecting each adjacent entry and exit road. Both features permit vehicles to turn in specific directions without needing to enter the roundabout itself. Underground tunnels were designed for pedestrian and cyclist use. The objective of this study was to measure the impact of a smart roundabout on vehicle fuel consumption and on emissions of carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. These results were then compared with those of a traditional roundabout and of a light-signalised intersection. Two light-signalised intersections with different traffic volumes were chosen for this study and simulated in their present state, as replaced by traditional roundabouts; and as replaced by smart roundabouts using the SIDRA 6.0 software. The smart roundabout allowed traffic to proceed with minimal delay and idling time, significantly reducing vehicle fuel consumption and emissions in comparison with a traditional roundabout or light-signalised intersection. Furthermore, the smart roundabout allowed pedestrians and cyclists to move safely through the intersection without interacting with vehicular traffic. Voertuig brandstofverbruik en emissietempo's in Koeweit het aansienlik verhoog oor die laaste paar dekades en veroorsaak gesondheid- en ekonomiese probleme. A drie-laan slim verkeersirkel is 'n nuwe en innoverende ontwerp wat kan bydrae tot die verligting van hierdie kwessies. Die slim verkeersirkel is ontwerp met 'n toegewyde uitgangslaan aan die regterkant van elke ingang en 'n U-draai baan wat naburige ingang- en uitgangslane verbind. Beide kenmerke laat voertuie toe om in spesifieke rigtings te draai sonder om die verkeersirkel te betree. Ondergrondse tonnels is gebruik vir voetgangers en fietsryers. Die doel van die studie is om die impak van so 'n slim verkeersirkel op die brandstofverbruik en uitlaat van koolstofdioksied, koolstofmonoksied, stikstofoksiede en hidrokoolstowwe te meet. Die resultate is dan met dié van 'n tradisionele verkeersirkel en 'n verkeersligkruising vergelyk. Twee verkeersligkruisings met verskillende verkeervolumes is gekies vir hierdie studie en in hul huidige toestand, met tradisionele verkeersirkels en met die voorgestelde slim verkeersirkel, met behulp van die SIDRA 6.0 sagteware gesimuleer. Die slim verkeersirkel het die verkeer met minimale vertraging en luier tyd laat vloei wat die brandstofverbruik en uitlaatgasse noemenswaardig laat verminder het. Verder het die slim verkeersirkel voetgangers en fietsryers met veilige deurgang deur die kruising verskaf sonder om met die padverkeer te meng.
This paper presents part of the research on traffic risk estimation for Bucharest City area. The aim of our research is to develop complex models as tools of urban traffic risk assessment in planning ...phase. In this way, several urban planning alternatives could be analysed and evaluate before important transport infrastructure investment are made. The first part of the paper analyses the state of road accidents recorded in Bucharest. The second part of the paper demonstrates how the intersection conflict index can be used in traffic micro-simulation models to assess measures of traffic risk reducing.
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