Cross Intersection Research Articles

Highly Efficient Traffic Planning for Autonomous Vehicles to Cross Intersections Without a Stop

Waiting in a long queue at traffic lights not only wastes valuable time but also pollutes the environment. With the advances in autonomous vehicles and 5G networks, the previous jamming scenarios at intersections may be turned into non-stop weaving traffic flows. Toward this vision, we propose a highly efficient traffic planning system, namely DASHX, which enables connected autonomous vehicles to cross multi-way intersections without a stop. Specifically, DASHX has a comprehensive model to represent intersections and vehicle status. It can constantly process large volumes of vehicle information, resolve scheduling conflicts, and generate optimal travel plans for all vehicles coming toward the intersection in real time. Unlike existing works that are limited to certain types of intersections and lack considerations of practicability, DASHX is universal for any type of 3D intersection and yields the near-maximum throughput while still ensuring riding comfort. To better evaluate the effectiveness of traffic scheduling systems in real-world scenarios, we developed a sophisticated open source 3D traffic simulation platform (DASHX-SIM) that can handle complicated 3D road layouts and simulate vehicles’ networking and decision-making processes. We have conducted extensive experiments, and the experimental results demonstrate the practicality, effectiveness, and efficiency of the DASHX system and the simulator.

A before-after evaluation of protected right-turn signal phasings by applying Empirical Bayes and Full Bayes approaches with heterogenous count data models

Right-turn crashes (or left-turn crashes for the US or similar countries) represent over 40 % of signalized intersection crashes in Queensland, Australia. Protected right-turn phasings are a widely used countermeasure for right-turn crashes, but the research findings on their effects across different crash types and intersection types are not consistent. Methodologically, the Empirical Bayes and Full Bayes techniques are generally applied for before-after evaluations, but the inclusion of heterogeneous models within these techniques has not been considered much. Addressing these research gaps, the objective of this study is to evaluate the effectiveness of protected right-turn signal phasings at signalized intersections employing heterogeneous count data models with the Empirical Bayes and Full Bayes techniques. In particular, the Empirical Bayes approach based on random parameters Poisson-Gamma models (simulation-based Empirical Bayes), and the Full Bayes approach based on random parameters Poisson-Lognormal intervention models (simulation-based Full Bayes) are applied. A total of 69 Cross intersections (with ten treated sites) and 47 T intersections (with six treated sites) from Southeast Queensland in Australia were included in the analysis to estimate the effects of protected right-turn signal phasings on various crash types. Results show that the change of signal phasing from a permissive right-turn phasing to the protected right-turn phasing at cross and T intersections reduces about 87 % and 91 % of right-turn crashes, respectively. In addition, the effect of protected right-turn phasings on rear-end crashes was not significant. The heterogenous count data models significantly address extra Poisson variation, leading to efficient safety estimates in both simulation-based Empirical Bayes and simulation-based Full Bayes approaches. This study demonstrates the importance of accounting for unobserved heterogeneity for the before-after evaluation of engineering countermeasures.

Different path strategies for directed energy deposition of crossing intersections from stainless steel SS316L-Si

Additive manufacturing by directed energy deposition is of increasing interest within the scientific community. Over the past decade, this technology has gained ground with the production of parts from SS 316L-Si stainless steel, an industrial product in widespread use. Yet one of the main challenges when extending the use of this technology to the manufacture of medium complexity parts is how to achieve good intersections. This paper focuses on the use of Plasma Arc Welding (PAW) for the additive manufacturing of X-Cross intersections made of SS 316L-Si stainless steel alloy, defining its geometrical suitability and evaluating its productivity. Firstly, two strategies for the production of parts are presented: the energy control strategy on the curved path of a L-shaped wall and the variable amplitude waveform strategy (variable waving) for the continuous production of a X-cross intersection. A metallographic analysis of the samples extracted in the different tests was completed, focusing mainly on the transversal direction. Next, four deposition strategies based on discrete trajectories (cross-overlapping and cross-waving) and on continuous trajectories (waving and overlapping) are addressed in this paper for the production of cross intersections in a part of medium complexity and for the extension of its use in Near-Net-Shape (NNS) manufacturing. The mechanical properties and microstructure of samples manufactured with these deposition strategies are analysed by means of tensile tests and metallographic characterization. An analysis of the deposition energy and of the productivity is carried out for the four strategies. The productivity is analysed by means of different parameters such as the number of layers, the actual deposition rate and process times (deposition time, waiting time, standby time and idle time). The most advantageous strategies in terms of productivity were cross-waving and waving, achieving torch utilization rates relative to total time of 50 %. Methodologies and conditions for the manufacture of X-cross intersections are established. Finally, a study of the cross-intersection geometry obtained for each deposition strategy is performed. From the geometrical analysis of the crosses produced, it has been observed that the ratio of material used in the cross-overlapping sequence to produce a X-cross intersection in relation to the amount of material deposited is more than 10 % higher than in the other strategies.

The Control of PMSM Motor to Drive Propeller in Ship Propulsion System

Electric propulsion has advantages such as high maneuverability, good safety and reliability, being able to operate optimally with a control system. It is a future green technology which is environmentally friendly. The application of electric propulsion for ship is that the propeller is driven by using electric motor by regulating speed and/or torque. in this research, an permanent magnet synchronous motor (PMSM) is used to drive propeller of ship propulsion. The controller of proportional integral (PI) scheme is proposed to drive electric motor. The method of Ziegler Nichols stability margin tuning rule algorithm is performed to search the controller parameters. The optimal working point of propeller is determined by the cross intersection between the propeller loading curve to the coefficient of thrust curve of open water test propeller. The speed from the result of propeller working point analysis is set as control input reference. Based on the results of simulation, the proposed control of electric propulsion using PMSM motor is able to achieve the reference of speed.

Motion planning in complex urban environments: An industrial application on autonomous last‐mile delivery vehicles

AbstractIn this article, a motion planning framework for autonomous driving is explored to achieve unmanned last‐mile delivery vehicle application in complicated urban scenario. This approach can dramatically improve the intelligence, driving safety, driving robustness, and scalability of autonomous vehicles. In this framework, a specific High‐Definition (HD) map representation was proposed for last‐mile delivery applications, and a Route Planning layer generates a kinematically feasible reference line with smoothness condition based on Routing and HD Map components. Then a Scenario Planning layer considers routing results and both static and dynamic obstacles into account to select a corresponding scenario to execute, such as cruise on‐road scenario, cross intersection scenario, parking scenario, and so forth. Finally, a Trajectory Planning layer which is classified with trajectory generation and optimization modules is described. In the trajectory generation part, a rough path–speed profile and corresponding decisions, such as nudge, stop, yield, and so forth, are generated. Then, the rough path–speed profile is postprocessed by optimization algorithms in the trajectory optimization part. On the basis of the real road test results from thousands of times for JD.com's real autonomous delivery vehicle operations and approximate 115,475 km of fully autonomous driving mode in an urban scenario, the proposed motion planning framework demonstrates the efficiency of autonomous driving, improves the driving quality and reduces the manual intervention.

The Effect of Physical Environment Risk Factors on Vehicle Collisions Severity Involving Child-Pedestrians in Malaysia

This study is aimed at investigating the association between child-pedestrian severity levels of collisions and physical environmental variables. The outcome of this study could be applied to road safety intervention for improving engineering modifications related to children pedestrians. The retrospective analysis was carried out using 6-year data from Royal Malaysia Police records from the years 2009 to 2014. Multinomial logit modeling (MNL) was applied. The results demonstrated that the injury severity of the collisions is related to road geometry, road surface material, road surface condition, traffic system, road marking, traffic control type, lighting condition, speed limit, time of collision, type of location, and land use characteristics. Specifically, fatal injury collisions are significantly increased by t/y intersection; concrete and earth-road surfaces; two-way traffic and dual carriageways; posted speed limits of 70 to 90 km/h; time of collision: 0 to 0659 hours (early morning) and 0700 to 0959 hours (morning); lighting conditions, including dark without street light, and dark with street light; and control type involving police. Meanwhile, cross intersections’ posted speed limits of 80 km/h to 90 km/h and the time of collision from 0 to 0659 hours (early morning) and 1900 to 2459 hours (night), significantly increased serious injury collisions. Notably, the findings revealed the importance of more in-depth studies on physical environmental features that relate to child-pedestrians’ severity level of collisions. This is essential for improvements to physical environmental designs by policymakers. Thus, policymakers and stakeholders can utilize the findings to further improve the physical environment through structure and design.

Mode Switching Control Using Lane Keeping Assist and Waypoints Tracking for Autonomous Driving in a City Environment

This paper proposes a mode switching supervisory controller for autonomous vehicles. The supervisory controller selects the most appropriate controller based on safety constraints and on the vehicle location with respect to junctions. Autonomous steering, throttle and deceleration control inputs are used to perform variable speed lane keeping assist, standard or emergency braking and to manage junctions, including roundabouts. Adaptive model predictive control with lane keeping assist is performed on the main roads and a linear pure pursuit inspired controller is applied using waypoints at road junctions where lane keeping assist sensors present a safety risk. A multi-stage rule based autonomous braking algorithm performs stop, restart and emergency braking maneuvers. The controllers are implemented in MATLAB® and Simulink™ and are demonstrated using the Automatic Driving Toolbox™ environment. Numerical simulations of autonomous driving scenarios demonstrate the efficiency of the lane keeping assist mode on roads with curvature and the ability to accurately track waypoints at cross intersections and roundabouts using a simpler pure pursuit inspired mode. The ego vehicle also autonomously stops in time at signaled intersections or to avoid collision with other road users.

Using latent class clustering and binary logistic regression to model Australian cyclist injury severity in motor vehicle–bicycle crashes

Introduction: In recent years, Australia is seeing an increase in the total number of cyclists. However, the rise of serious injuries and fatalities to cyclists has been a major concern. Understanding the factors affecting the fatalities and injuries of bicyclists in crashes with motor vehicles is important to develop effective policy measures aimed at improving the safety of bicyclists. This study aims to identify the factors affecting motor vehicle-bicycle (MVB) crashes in Victoria, Australia and introducing effective countermeasures for the identified risk factors. Method: A data set of 14,759 MVB crash records from Victoria, Australia between 2006 and 2019 was analyzed using the binary logit model and latent class clustering. Results: It was observed that the factors that increase the risk of fatalities and serious injuries of bicyclists (FSI) in all clusters are: elderly bicyclist, not using a helmet, and darkness condition. Likewise, in areas with no traffic control, clear weather, and dry surface condition (cluster 1), high speed limits increase the risk of FSI, but the occurrence of MVB crashes in cross intersection and T-intersection has been significantly associated with a reduction in the risk of FSI. In areas with traffic control and unfavorable weather conditions (cluster 2), wet road surface increases the risk of FSI, but the areas with give way sign and pedestrian crossing signs reduce the risk of FSI. Practical Applications: Recommendations to reduce the risk of fatalities or serious injury to bicyclists are: improvement of road lighting and more exposure of bicyclists using reflective clothing and reflectors, separation of the bicycle and vehicle path in mid blocks especially in high-speed areas, using a more stable bicycle for the older people, monitoring helmet use, improving autonomous emergency braking, and using bicyclist detection technology for vehicles.

Tandem Design of Bus Priority Based on a Pre-Signal System

Giving buses priority is an important measure to improve the attractiveness of public transport and to reduce urban traffic congestion. Reducing bus service delays as much as possible will have a positive impact on urban traffic. Based on the pre-signal system, a bus at an intersection with a left-turn special phase is optimized by “tandem design”. The design model is applied to the entrance of an intersection to study the process of vehicle arrival and departure at the main signal and pre-signal, and to calculate and analyze the delay changes of buses, straight social vehicles (meaning vehicles other than those required to be open to traffic) and left-turn vehicles before and after the adoption of “tandem design”. The results show that when the vehicle capacity at the intersection is saturated, the delays to buses and the delays of left-turn vehicles will be significantly reduced once the “tandem design” is adopted at the entrance of a cross intersection with a special left-turn phase. However, it has little effect on the delay of straight-on vehicles; with this system, the total delay experienced by straight vehicles will be reduced to one cycle.

Signal timing optimization design of cross intersection-- A Case study of The intersection of Minzhu South Road and Fengshou Road in Jiaozuo City

The capacity of intersection affects the maximum capacity of road to a certain extent. The traffic capacity of the intersection can be improved to some extent by optimizing and adjusting the parameters of the signal timing model. Taking the cross-type intersection at the intersection of Minzhu South Road and Fengshou Road in Jiaozuo City as the research background, this study optimizes the signal timing design for the current intersection, optimizes the signal timing design by using Webster algorithm, and conducts simulation by using traffic simulation software VISSIM. The results showed that the average delay at the intersection was reduced by nearly seven seconds.

Positioning Practices of Orientation and Mobility Specialists When Teaching Street Crossings: Is There a Standard Approach?

Introduction: An important skill for orientation and mobility (O&M) specialists to have is to monitor clients appropriately when they are learning to cross intersections. Techniques books provide some suggestions for positioning during street crossings, but no research has been conducted about consensus or priorities for making appropriate decisions on positioning. The purpose of this study was to investigate general positioning decisions using visual monitoring techniques. Method: A total of 234 participants (practicing O&M specialists, preservice O&M students, and O&M university personnel) completed a 40-question survey. The survey included demographic questions, diagrams of intersections that participants used to select positioning locations, questions about lanes of threat, and questions about important factors to consider when positioning to monitor safety. Commonality of selections were analyzed and compared with demographic information. Results: The greatest consensus was found for all intersection types when the client is positioned on the corner waiting to cross and for identification of the first lane of threat. More variable position selections were made for monitoring during the crossings, and the second and third lane of threat selections were also more variable. Factors respondents indicated as most important to consider when positioning aligned with their positioning choices overall. Discussion: Personnel preparation programs may want to consider to what extent they teach considerations for positioning before and during crossings, and whether the predominant tendency to put oneself between the client and traffic warrants additional conversation. Future research should look at more complex intersections and the additional nuances used to make positioning choices. Implications for practitioners: Practitioners should reflect on whether they actively change their positioning decisions based on the situation and type of intersection versus tending to use a standard strategy.

Modeling traffic noise level near at-grade junctions: Roundabouts, T and cross intersections

This study set out to model the traffic noise level at intersections as a function of a set of variables from traffic characteristics, geometric features, pavement surface condition, and traffic management. A drone was used to take the video from traffic flow at the same time as measuring traffic noise level via a sound level meter. Regression modeling was used to determine the influential variables and their contribution to generated noise level at signalized T-intersections, cross-intersections, and roundabouts. The results showed that number of vehicles, and pavement condition index and speed together with the total traffic volume have significant impacts on the noise level. Furthermore, the traffic noise level at the exit approaches is higher than that at the entrance approaches of roundabouts. Moreover, the unexpected events and non-lane-based behavior caused a sudden increase in the maximum sound level at exit approaches.

China-Pakistan Economic Corridor at the Cross Intersection of China, Central Asia and South Asia: Opportunities for Regional Economic Growth

Pakistan’s geographical location is ideal for China-Pakistan Economic Corridor (CPEC) Project, and it formally recognizes as an iconic model of Belt and Road Initiative (BRI) plan. This corridor is laid at the cross intersection of three regions of economic growth include: China, Central Asian Republics and South Asia. It plays a vital role of inter-connectivity between these three regions, where three billions of inhabitants live, which is roughly half of the world population. The central argument of the paper is sternly conceptual and based on the subsequent arguments: foremost, the foundation of CPEC project is a green signal for the regional connectivity, mutual cooperation, economic growth and stability of the entire region of South and Central Asia. Secondly, the topographical position of Pakistan has an incredible potential for corridor development and manipulation process. Thirdly, due to the iconic model of belt and road initiative plan, the CPEC corridor has broad potential for regional economic growth because of shared boundaries and cross intersection position with China, CARs and South Asia. Finally, with the copious fruitful opportunities, this project facades somber challenges internally and outwardly. Hence, this study uses a positive-sum logic to analyze central argument and also discusses the policy inputs that may be prolific for regional growth and reforms of the project.

PREDICTIVE MODELLING OF TRAFFIC FLOWFLOW IN AKURE, NIGERIA: UNSIGNALIZED INTERSECTIONS IN FOCUS

Unsignalized intersections namely two-way stop-controlled intersection (TWSC) and all-way stop-controlled intersection (AWSC) are widely used in Akure. Five intersections consisting of three Tee and two Cross that were critical to traffic flow in the study area were selected for study. Data on geometric features were collected using odometer, while traffic parameters were captured and metered using cine camera placed at a vantage point from the road section during peak and off-peak periods on week days. Traffic flows at the intersections were expressed as functions of traffic characteristics and geometric features of the approaches; while the effect of distances of intersections before and after the intersections studied were also incorporated as a correction factors in the models. The models were developed using multiple linear regression technique with the aid of SPSS software and validated with empirical data other than those used for model calibration. Adjusted R2 values of 0.881 and 0.882 were obtained for Tee and Cross intersections respectively for peak period, while 0.938 and 0.940 respectively were obtained for the off-peak period. These indicate that the flow models are very robust in replicating the observed data. The predictive models have the potential to accurately estimate traffic flow at intersections in the study area and other cities of the world with similar traffic conditions.

PREDICTIVE MODELLING OF TRAFFIC FLOWFLOW IN AKURE, NIGERIA: UNSIGNALIZED INTERSECTIONS IN FOCUS

Unsignalized intersections namely two-way stop-controlled intersection (TWSC) and all-way stop-controlled intersection (AWSC) are widely used in Akure. Five intersections consisting of three Tee and two Cross that were critical to traffic flow in the study area were selected for study. Data on geometric features were collected using odometer, while traffic parameters were captured and metered using cine camera placed at a vantage point from the road section during peak and off-peak periods on week days. Traffic flows at the intersections were expressed as functions of traffic characteristics and geometric features of the approaches; while the effect of distances of intersections before and after the intersections studied were also incorporated as a correction factors in the models. The models were developed using multiple linear regression technique with the aid of SPSS software and validated with empirical data other than those used for model calibration. Adjusted R2 values of 0.881 and 0.882 were obtained for Tee and Cross intersections respectively for peak period, while 0.938 and 0.940 respectively were obtained for the off-peak period. These indicate that the flow models are very robust in replicating the observed data. The predictive models have the potential to accurately estimate traffic flow at intersections in the study area and other cities of the world with similar traffic conditions.

Numerical simulation and scaling of droplet deformation in a hyperbolic flow.

Motivated by a recent experiment (C. Ulloa et al., Phys. Rev. E 89, 033004 (2014)), droplet deformation in a flat microfluidic channel having a cross intersection with two inlet channels and two outlet channels, i.e. hyperbolic flow, is numerically investigated. Employing the boundary element method (BEM), we numerically solve the Darcy equation in the two dimensions and investigate droplet motion and droplet deformation as the droplet enters the cross intersection. We numerically find that the maximum deformation of droplet depends on droplet size, capillary number, viscosity ratio and flow rate ratio of the two inlets. Our numerical scaling is in good agreement with the experimental scaling report.

An efficient adaptive intelligent routing system for multi-intersections

With the rapid development of wireless technologies and the growing emphasis on vehicle safety, many vehicular ad hoc network applications have been extensively used. This study attempts to use vehicular ad hoc network technologies for autonomous driving to improve and reduce traffic congestion and vehicle waiting time. Therefore, this study proposes an adaptively intelligent routing system, which uses V2V communications to increase vehicle speed, allows vehicles to communicate with traffic control systems, arranges appropriate vehicle routes based on queuing theory, and uses traffic signals for information exchange. The timing of traffic signals is decided according to road traffic density. To decrease vehicle waiting time at intersections, every vehicle's speed is adjusted based on the distance between the vehicle and the traffic signals. In the simulation, automated vehicles and a more realistic car-following model are taken into consideration and vehicle speeds are regulated based on speed limits and safe following distance on most roads. The simulation result reveals that our proposed adaptively intelligent routing system outperforms periodic system in average vehicle speed and average waiting time at both single and double cross intersections. Copyright © 2016 John Wiley & Sons, Ltd.

Traffic design and signal timing of staggered intersections based on a sorting strategy

A staggered intersection is a special type of intersection in a road network. Its geographical characteristics consist of two T-legged intersections that cause the lost time per cycle to become longer than at cross intersections under conventional signal control, thus leading to low intersection efficiency. This article shows that the problem can be eliminated at the left–right type of staggered intersection by channelization and signal phasing, based on a sorting strategy and pre-signal, which reduce the amount of lost time during the signal cycle using the split distance as the sorting area. VISSIM was used to model and analyze the proposed method as well as the conventional method for comparison purposes. The simulation revealed that the proposed method reduced the average delays and maximum queue lengths in each movement and for the entire intersection, both in the peak hours and in the off-peak hour.

MORPHOLOGICAL FEATURES OF REGENERATION OF THE ACHILLES TENDON AFTER ITS CROSS TENOTOMY WITH INTERSECTION OF FASCIAL SHEATHS AND DAMAGE OF MESENTERIC VESSELS

The article is aimed to study morphological features of regeneration process of the Achilles tendon after its cross tenotomy with intersection of facial sheaths and damage of mesenteric vessels in experiment on growing rabbits. The experiment was made on 25 rabbits of «Shinshilla» breed of both sexes in the age of one month with the mass of 1376±124,8 g. The processes of reparative regeneration of heel tendon were investigated. There was used a rabbit’s output from the experiment on 15, 21,30,60 and 90 days after cross tenotomy in number of five animal units. According to results of carried out researches, the considerable part of defect was completed by dense connective tissue obtaining scarry character on 60 days. There was observed an opposite development of defect zone, a focal substitution of dense fibrous tissue by loose connective tissue with histiocytic, lymphoid cells and inclusions of foci of fatty tissue on 90 days. The authors didn’t noted the complete recovery of tendinous tissues «retitucica ad integrum» in the zone of tenotomy, because of circulatory disturbance in this area due to damage of facial sheats and mesenteric vessels. Thereby, the reparative regeneration of heel tendon was originated in unfavorable conditions, because of cross tenotomy performance with intersection of synovial sheath and damage of mesenteric vessels. The results obtained indicated that it is necessary to avoid the damage of synovial sheathes and mesenteric vessels in cross intersection of heel tendon during correction of foot element deformations.

Estimation of the noise level produced by road traffic in roundabouts

Many studies of the environmental impact in urban areas are related to road traffic noise. The noise generated by road traffic is more disturbing near junctions, where multiple flows are intersecting. It is largely accepted that converting a cross intersection into a roundabout the noise level will decrease. This article presents a study made on a hypothetic intersection, for two different configurations: signalized cross intersection and roundabout. The traffic flow data were detailed near and inside the intersection, using traffic flow speeds measured in real conditions, for passenger cars. The analysis was made using the noise mapping software LimA. The results show that there are differences in the resulted noise levels when the intersection is detailed and these differences may affect the measures that can be undertaken by the local authorities for noise abatement. In most cases even the changes in the road network should be preceded by such analysis.