Influences of Mixed Traffic Flow and Time Pressure on Mistake-Prone Driving Behaviors among Bus Drivers

Bus safety is a matter of great importance in many developing countries, with driving behaviors among bus drivers identified as a primary factor contributing to accidents. This concern is particularly amplified in mixed traffic flow (MTF) environments with time pressure (TP). However, there is a lack of sufficient research exploring the relationships among these factors. This study consists of two papers that aim to investigate the impact of MTF environments with TP on the driving behaviors of bus drivers. While the first paper focuses on violated driving behaviors, this particular paper delves into mistake-prone driving behaviors (MDB). To collect data on MDB, as well as perceptions of MTF and TP, a questionnaire survey was implemented among bus drivers. Factor analyses were employed to create new measurements for validating MDB in MTF environments. The study utilized partial correlation and linear regression analyses with the Bayesian Model Averaging (BMA) method to explore the relationships between MDB and MTF/TP. The results revealed a modified scale for MDB. Two MTF factors and two TP factors were found to be significantly associated with MDB. A high presence of motorcycles and dangerous interactions among vehicles were not found to be associated with MDB among bus drivers. However, bus drivers who perceived motorcyclists as aggressive, considered road users’ traffic habits as unsafe, and perceived bus routes’ punctuality and organization as very strict were more likely to exhibit MDB. Moreover, the results from the three MDB predictive models demonstrated a positive impact of bus route organization on MDB among bus drivers. The study also examined various relationships between the socio-demographic characteristics of bus drivers and MDB. These findings are of practical significance in developing interventions aimed at reducing MDB among bus drivers operating in MTF environments with TP.

Potential Application of iRap for Road Safety Assessment under Mixed Traffic Condition Case Study: Le Van Viet Street in Ho Chi Minh City

Road transport safety policies have emphasized road infrastructure safety design and engineering as a core function.However,in developing countries like Vietnam,this approach has been slower to adopt,resulting in substandard roads.In-depth studies of accident locations indicate that road environment factors contribute significantly to road accidents in Vietnam and road design features are associated with specific accident types and hazards.Proactive and reactive approaches,such as road safety audit,inspection,assessment,and treatment of hazardous locations,are necessary to ensure that the road and its environment are safe.This paper provides an overview of road safety in Vietnam in general,and Ho Chi Minh in particular,including its factors and characteristics,as well as road infrastructure safety improvements.The iRap tool for road safety inspection and assessment is highlighted as a potential method for systematically analyzing road infrastructure deficiencies and providing targeted countermeasures to improve road safety under mixed traffic conditions.

Mixed traffic flow modeling near Chinese bus stops and its applications

To determine how bus stop design influences mixed traffic operation near Chinese bus stops,a new theoretical method was developed by using additive-conflict-flows procedure.The procedure was extended from homogeneous traffic flow to mixed traffic flow.Based on the procedure and queuing theory,car capacity and speed models were proposed for three types of bus stops including curbside,bus bay and bicycle detour.The effects of various combinations of bus stop type,traffic volume,bus dwell time,and berth number on traffic operations were investigated.The results indicate that traffic volume,bus dwell time and berth number have negative effects on traffic operations for any type of bus stops.For different types of bus stops,at car volumes above approximately 200 vehicles per hour,the bus bay and bicycle detour designs provide more benefits than the curbside design.As traffic volume increases,the benefit firstly increases in uncongested conditions and then decreases in congested conditions.It reaches the maximum at car volumes nearly 1 100 vehicles per hour.The results can be used to aid in the selection of a preferred bus stop design for a given traffic volume in developing countries.

Interaction-Aware Cut-In Trajectory Prediction and Risk Assessment in Mixed Traffic

Accurately predicting the trajectories of surrounding vehicles and assessing the collision risks are essential to avoid side and rear-end collisions caused by cut-in.To improve the safety of autonomous vehicles in the mixed traffic,this study proposes a cut-in prediction and risk assessment method with considering the interactions of multiple traffic participants.The integration of the support vector machine and Gaussian mixture model(SVM-GMM)is developed to simultaneously predict cut-in behavior and trajectory.The dimension of the input features is reduced through Chebyshev fitting to improve the training efficiency as well as the online inference performance.Based on the predicted trajectory of the cut-in vehicle and the responsive actions of the autonomous vehicles,two risk measurements are introduced to formulate the comprehensive interaction risk through the combination of Sigmoid function and Softmax function.Finally,the comparative analysis is performed to validate the proposed method using the naturalistic driving data.The results show that the proposed method can predict the trajectory with higher precision and effectively evaluate the risk level of a cut-in maneuver compared to the methods without considering interaction.

Dynamics of Motorized Vehicle Flow under Mixed Traffic Circumstance

To study the dynamics of mixed traffic flow consisting of motorized and non-motorized vehicles, a carfollowing model based on the principle of collision free and cautious driving is proposed. Lateral friction and overlapping driving are introduced to describe the interactions between motorized vehicles and non-motorized vehicles. By numerical simulations, the flux-density relation, the temporal-spatial dynamics, and the velocity evolution are investigated in detail The results indicate non-motorized vehicles have a significant impact on the motorized vehicle flow and cause the maximum flux to decline by about 13%. Non-motorized vehicles can decrease the motorized vehicle velocity and cause velocity oscillation when the motorized vehicle density is low. Moreover, non-motorized vehicles show a significant damping effect on the oscillating velocity when the density is medium and high, and such an effect weakens as motorized vehicle density increases. The results also stress the necessity for separating motorized vehicles from non-motorized vehicles.

Markov chain-based platoon recognition model in mixed traffic with human-driven and connected and autonomous vehicles

Many vehicle platoons are interrupted while traveling on roads,especially at urban signalized intersections.One reason for such interruptions is the inability to exchange real-time information between traditional human-driven vehicles and intersection infrastructure.Thus,this paper develops a Markov chain-based model to recognize platoons.A simulation experiment is performed in Vissim based on field data extracted from video recordings to prove the model’s applicability.The videos,recorded with a high-definition camera,contain field driving data from three Tesla vehicles,which can achieve Level 2 autonomous driving.The simulation results show that the recognition rate exceeds 80%when the connected and autonomous vehicle penetration rate is higher than 0.7.Whether a vehicle is upstream or downstream of an intersection also affects the performance of platoon recognition.The platoon recognition model developed in this paper can be used as a signal control input at intersections to reduce the unnecessary interruption of vehicle platoons and improve traffic efficiency.

Mathematical Modeling,Field Calibration and Numerical Simulation of Low-Speed Mixed Traffic Flow in Cities

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Characteristics of synchronized traffic in mixed traffic flow

In this paper, the characteristics of synchronized traffic in mixed traffic flow are investigated based on the braking light model. By introducing the energy dissipation and the distribution of slowdown vehicles, the effects of the maximum velocity, the mixing ratio, and the length of vehicles on the synchronized flow are discussed. It is found that the maximum velocity plays a great role in the synchronized flow in mixed traffic. The energy dissipation and the distribution of slowdown vehicles in the synchronized flow region are greatly different from those in free flow and a traffic jamming region. When all of vehicles have the same maximum velocity with Vmax 〉 15, the mixed traffic significantly displays synchronized flow, which has been demonstrated by the relation between flow rate and occupancy and estimation of the cross-correlation function. Moreover, the energy dissipation in the synchronized flow region does not increase with occupancy. The distribution of slowdown vehicles shows a changeless platform in the synchronized flow region. This is an interesting phenomenon. It helps to deeply understand the synchronized flow and greatly reduce the energy dissipation of traffic flow.

Mixed Traffic Flow Capacity of More Major Lanes Unsignalized Intersection

Highway capacity is defined as maximum volume of traffic flow through the particular highway section under given traffic conditions, road conditions and so on. Highway construction and management is judged by capacity standard. The reasonable scale and time of highway construction, rational network structure and optimal management mode of highway network can be determined by analyzing the fitness between capacity and traffic volume. All over the world, highway capacity is studied to different extent in different country. Based on the gap acceptance theory, the mixed traffic flow composed of two representative vehicle types heavy and light vehicles is analyzed with probability theory. Capacity model of the minor mixed traffic flows crossing m major lanes, on which the traffic flows fix in with M3 distributed headway, on the unsignalized intersection is set up, and it is an extension of minor lane capacity theory for one vehicle-type and one major-lane traffic flow.

Analysis of occupation time of vehicles at urban unsignalized intersections in non-lane-based mixed traffic conditions

In India, traffic flow on roads is highly mixed in nature with wide variations in the static and dynamic characteristics of vehicles. At unsignalized intersections, vehicles generally do not follow lane discipline and ignore the rules of priority. Drivers generally become more aggressive and tend to cross the uncontrolled intersections without considering the conflicting traffic. All these conditions cause a very complex traffic situation at unsignal- ized intersections which have a great impact on the capacity and performance of traffic intersections. A new method called additive conflict flow （ACF） method is suitable to determine the capacity of unsignalized inter- sections in non-lane-based mixed traffic conditions as prevailing in India. Occupation time is the key parameter for ACF method, which is defined as the time spent by a vehicle in the conflict area at the intersection. Data for this study were collected at two three-legged unsignalized intersections （one is uncontrolled and other one is semi- controlled） in Mangalore city, India using video-graphic technique during peak periods on three consecutive week days. The occupation time of vehicles at these intersections were studied and compared. The data on conflicting traffic volume and occupation time by each subject vehicle at the conflict area were extracted from the videos using image processing software. The subject vehicles were divided into three categories： two wheelers,cars, and auto-rickshaws. Mathematical relationships were developed to relate the occupation time of different cate- gories of vehicles with the conflicting flow of vehicles for various movements at both the intersections. It was found that occupation time increases with the increasing con- flicting traffic and observed to be higher at the uncontrolled intersection compared to the semicontrolled intersec- tion. The segregated turning movements and the presence of mini roundabout at the semicontrolled intersection reduces the conflicts of vehicular movements, which ulti- mately reduces the occupation time. The proposed methodology will be useful to determine the occupation time for various movements at unsignalized intersections. The models developed in the study can be used by practitioners and traffic engineers to estimate the capacity of unsignalized intersections in non-lane-based discipline and mixed traffic conditions.

Simulation of High-Level Way Toll System under the Condition of Mixed Traffic Flow

Parking-toll on main-line is one of toll models on high-level ways in our country at present. This paper analyzes the flow's distributing function, queuing model, and vehicle passing time. Through computer simulation, the negative index relationships between carrying capacity and serving time, and the index relationships between the queuing delay and flow are gained under the condition of different serving time and different vehicle type composition. When the flow density is low, the vehicle type composing has less influence on system serving level. Contrarily, also. Disposing toll station by roadway where flow density is high, we can save transection areas of toll station, reduce system queuing delay time, and enhance carrying capacity of toll station.

Gap acceptance behavior of drivers at uncontrolled T-intersections under mixed traffic conditions

Explicit traffic control measures are absent in uncontrolled intersections which make them susceptible to frequent conflicts and resulting collisions between vehicles. In developing countries like India, drivers at such intersections do not yield to higher priority movements which cause more crashes between vehicles. The objective of this study is to analyze and model the gap acceptance behavior of minor street drivers at uncontrolled T-intersections considering their aggressive nature. Three intersections in the northeast region of India have been selected as the case study area. Preliminary analysis of the data revealed that drivers behave aggressively, not because they have to wait for a long time at the stop line, but because of their lack of respect for traffic rules. Binary logit models are developed for minor road right turning vehicles which show that gap acceptance behavior is influenced by gap duration, clearing time and aggressive nature of drivers. The equations obtained were used to estimate the critical gaps for aggressive and non-aggressive drivers. Critical gaps are also calculated using an existing method called clearing behavior approach. It is also shown that the estimation of critical gap is more realistic if clearing time and aggressive behavior of drivers are considered.

Bi-level ramp merging coordination for dense mixed traffic conditions

Connected and Autonomous Vehicles(CAVs)hold great potential to improve traffic efficiency,emissions and safety in freeway on-ramp bottlenecks through coordination between mainstream and on-ramp vehicles.This study proposes a bi-level coordination strategy for freeway on-ramp merging of mixed traffic consisting of CAVs and human-driven vehicles(HDVs)to optimize the overall traffic efficiency and safety in congested traffic scenarios at the traffic flow level instead of platoon levels.The macro level employs an optimization model based on fundamental diagrams and shock wave theories to make optimal coordination decisions,including optimal minimum merging platoon size to trigger merging coordination and optimal coordination speed,based on macroscopic traffic state in mainline and ramp(i.e.,traffic volume and penetration rates of CAVs).Furthermore,the micro level determines the real platoon size in each merging cycle as per random arrival patterns and designs the coordinated trajectories of the mainline facilitating vehicle and ramp platoon.A receding horizon scheme is implemented to accommodate human drivers’stochastics as well.The developed bi-level strategy is tested in terms of improving efficiency and safety in a simulation-based case study under various traffic volumes and CAV penetration rates.The results show the proposed coordination addresses the uncertainties in mixed traffic as expected and substantially improves ramp merging operation in terms of merging efficiency and traffic robustness,and reducing collision risk and emissions,especially under high traffic volume conditions.

Impacts of bus holding strategy on the performance and pollutant emissions of a two-lane mixed traffic system

This paper investigates the impacts of a bus holding strategy on the mutual interference between buses and passenger cars in a non-dedicated bus route,as well as the impacts on the characteristics of pollutant emissions of passenger cars.The dynamic behaviors of these two types of vehicles are described using cellular automata(CA)models under open boundary conditions.Numerical simulations are carried out to obtain the phase diagrams of the bus system and the trajectories of buses and passenger cars before and after the implementation of the bus holding strategy under different probabilities of passenger cars entering a two-lane mixed traffic system.Then,we analyze the flow rate,satisfaction rate,and pollutant emission rates of passenger cars together with the performance of a mixed traffic system.The results show that the bus holding strategy can effectively alleviate bus bunching,whereas it has no significant impact on the flow rate and pollutant emission rates of passenger cars;the flow rate,satisfaction rate,and pollutant emission rates of passenger cars for either the traffic system or for each lane are influenced by the bus departure interval and the number of passengers arriving at bus stops.

Effects of Driver Response Time Under Take‑Over Control Based on CAR‑ToC Model in Human–Machine Mixed Traffic Flow

The take-over control(ToC)of human–machine interaction is a hotspot.From automatic driving to manual driving,some factors affecting driver response time have not been considered in existing models,and little attention has been paid to its effects on mixed traffic flow.This study establishes a ToC model of response based on adaptive control of thought-rational cognitive architecture(CAR-ToC)to investigate the effects of driver response time on traffic flow.A quantification method of driver’s situation cognition uncertainty is also proposed.This method can directly describe the cognitive effect of drivers with different cognitive characteristics on vehicle cluster situations.The results show that when driver response time in ToC is 4.2 s,the traffic state is the best.The greater the response time is,the more obvious the stop-and-go waves exhibit.Besides,crashes happen when manual vehicles hit other types of vehicles in ToC.Effects of driver response time on traffic are illustrated and verified from various aspects.Experiments are designed to verify that road efficiency and safety are increased by using a dynamic take-over strategy.Further,internal causes of effects are revealed and suggestions are discussed for the safety and efficiency of autonomous vehicles.

Evaluation of platooning configurations for connected and automated vehicles at an isolated roundabout in a mixed traffic environment

Platooning has emerged to be one of the most promising applications for connected and automated vehicles(CAVs).However,there is still limited research on the effect of platooning configurations.This study sets out to investigate the effect of CAV platoon configurations at a typical isolated roundabout in a mixed traffic environment.Investigated platoon configurations include maximum platoon size,platoon willingness,and platoon type.Extensive simulation experiments are carried out in simulation of urban mobility(SUMO),considering various traffic conditions,including different penetration rates,traffic flows,and turning percentages.Results show that:(1)increasing the maximum platoon size and platoon willingness generally improves the throughput increment and delay reduction;and(2)heterogeneous platoons outperform homogeneous platoons in all traffic conditions.

Overtaking behaviour of vehicles on undivided roads in non-lane based mixed traffic conditions

Traffic on Indian roads is highly mixed in nature with wide variations in the static and dynamic characteristics of vehicles. These vehicles do not follow strict lane discipline and occupy any available lateral position on the road space. Overtaking is one of the most complex and important manoeuvre on undivided roads where the vehicles use the opposing lane to overtake the slower vehicles with the presence of oncoming vehicles from opposite direction. They are unavoidable especially in the case of mixed traffic conditions where there is always a speed difference between the fast and slow moving vehicles. Overtaking process involves lane-changing manoeuvres, acceleration and deceleration actions and estimation of relative speed of overtaking and overtaken vehicles, and also, estimation of speed and distance of the oncoming vehicle. The main objective of the present study is to study the overtaking characteristics of vehicles on undivided roads under mixed traffic conditions. For this purpose, details of overtaking data were collected on a two-lane two-way undivided road using moving car observer method and registration plate method. The overtaking characteristics of all types of vehicles under mixed traffic conditions were observed and mathematically modelled. The data extracted and analysed were the acceleration characteristics, speeds of the overtaking vehicles, overtaking time, overtaking distances, safe opposing gap required for overtaking, flow rates, overtaking frequencies, types of overtaking strategy, and types of overtaking and overtaken vehicles. Two types of overtaking strategies were observed in the field such as flying overtaking and accelerative overtaking. Graphs were plotted between the relative speed of the overtaking and overtaken vehicles against the overtaking time and negative correlation was found between the speed differential and total overtaking time for all categories of vehicles. It was observed that the number of overtaking increases with increase in the flow rate in the on-going direction and decreases with increase in flow in the opposite direction, The results obtained from this study will be useful to understand the overtaking behaviour of vehicles in mixed and non-lane discipline traffic conditions. These parameters will be useful in the development of traffic simulations models for undivided roads and thereby for estimation of capacity. The findings from the study can also be used to estimate potential collision times which will be helpful to improve the road safety.

Operational characteristics of mixed traffic flow under bi-directional environment using cellular automaton

Mixed traffic flow composed of autos and non-autos widely exists in developing countries and areas. To investigate the operational characteristics of the mixed traffic flow consisting of vehicles in different types （large vehicles, cars, and bicycles）, we develop a cellular automaton model to repli- cate the travel behaviors on a bi-directional road segment with respect to the physical and mechanic features of different vehicle types. By implementing the essential parameters calibrated through the field data collection, a numerical study is carried out considering the variation in volume, density, and velocity with different compositions of mixed traffic flows. The primary findings include： the average ve- locity of traffic flow and total volume decrease 60% and 30% after incorporating 10% bicycles, respectively; the phenomenon of double-summit in terms bicycle is beyond 60 % ; the maximal total volume higher than 10 %. of the total volume appears when the proportion of starts to recover when the proportion of bicycle is

Car capacity near bus stops with mixed traffic derived by additive-conflict-flows procedure

To determinate car capacity at bus stops with mixed traffic, a new theoretical approach was developed on the basis of additive-conflict-flows procedure. The procedure was extended from homogeneous traffic flow to mixed traffic flow. The conflicts among cars, buses and bicycles near the stop can be described by the extended procedure. The procedure can be understood more easily than the theory of gap acceptance. Car capacity near the stop is the function of both bus stream and bicycle stream. The proposed model can also analyze the cases of pedestrian effects and limited priority of bicyclists. Numerical results show that the car capacity decreases with the increasing flow rates of other streams. In addition, pedestrian effects and bicyclist's limited priority have negative effects on car capacity near bus stops with mixed traffic flow.

Modeling Mixed Traffic Flow at Crosswalks in Micro-Simulations Using Cellular Automata

The cellular automata （CA） micro-simulation model was used to describe the behavior of the mixed traffic flows at crosswalks where the pedestrians compete with the vehicles to cross the roadway. The focus of this paper is the behavior of pedestrians and the influence of pedestrians＇ behavior on the vehicle flow, pedestrian flows, and the vehicle waiting time. The proportion of pedestrians who do not obey traffic laws, the group effect, and expected waiting time of pedestrians, regarded as the most important pedestrian characteristics, are taken into consideration in the analysis. Simulation results show the ability of the microsimulation to capture the most important features of mixed traffic flow.