Discretionary Lane Changing Research Articles

Fuzzy inference systems for discretionary lane changing decisions: Model improvements and research challenges

Lane Changing Decision Model (LCDM) is a critical component in semi- and fully-automated driving systems. Recent research has found that Fuzzy Inference System (FIS) is a promising approach to implementing LCDMs. To improve the FIS’s performance, this research reviewed the challenges in the development of a FIS model to make the yes,no decisions in discretionary lane changes. The FIS model was revised to bring its fuzzy inference rules more consistent with the fuzzy membership functions, and its composition and defuzzification methods more in line with the classical fuzzy logic theory. An equitable test data set with approximately equal number of yes,no data points was assembled from the same NGSIM data used in the past research. The test results proved that: (1) A LCDM’s performance was dependent on how the yes,no decisions in the test data set were manually labeled; and (2) Separating the fuzzy inference rules into a yes group and a no group and compute the results separately yielded potentially better decision accuracy. Furthermore, The Genetic Expression Programming Model (GEPM) performed better than the improved FIS-based model. The findings led the authors to suggest two possible research directions: (1) Add the subject vehicle’s speed as an input to the LCDM and redesign the decision-making model; and (2) Construct models for congested and uncongested traffic separately. The authors further suggested the use of instrumented vehicles to collect a set of high-fidelity lane changing data in the naturalistic driving environment. (word count: 246)

Platoon-aware cooperative lane-changing strategy for connected automated vehicles in mixed traffic flow

The platooning management technology for Connected Automated Vehicles (CAVs) can potentially increase the efficiency of the traffic system. However, the randomness in the spatial distribution of CAVs poses a new challenge for CAVs’ platooning strategy in mixed traffic flow. To effectively utilize the advantages of platooning technology, this paper proposes a platoon-aware cooperative lane-changing (PCLC) strategy inspired by platoon formation. This strategy focuses on the formation of CAV platoons in mixed traffic flow and restructures the spatial distribution of CAVs on the road segment. First, the cooperative lane-changing behavior of CAVs is modeled based on vehicle-to-vehicle communication, and a gap suitable for lane-changing is created by controlling the acceleration of cooperative CAVs to complete the lane-changing process smoothly. Meanwhile, considering the maximum platoon size, a decision-making framework of cooperative lane-changing for CAVs is designed. Then, considering the change in spatial distribution of CAVs (i.e., platoon intensity) caused by PCLC, the impact of PCLC on traffic capacity is analyzed from theoretical and numerical verification perspectives. Finally, simulation experiments are conducted to investigate the impact of PCLC on lane-changing indicators, traffic flow stability, and traffic efficiency. The simulation experiments show that compared with the discretionary lane-changing (DLC) operation, the PCLC strategy may reduce the lane-changing rate and raise the average platoon size on road segments, increasing road capacity. In addition, the vehicles on the road segment have modest swings in average speed and acceleration, proving the safety and stability of the proposed strategy. Particularly, scenarios with moderate to heavy traffic flow and fairly balanced CAVs penetration rates favor the effectiveness of this strategy. With 50% CAVs and moderate traffic density, the lane capacity increases by 450 veh/h and improves by 10.135%. These findings support the ability of PCLC strategy to reduce traffic congestion and effectively explore traffic management strategies for mixed traffic flow.

A decision model based on gene expression programming for discretionary lane-changing move

ABSTRACT This study focuses on modeling Discretionary Lane-Changing (DLC), which accounts for the majority of lane-change moves in traffic flows. A binary decision model for lane-changing moves was improved with the method of Gene Expression Programming (GEP). The decision to prefer GEP is due to its high performance in a variety of engineering solutions in the literature. The GEP model was trained with Next Generation SIMulation (NGSIM) trajectory data gathered at the I-80 Freeway in Emeryville, California, and then tested with data gathered at the U.S. Highway 101 in LA, California. The test results indicate that the model made decisions of “change lane” with 92.98% accuracy, and “do not change lane” with 99.65% accuracy. A sensitivity analysis was also conducted to discover potential limits of the performance of the GEP model. The performance of this model was compared with other high-performance decision models developed with the NGSIM's DLC data in the literature and with TransModeler's gap acceptance model. This comparison indicates that the GEP model is the most successful decision model for discretionary lane-changing moves. The GEP model has a high potential to be applied in DLC decision support systems in (semi-) automated vehicles, as well as traffic simulation software.

Analysis of discretionary lane-changing behaviours of autonomous vehicles based on real-world data

This study aims to quantify the impact of discretionary lane-changing (DLC) on following vehicles (FVs) in the target lane using real-world dataset. The Waymo Open Dataset is used to identify the differences between autonomous vehicles (AVs) DLC and human-driven vehicles (HDVs) DLC maneuvers and compare their impacts on the driving volatility. Then, a block maxima (BM) model is applied to estimate crash risks. Finally, multivariate adaptive regression splines (MARS) is adopted to model gap acceptance behaviors of AV and HDV. Compared to HDV DLC, AV DLC leads to lower speed and yaw rate volatility and smaller acceleration rates of FVs. Further, the BM model reveals that the crash risk in AV DLC events is half of that in HDV DLC events. Additionally, MARS show that AV and HDV accept different lead gap. These findings highlight the benefits of mixing AVs in traffic and guide the improvement of AV controllers.

Pricing lane changes

Risky and aggressive lane changes on highways reduce capacity and increase the risk of collision. We propose a lane-changing pricing scheme as an effective tool to penalize those maneuvers to reduce congestion as a societal goal while aiming for safe driving conditions. In this paper, we first model driver behavior and their payoffs under a game theory framework and find optimal lane-changing strategies for individuals and their peers in multiple pairwise games. Payoffs are estimated for two primary evaluation criteria: efficiency and safety, which are quantified by incorporating driver tradeoffs. After that, the discretionary lane-changing (DLC) model is calibrated and validated by real-world vehicular trajectory data. To manipulate drivers’ DLC behaviors, two types of lane-changing tolls based on local-optimal and global-optimal rules are introduced to align individual preferences with social benefits. We find prices can close this gap and achieve ‘win-win’ results by reducing drivers’ aggressive lane changes in the congested traffic. Meanwhile, the tolls collected can be used to compensate drivers who get delayed when yielding, to encourage appropriate yielding behavior and a pseudo-revenue neutral tolling system.

The Impact of a Single Discretionary Lane Change on Surrounding Traffic: An Analytic Investigation

As one of the most frequently occurred driving behaviors, the lane-changing’s impact on surrounding traffic is important. From the aspect of macro-traffic flows, its impact on traffic efficiency and safety has been investigated. However, as a non-essential lane-changing type, a single discretionary lane-changing’s impact on surrounding traffic is still difficult to be quantified by real-word traffic data. To solve this problem, this paper first proposes a trajectory data-based analytic method to calculate response time of the lane-changing vehicle and its following vehicles, then develops a time sequence data processing method based on feature points to analyze the change pattern of the variable minimum space, and then a lane-changing’s temporal and spatial on surrounding traffic can be captured by the decreasing-increasing pattern of minimum space. Besides, a high-precision trajectory data set, called Zen-traffic, is employed to demonstrate the effectiveness of the proposed methods and reach conclusions. Given the condition that the speed of a discretionary lane-changing vehicle is between 6 to 20 m/s, i.e., the traffic condition at which lane changes more likely occur, the results of the paper include (1) on average, 4 or 5 vehicles are usually impacted by a discretionary lane change; (2) the average impact time is 12 to 13 seconds and it has little relationship with the distance between the lane-changing vehicle and the following vehicle on the target/initial lane; (3) the lateral movement direction (i.e., changing to left or to right) of a lane change has a significant impact on the number of the vehicles affected.

Analyzing work zone effects on vehicular flow on an annular freeway with a tunnel

This paper develops a three lane continuum model to analyze the effects of a work zone on vehicular flow on an annular freeway with a tunnel. The model expresses the mandatory lane changing rate just upstream of the work zone in an explicit algebraic form with the relevant random parameter generated from golden section analysis, and describes the discretionary lane changing rate between adjacent lanes with a lane changing time depending on local traffic flow density and relaxation time. It is assumed that the annular freeway has three lanes, a work zone with a length of 0.2 km and lane II completely blocked, an upstream tunnel of 1.5km long, and an initial jam between the tunnel and work zone. The three lane continuum model is applied in vehicular flow simulation with a 3rd order accuracy numerical scheme. Numerical results also indicate that golden section application in the analysis of work zone effects is helpful in obtaining density thresholds of traffic jam formation, the time averaged traffic speed through the tunnel, dependencies of mean travel time, and vehicle fuel consumption on the initial density normalized by jam density. Numerical results reveal that there are two density thresholds of traffic jam formation, if both density thresholds are normalized by traffic jam density, the first threshold relating to the work zone is 0.14, while the second depending on the tunnel is 0.21. In the absence of a work zone, the mean travel time through lane I is slightly longer than that estimated for cases with a work zone. As soon as initial density is above the second threshold, the time averaged speed through the tunnel is 31.91 km/h, which agrees well with published data.

Modeling bounded rationality in discretionary lane change with the quantal response equilibrium of game theory

The primary purpose of discretionary lane change is to provide a speed advantage or a better driving environment. Game theory is one way to find each driver's most reasonable behavior plan by studying their competitive lane-changing behavior. Nash equilibrium provides an effective strategy to ensure the lane-changing vehicle can reach the maximum value of its expected returns. Other vehicles in the game also follow this strategy. However, due to the inadequate understanding of the driving environment and drivers’ physiological and psychological factors, it is difficult to have the entirely rational conditions required by Nash equilibrium, whose solution is usually quite different from the actual result. To quantify drivers’ rationality in lane-changing decisions, we established a model of bounded rationality based on the quantal response equilibrium (QRE), in which drivers are not perfect optimizers and face uncertainty in other drivers’ actions. The maximum likelihood estimation and data analysis from NGSIM confirm that drivers in discretionary lane-changing games exhibit bounded rationality. As the lane-changing decision continues, drivers become more aware of their surroundings to be more rational. More than 91.5% of our model predictions are in line, which means our QRE model can effectively describe discretionary lane-changing decision behavior. Compared to Talebpour's game model, our model has a stronger predictive ability and can more accurately describe discretionary lane-changing behavior.

Investigating lane-changing moves of vehicles departing from signalized junction

ABSTRACT Discretionary Lane-Changing (DLC) possesses different characteristics under various traffic conditions. Therefore, in order to model DLC moves in the correct manner, they need to be approached separately for various conditions. This study has examined the DLC moves of vehicles, which depart from signalized junction. It is observed that a large number of vehicles move to a neighboring lane in order to travel under better traffic conditions, after the traffic lights turn green. There are many parameters, which motivate the vehicles to change lanes at this stage. This study has focused on discovering these parameters. Data was collected through field work for this purpose. Thereinafter, the impact value of each parameter has been discovered using four separate feature selection methods and has been sorted. Fuzzy Cognitive Maps have been developed with the obtained impact values. The models have been validated using the field data and have been compared with each other.

A comprehensive lateral motion prediction method of surrounding vehicles integrating driver intention prediction and vehicle behavior recognition

In order to solve the accuracy problem of the future motion prediction of the surrounding vehicles with different types of drivers, this paper proposes a comprehensive lateral motion prediction method that combines driver intention prediction and vehicle behavior recognition. For different drivers, different driver optimization models are established: personal optimal model and system optimal model. Then, the driver’s intention prediction probability is obtained through the game theory. Different from the traditional game theory, we apply different model for different driver on the premise of getting the type of driver instead of using the Nash equilibrium for all players. According to the results of driver intention prediction and the vehicle behavior recognition, the optimized polynomial trajectory is used to obtain the driver’s intention prediction trajectory and the vehicle behavior recognition trajectory. Next, the Nash-optimization function of the intention prediction trajectory and the behavior recognition trajectory are established respectively according to the trajectory error, and the balance between the two is our comprehensive trajectory. In order to verify the effectiveness of the proposed method, we conducted simulations under mandatory lane changing and discretionary lane changing conditions. The simulation results show that our algorithm can accurately predict the future motion of the vehicle under different drivers, different speeds and different gaps between vehicles. Its prediction performance is much better than other algorithms.

Unraveling Gap Selection Process During Discretionary Lane Changing by Vehicle Class

This paper studies and compares the gap selection process of multiple vehicle classes (passenger cars, delivery vans, and trucks) within their discretionary lane changing activities. Given a trajectory or a sequence of gap selection decisions, we aim to predict whether a vehicle will change or keep a lane. For this purpose, we use a large trajectory dataset, collected for the Netherlands, consisting of 3,647 trajectories of passenger car drivers, 1,080 trajectories of delivery van drivers, and 2,226 trajectories of truck drivers. We apply gated recurrent unit neural networks to separately model their gap selection processes. These three models can not only handle class imbalance but also capture long-term interdependencies. The models can predict gap selection of three vehicle classes with geometric mean accuracies of 84% or higher. To obtain insights into their gap selection processes, we apply a gradient-based technique to analyze what neural networks have learned. Our results suggest that there exist significant differences between vehicle classes in terms of the importance of historical information and features. Trucks seem to value a relatively long period, recent 6 seconds, of driving experience to select gaps compared to passenger cars and delivery vans. In addition, the perception of road topology seems to be a significant factor for delivery vans and trucks, contrary to passenger cars which highly value their kinematic features and interactions with surrounding vehicles, to select gaps. These insights offer a novel contribution towards better understanding and modeling of the driving behavior of multiple vehicle classes.

Characteristics of Heavy Vehicle Discretionary Lane Changing Based on Trajectory Data

A comprehensive analysis of the motivations, gap acceptance, duration, and speed adjustment of heavy vehicle lane changes (LC) is conducted in this paper. An rich data set containing 433 discretionary LC trajectories of heavy vehicles is used in this study and the data set is divided into two data sets based on the LC direction (LC to the left lane [LCLL] and LC to the right lane [LCRL]) for comparison. It is seen that LCLL and LCRL have significantly different motivations, which also results in different gap acceptance behavior. However, the LC direction does not significantly influence the LC duration. The navigation speed significantly influences the LC duration of heavy vehicles and the LC duration will decrease with the increase of speed, indicating the substantial impact of traffic conditions on LC duration. An obvious speed synchronization phenomenon is found in the process of LCLL, which is not the case in LCRL. The results of this study highlight the distinct characteristics of the LC of heavy vehicles and produce a better understanding of the lane-changing behaviors of heavy vehicles. The fitted distributions of LC duration and further investigation into gap acceptance behaviors may be used for microscopic traffic simulation and auto driving.

Connectivity analysis of V2V communication with discretionary lane changing approach

Connectivity analysis of V2V communication with discretionary lane changing approach

CLACD: A complete LAne-Changing decision modeling framework for the connected and traditional environments

This study develops a Complete LAne-Changing Decision (CLACD) modeling framework that explains both the mandatory and discretionary lane-changing behaviors, incorporates both the successful and failed lane-changing attempts, and describes lane-changing behaviors in both the traditional and connected environments. The connected environment provides real-time and valuable information about surrounding vehicles and downstream situations (e.g., congestion ahead) that drivers cannot foresee. Such information can be particularly useful for complex driving maneuvers like discretionary lane-changing (DLC), which requires information about surrounding traffic speeds and subsequent gaps available on the adjacent lanes. DLC modeling efforts in the connected environment appear to be nascent, primarily because of: (a) the novelty of the connected environment (and the consequent scarcity of the relevant data), and (b) the lack of a behaviorally sound DLC model even for the traditional environment (that is, without driver-aid messages). Moreover, the existing models omit failed DLC attempts by motorists that are likely to create traffic disruptions and have a significant impact on traffic safety. To overcome these challenges, this study develops a DLC model (i.e., CLACD model) for the traditional environment, which is extended for the connected environment. An integrated approach is employed to model DLC behavior by combining the target lane selection using the utility theory approach and the gap acceptance behavior using a game theory approach. To collect high-quality vehicle trajectory data in the connected environment, the CARRS-Q advanced driving simulator was used. The CLACD models (for both the traditional and connected environments) are calibrated using NGSIM and the driving simulator data, and the CLACD models’ performances were rigorously assessed using various performance indicators. Results reveal that the CLACD models can effectively capture the observed DLC decisions with high accuracy. The performance of CLACD models is compared with the performance of two alternative models described in the literature, revealing that the CLACD models outperform the alternatives. A sensitivity analysis suggests a consistent trend of the CLACD models, which agrees with past research. Furthermore, the CLACD model shows a realistic prediction of traffic flow patterns compared with the utility theory model. By incorporating failed DLC attempts into the CLACD models, the performance and realism of CLACD models have been significantly improved.

The dynamic tradeoff between safety and efficiency in discretionary lane-changing behavior: A random parameters logit approach with heterogeneity in means and variances

The discretionary lane-changing behavior is highly associated with crash occurrence. This paper investigates the dynamic tradeoff between safety and efficiency and influencing factors of the decision-making process for the discretionary lane-change. A random parameters logit approach with heterogeneity in means and variances is employed on a microscopic vehicle trajectory dataset. Four vehicles are analyzed as a discretionary lane-changing group, and both the distance-related and speed-related factors are taken into account to examine their dynamic effects. The modeling results indicate that (1) two distance-related variables produce significant random parameters with heterogeneity in means and variances, while there is only one speed-related variable having significant result for heterogeneity in means and variances; (2) the relationship between the speed of lane-changing vehicle and the heterogeneity in mean of vehicle clearance distance between leading vehicle in current lane and lane-changing vehicle quantitatively demonstrates that when the driver decides whether to change lanes, the driver considers the tradeoff between distance (i.e., safety) and speed (i.e., efficiency) at the same time; and (3) the number of significant variables is gradually decreased during the lane-changing decision-making process. It demonstrates that the lane-changing decision is a dynamic process where drivers gradually select more critical factors and pay more attention to them.

Modeling Lane-Changing Behaviors in Merging Areas of Urban Expressways in Nanjing, China

Merging bottlenecks in urban expressways have attracted much attention in recent years. In this paper, vehicular mandatory lane-changing (MLC) data are collected from Yingtian Avenue in Nanjing, China using cameras. Based on a series of video processing algorithms, 656 MLC behaviors of 1,560 vehicles are extracted from videos. A logistic regression model is proposed to depict MLC at the merging bottleneck and estimate the possibility of accepting gaps for merging, which is validated by precision testing and simulation. During the simulation, a discretionary lane-changing (DLC) model is utilized and calibrated to describe vehicular DLC behaviors for the sake of consistency and completeness. Finally, by simulating different arrival rates of mainline and ramp, a linear regression model is built to predict breakdown at merging bottlenecks. According to data analysis, the MLC model represents high precision during the decision-making process. Besides, the breakdown prediction model implies strong correlation between traffic demand and breakdown occurrence.

Understanding the discretionary lane-changing behaviour in the connected environment

Discretionary lane-changing (DLC) is one of the complex driving manoeuvres that requires surrounding traffic information for efficient and safe manoeuvring. The connected environment not only provides such information but also increases situational awareness, which is useful for DLC decision-making. However, the literature is devoid of any concrete evidence of such impact of the connected environment on DLC decision-making. As such, this paper analyses the effects of the connected environment on DLC behaviour. Seventy-eight participants from a diverse background performed DLCs in randomised driving conditions using the CARRS-Q advanced driving simulator. These driving conditions are: baseline (without driving messages), connected environment with perfect communication (fully functioning and uninterrupted supply of driving messages), and connected environment with communication delay (impaired communication). Various key driving behaviour indicators are analysed and compared using a linear mixed model. To analyse the effects of the connected environment on DLC decision-making, two Generalised Estimation Equation (GEE) models are developed for gap acceptance and DLC duration. In addition, a Weibull accelerated failure time hazard-based duration model is developed to investigate the impact of the connected environment on safety associated with DLC manoeuvres. We find that drivers in the connected environment have a larger spacing, larger lead and lag gaps, a longer DLC duration, and a lower acceleration noise compared to the baseline condition. The GEE model on gap acceptance reveals that drivers tend to select relatively bigger gap sizes when the connected environment offers them the subsequent gap information. Similarly, the GEE model for DLC duration suggests that the connected environment increases DLC durations by 2.22 s and 2.11 s in perfect communication and communication delay driving conditions, respectively. Finally, the hazard-based duration model provides insights into the probability of avoiding a lane-changing collision, and indicates that the probability of a lane-changing collision is less in the connected environment driving conditions than in the baseline scenario. Overall, the connected environment improves the DLC driving behaviour and enhances traffic safety.

Research on Decision-Making Behavior of Discretionary Lane-Changing Based on Cumulative Prospect Theory

In this paper, the decision-making model of discretionary lane-changing is established using cumulative prospect theory (CPT). Through analyzing the vehicles’ dynamic running states, safety spacing calculating approaches for discretionary lane-changing and lane-keeping have been put forward firstly. Then, based on CPT, a lane-changing decision model with accelerating space as its utility is proposed by estimating the difference between actual spacings and the safety spacings for discretionary lane-changing as well as lane-keeping. In order to calculate the utility of discretionary lane-changing, dynamic reference points and a parameter representing driver’s risk preference are introduced into the model. With the real data collected from an urban expressway, the distribution of discretionary lane-changing duration is analyzed, and the model parameters are also calibrated. Furthermore, the applicability of the model is evaluated by comparing with the actual observation and random unity model. Finally, the sensitivity analysis of the model is carried out, that is, assessing the influence degree of each variable on the decision result. The study reveals that the CPT-based model can describe discretionary lane-changing behavior more accurately, which consider drivers’ risk-aversion during decision-making.

A predictive model of discretionary lane change behavior considering human factors in the framework of time parameters

Lane changing is regarded as one of the most challenging behaviors of drivers. The lane-changing behaviors are divided into mandatory and discretionary. This study proposes an adaptive neuro-fuzzy model of discretionary lane-changing behavior in real traffic flow. Similar to other behaviors of drivers, lane changing is influenced by human factors, including age, gender, level of driving experience, hastiness, cautiousness, and alertness as well as environmental factors such as road and weather conditions. Identifying and measuring the said factors seem to be difficult or, in some cases, impossible. This study sorts out the lane-changing behavior into moments and two time intervals. In these time intervals, distance and relative speed, affected by the said factors, are accounted for in terms of time parameters and fed as inputs to the proposed predictive model. This is the innovative and distinguishing feature of the present study when compared to other researches. Finally, simulation and comparison based on real data indicate that when time parameters are considered and fed as inputs to model the error between the driver’s behavior and the proposed predictive model is less than when time parameter is not accounted for.

Route Control Strategies for Autonomous Vehicles Exiting to Off-Ramps

This paper proposes three route control strategies for autonomous vehicles (AVs) exiting to off-ramps. First, two microscopic lane-changing models are developed to simulate the off-ramp behaviors for AVs. A risk factor $\lambda $ is introduced in the discretionary lane-changing (DLC) model, and a five-step process is developed for the mandatory lane-changing (MLC) model. Second, three route control strategies are presented, i.e., grading strategy (GS), half-overlap strategy (HOS), and full-overlap strategy (FOS). Finally, the extensive numerical simulations are conducted to analyze the characteristics of each strategy based on the MATLAB platform. The results indicate that the studied area displays significant variability in spatiotemporal dynamics of average velocity and road capacity under different strategies. It is found that the GS is the most effective control strategy for traffic congestion dissipation and travel delay reduction, followed by the HOS and, then, the FOS. The road capacity under the GS is increased by 19.1% and 7.8% compared to the FOS and the HOS, respectively. Furthermore, the GS consumes lower costs in terms of safety, travel efficiency, and route and lane switch frequency compared to the HOS and FOS, which is verified as the optimal strategy according to overall running cost. The findings of this paper can provide useful references for the design of AVs as well as the management of the automated highway systems.