Two-lane Highways Research Articles

Identification and Comparative Safety Analysis of Overtaking Patterns on Two-Lane Highways: A Simulator Study With Novice Drivers

Overtaking on two-lane highways is one of the riskiest driving maneuvers. However, safety analysis technologies for overtaking patterns and trajectories require development. In this simulator study, 328 overtaking trajectories were collected from 52 novice drivers to analyze difference in overtaking safety performances on two-lane highways under different traffic conditions. Two analyses were conducted: Analysis I focused on structural trajectory differences and classified the trajectory sample into two patterns—“ladder” (LAT) and “triangle” (TRT). In Analysis II, a comparative safety evaluation method was established based on data envelopment analysis to compare overtaking pattern safety; a factor analysis of the safety performance was undertaken by means of ordinary regression models. We found that TRT had a lower spatial consumption and smoother trajectory than LAT, but drivers overtaking using TRT were exposed to higher risk than LAT. Certain environmental and human factors had an influence on the safety levels of the patterns: both deteriorated when drivers were surrounded by vehicles driving at higher speeds, and improved with longer passing sight distances. However, safety levels when overtaking trucks were significantly worse than overtaking cars in the LAT pattern—the opposite was found for TRT. Female drivers’ safety performance was superior in the LAT pattern; no significant gender difference were found with TRT. A longer following distance was found to ameliorate the safety of the TRT pattern, with no effect on LAT. These findings aid understanding of overtaking maneuvers on two-lane highways, and provide recommendations for advanced assistance driving and automatic driving systems.

Design and evaluation of cooperative human–machine interface for changing lanes in conditional driving automation

This study analyzes the impact of cooperative human–machine interface designs on drivers’ trust in and interaction with automated driving systems (ADSs) during lane changes on highways. While drivers’ inappropriate trust in ADSs can affect their behavior toward the system, capability to detect inadequate system performance, and perception of surrounding traffic disturbances, their engagement in the automated process can improve their comprehension of the system and traffic conditions, which is necessary for the safe practice of automated driving. Forty drivers practiced conditional driving automation in a driving simulator and encountered traffic congestion on the main lane of a two-lane highway. Four ADS designs were proposed to bypass the congestion. ADS-1 detects the congestion and synchronizes the speed accordingly. ADS-2 requests the driver to resume manual control and overtake the congestion. ADS-3 requests the driver to push a button to let the system overtakes the congestion automatically. ADS-4 overtakes the congestion automatically after informing the driver, while the driver can cancel it by pushing a button within 6 s. In all these conditions, driver intervention was optional. Although the drivers preferred and trusted ADS-1 and ADS-2 more than ADS-3 and ADS-4, the results indicate significant improvements in the driving performance and system usage under ADS-3 and ADS-4. Driving with ADS-3 improved drivers’ engagement and reduced the requirement for control transfer compared with other systems. However, the time headway between the subject and adjacent vehicles indicated that lane changes were more critical under ADS-3 and ADS-4 than ADS-1 and ADS-2. Such deficiency of alignment between driver perception and safe behaviors has implications for the design of future studies and systems that need to balance satisfaction and safety. These observations are likely to improve driver interaction with automated vehicles.

Modeling HDV and CAV Mixed Traffic Flow on a Foggy Two-Lane Highway with Cellular Automata and Game Theory Model

Mixed traffic composed of human-driven vehicles (HDVs) and CAVs will exist for an extended period before connected and autonomous vehicles (CAVs) are fully employed on the road. There is a consensus that dense fog can cause serious traffic accidents and reduce traffic efficiency. In order to enhance the safety, mobility, and efficiency of highway networks in adverse weather conditions, it is necessary to explore the characteristics of mixed traffic. Therefore, we develop a novel cellular automata model for mixed traffic considering the limited visual distance and exploring the influence of visibility levels and CAV market penetration on traffic efficiency. We design acceleration, deceleration, and randomization rules for different car-following scenes. For lane-changing, considering the interaction of CAVs and surrounding vehicles, we introduce game theory (GT) to lane-changing policies for CAVs. This paper presents the following main findings. In reduced visibility conditions, the introduction of CAVs is beneficial to improve mixed traffic efficiency on metrics such as free-flow speed and traffic capacity (e.g., 100% CAVs could increase the traffic capacity up to around 182% in environments of dense fog). In addition, the critical density increases as the proportion of CAVs increases, which is more pronounced in conditions of dense fog according to the simulation results. In addition, we compared the proposed GT-based lane-changing strategy to the traditional STCA lane-changing strategy. The results showed that the average speed is significantly improved under the proposed lane-changing strategy. The model presented in this paper can evaluate the overall performance and provide a reference for future management and control of mixed traffic flow in fog conditions.

Two-Lane Highways: Indispensable Rural Mobility

Two-lane highways refer to roadways consisting of two lanes in the cross section, one for each direction of travel. Occasionally, passing lanes may be added to one or two sides of the roadway extending the cross section to three or four lanes at those locations. In this entry, two-lane highways strictly refer to roads in rural areas meeting the previous definition and do not include urban and suburban streets.

Setting the speed limit for highway horizontal curves: A revision of inferred design speed based on vehicle system dynamics

An inferred design speed (IS) is the maximum vehicle speed for which all critical design speed-related criteria are met at a particular location, which is widely recognized as an important speed limit on highways. However, a side friction factor is used as an index for vehicle lateral stability in the calculation of IS for horizontal curves. This condition causes inaccuracies in the value of IS due to the incapability of the index in fully characterizing the steering stability and track-holding capability of vehicles. This paper aims to fill this gap by discovering the lateral instability modes of vehicles on horizontal curves and to determine the boundary of each index beyond which the corresponding mode of instability occurs. Thus, a theoretical framework for realizing a revised IS (RIS) was established. A high-precision seven-degree-of-freedom driver–vehicle–road mathematical model was developed using MATLAB/Simulink. The state of vehicle lateral instability on highway horizontal curves was decoupled, and the boundaries of vehicle stability indices were deduced using the theory of vehicle system dynamics. Accordingly, a procedure for determining RIS was proposed. Case studies were conducted on the three horizontal curves of a two-lane rural highway in China, and existing speed limit methods were compared with RIS. With in-depth consideration of the lateral instability characteristics of vehicles, RIS provides traffic management departments with a precise maximum safe speed on horizontal curves under various pavement friction conditions. It is expected to be a restriction with respect to safety for other speed limit strategies that consider driver expectancy and efficiency.

Assessing Driving Risk at the Second Phase of Overtaking on Two-Lane Highways for Young Novice Drivers Based on Driving Simulation

Overtaking on two-lane highways is a complex and multi-phase maneuver associated with high collision risk, especially for young novice drivers. Most of the relevant studies, however, focused mainly on the first phase, i.e., the lane-changing phase, such as willingness to overtake, while the second phase, i.e., the back-to-lane phase, has not been investigated systematically. It is a risky phase in which a driver faces the risk of collision with not only the approaching vehicle on the opposite lane but also the impeding vehicle at the original lane. In this study, by designing and conducting a driving simulator experiment, we assess the driving risk of 47 young novice drivers during their second phase of overtaking on two-lane highways. The time-to-collision (TTC) values at the two critical positions are calculated from a micro-geometric point of view, based on which a two-dimensional risk index is proposed and the fuzzy C-means clustering algorithm is applied to group all the samples and to assess their overtaking risk. Furthermore, a multi-class logistic model is developed to understand the potential factors related to the risky overtaking maneuvers at this phase. The results show that most of the young novice drivers cannot make accurate judgments during their second phase of overtaking. When turning back to the original lane, they are more likely to be aware of the opposite vehicle that is approaching them, while how to correctly avoid the collision risk with the impeding vehicle at this phase is probably a more critical issue for young novice drivers.

Location of Emergency Escape Ramps on Two-Lane Rural Highways Based on the Fuzzy Multicriteria Decision-Making Method

Today, the lack of practical research is one of the most important concerns worldwide, and location, which is an important issue in most projects, has received less attention from experts. In this study, the location criteria of emergency escape ramps were examined, and according to the Myers formula, the temperature-distance diagram along the route was obtained. Also, the speed of vehicles entering the escape ramp was examined according to the American Association of State Highway and Transportation Officials (AASHTO) in the proposed options that were obtained from the experts. Then, 3 general criteria and 16 subcriteria were classified, and finally, the importance of criteria was examined by the fuzzy analytic hierarchy process (F-AHP), and the high-priority options were illustrated using the fuzzy technique for order performance by similarity to ideal solution (F-TOPSIS). The proposed options were evaluated and prioritized for an emergency escape ramp on the two-lane rural highways of Salavat Abad village pass of Sanandaj city, Kurdistan Province, Iran. The results showed that the technical criteria with more than 69% among the general criteria and subcriteria of the percentage of longitudinal slope, longitudinal slope length, and vehicle design speed were the most important factors influencing the location of an emergency escape ramp. Moreover, among the proposed options, the four options 3, 4, 5, and 6 had the highest score, and option 6 (Kurkur turn (2)) was identified as the most priority location for implementing the emergency escape ramp.

Abundance and fate of glass microspheres in river sediments and roadside soils: Lessons from the Świętokrzyskie region case study (south-central Poland)

Traffic-related glass microspheres in fluvial and roadside soil settings were used as an indicator for the occurrence and extent of road dust as a source of emissions. Microspheres were found in sediments of two rivers, at a distance of approximately 25 km of the city of Kielce (south-central Poland). Their highest contents in sediments were recorded near street stormwater drains into the Silnica River flowing through the city. The study also showed no influence of local bridges on the spatial distribution of glass microspheres in the river deposits. In contrast, soils adjacent to a two-lane highway revealed the presence of microspheres as far as 60 m of the roadway. As opposed to other road dust components, which have commonly been applied in traffic contamination studies, glass microspheres were a good indicator for road dust contamination. Most microspheres showed diverse concentrations of all minor and trace metal(loid)s. The mean contents of As, Pb and Sb (n = 601) were: 0.003 wt%, 0.014 wt% and 0.010 wt%, respectively, and only in some microspherules these elements exceeded EU current/expected regulatory standard levels (0.02%/0.015% for each). Although generally considered to be non-toxic, silica rich microbeads might be the best proxy for non-exhaust particle matter discharged from the road traffic into the environment.

A novel lattice hydrodynamic model accounting for individual difference of honk effect for two-lane highway under V2X environment

In this work, the individual difference of the honk effect is explored on two lanes via traffic modeling of the lattice model under Vehicle to X (V2X) environment. We study the impact of individual difference corresponding to honk cases on traffic stability through linear stability analysis for a two-lane highway. Furthermore, the mKdV equation under the lane changing phenomena is conducted via nonlinear analysis. Simulation cases for the early time and longtime impact reveal that individual difference of driving characteristics has a distinct impact on two lanes under the whistling environment.

How to determine Safe Speed for negotiating Horizontal Curves with Restricted Sight distance on Two-Lane Highways in India?

How to determine Safe Speed for negotiating Horizontal Curves with Restricted Sight distance on Two-Lane Highways in India?

Design Consistency Evaluation of Two-Lane Rural Highways in Hilly Terrains

The main objective of the geometric design consistency is to minimize the emergence of unforeseen events when road users drive along a road segment. A consistent highway design ensures that successive geometric elements act in a coordinated way. In India, vehicles with diverse static and dynamic characteristics interact with each other leading to a significant difference in traffic flow operations compared to highways in developed countries. Due to the heterogeneity in traffic flow, geometric consistency would vary significantly by vehicle category for similar curve characteristics. The present study analyzes geometric design consistency by vehicle and develops vehicle category-based design consistency models for mixed traffic environments on two-lane rural highways in hilly terrain in India. A total of 30 curves with varying geometric characteristics located along the National Highway (NH-953) connecting Netrang and Rajpipla, Gujarat, India, were selected. Speed data were collected using radar gun for three vehicles category: motorized two-wheelers (MTW), cars, and heavy commercial vehicles (HCV). Geometric design consistency was evaluated using operating speed as a surrogate safety measure. The results showed that 38% and 10% of the curves (for cars), 51% and 20% of the curves (for MTW), and 32% and 51% of the curves (for HCV) have ratings of fair and poor consistency, respectively. Design consistency models for different vehicle categories were developed using the generalized linear regression modelling (GzLM) technique. The results showed that the deflection angle is positively correlated, whereas curve and tangent lengths are negatively correlated with highway alignment design consistency.

The Dynamic Evolution Integrating the Flux Limit Effect in Lattice Hydrodynamic Model for Two-Lane Highway

The Dynamic Evolution Integrating the Flux Limit Effect in Lattice Hydrodynamic Model for Two-Lane Highway

Original Research Paperestimation of Two-Lane Highway Capacity Based on Geometric Features in India

Original Research Paperestimation of Two-Lane Highway Capacity Based on Geometric Features in India

Lane-Offset Risk Evaluation for Two-Lane Highway Using 3d Laser Scanning System and Imu

Lane-Offset Risk Evaluation for Two-Lane Highway Using 3d Laser Scanning System and Imu

Overtaking risk modeling in two-lane two-way highway with heterogeneous traffic environment of a low-income country using naturalistic driving dataset

Introduction: Driver behavior related to overtaking maneuvers, which are considered a major safety risk determinant on two-lane two-way highway in low- and middle-income countries (LMIC), are an important subject of further analysis. This study evaluates safety risk in terms of nature and severity of probable conflicts during overtaking maneuvers on a bi-directional undivided two-lane highway in a heterogeneous traffic environment of a low-income country. Nature and severity of probable conflicts were defined with the application of surrogate safety proximity indicators in real-world naturalistic driving environment. Method: A risk severity model for overtaking maneuver was developed to better understand the significant factors associated with the probability of conflict and its severity during overtaking maneuver using discrete choice modeling approaches. The relevance of three alternate discrete outcome frameworks, namely multinomial logit (ML), ordered probit (OP), and mixed logit (MXL) models are addressed. The best fitted model is identified and estimated. The impact of the significant attributes was also evaluated. The study collected data from a section of two-lane highway in Bangladesh using naturalistic driving from both observational and computer vision techniques. A total of 46 explanatory variables related to overtaking maneuver are assessed. Results: Speed differential between overtaking and overtaken vehicles have a significant impact on the probability of severe conflicts. Moreover, the presence of a bus as an overtaking vehicle was found to contribute significantly to the severity of conflicts. Conclusions: The study makes substantial research contributions related to overtaking behavior and safety risk evaluation during overtaking in mixed traffic environment in low-income countries. The results can be used as a proactive tool for the evaluation of overtaking maneuvers and associated safety risk, and making policy decisions reducing safety risk during overtaking maneuver as well as overall safety, while acknowledging the limited resources and facilities in low-income countries.

Analysis of no-passing zones to assess the level of service on two-lane rural highways in Brazil

The highway capacity manual (HCM) is used to assess the level of service on two-lane rural highways in several countries, including Brazil. The 6th version of the HCM will address the capacity and level of service for two-lane highways based on follower density (FD). Studies have been conducted in Brazil to obtain a suitable method for calculating the level of service on two-lane highways. However, there are no studies that have determined the impact of no-passing zones involving FD, which is the main objective of this research. To achieve this goal, a set of traffic data was obtained from highway segments with the primary purpose of calibrating and validating the VISSIM traffic simulator used in this study. Using the simulator, traffic data were generated in hypothetical highway segments with a wide range of geometric and traffic characteristics. Traffic relationships for the simulation data were adjusted for the following conditions: (i) without no-passing zones, and (ii) with no-passing zones. The results of the analysis indicate that the models proposed in this study produce level of service and FD values close to values observed in the field.

A simulation-based empirical bayes approach: Incorporating unobserved heterogeneity in the before-after evaluation of engineering treatments

The Empirical Bayes approach for before-after evaluation methodology utilizing the negative binomial model does not account well for unobserved heterogeneity. Building on the Empirical Bayes approach, the objective of this study was to propose a framework to accommodate unobserved heterogeneity in before-after countermeasure evaluation. In particular, this study has proposed a simulation-based Empirical Bayes approach by applying the panel random parameters negative binomial model with parameterized overdispersion (PRNB-PO) to evaluate the effectiveness of engineering treatments. The proposed framework has been tested for the wide centerline treatment (WCLT) on rural two-lane two-way highways in Australia. The empirical analysis included 511 km of WCLT treated highways in a before-after evaluation within a time period of 2010 – 2018 and 430 km of reference sites in Queensland, Australia. The PRNB-PO models outperformed the traditional negative binomial models in terms of goodness-of-fit and prediction performance for total injury crashes, and fatal and serious injury (FSI) crashes. The simulation-based Empirical Bayes approach using the PRNB-PO model resulted in more precise estimates of crash modification factors than the standard Empirical Bayes approach. The WCLT is found to result in significant reductions in total injury crashes by 28.21% (95% confidence interval (CI) = 22.92 – 33.50%), FSI crashes by 13.90% (95% CI = 6.99 – 20.81%), and head-on crashes by 25.45% (95% CI = 14.87 – 36.03%). Overall, WCLT is an effective engineering treatment and should be considered a low-cost countermeasure on rural two-lane two-way highways.

Research on Truck Traffic Volume Conditions of Auxiliary Lanes on Two-Lane Highways

The larger the proportion of truck traffic volume, the greater the impact on traffic efficiency, and overtaking behavior will also have an impact. Therefore, in order to clarify the truck traffic volume of the freight two-lane highway due to the difficulty of overtaking, an actual vehicle test is carried out. This involves selecting the appropriate two-lane test section, recording each moment and speed in the driver’s overtaking behavior, performing multiple regression analysis to examine the relationship between the overtaking conflict time and design speed and traffic volume, determining a reasonable evaluation series of two-lane road overtaking risk and the corresponding overtaking conflict time threshold by the Fisher optimal segmentation method, and giving an overtaking behavior risk evaluation method based on conflict time. Finally, according to the overtaking conflict time model, different truck traffic conditions are obtained. The research results show that overtaking conflict time is negatively correlated with the traffic volume and design speed of the lane. Through the risk assessment of the corresponding overtaking behavior, the three levels of serious conflict, general conflict and non-conflict are determined, and the freight traffic volume corresponding to different conflict levels at different speeds is calculated, which provides a reference for setting auxiliary lanes for the two-lane freight highway.

Risk evaluation of multiple passing maneuvers on two-lane rural highways in Iran

The passing maneuver (PM) on two-lane rural highways is a very complicated driving task because it is associated with the risk of a head-on collision. It can be more risky for multiple PMs where a single vehicle passes at least two other ones. Using the time-to-collision (TTC) indicator, this paper addressed the risk of multiple PMs and developed a logistic regression model to predict the occurrence probability of a serious head-on conflict defined with a TTC of <3 sec-threshold. The effective accepted gap (EAG), passing duration, number of passed vehicles, and the end position of maneuvers were the explanatory variables and the data used to estimate the model were collected from 319 PMs using a drone at seven passing zones in Iran. Results indicated that 85% of the passing vehicles were safe in a single PM with EAGs greater than 22.4 sec for all types of passed vehicles. This safe EAG increased by up to 30.9 sec for vehicles involved in multiple PMs with two passed vehicles and 52 sec for those with three or more. Heavy vehicles required 3.1 sec more EAG than passenger cars to conduct a single PM and maneuvers ended in no-passing zones were more risky than those ending in a passing zone.

SPOT SPEED LIMIT STUDIES OF AGAIE-KATCHA-BARO ROAD AGAIE, NIGER STATE

The number of accidents in Nigeria increases relatively from year to year, despite the fact that there are many programs organized by the authority to reduce them. Several factors contribute to the occurrence of accidents. Some of which are human behavior, vehicles condition, weather conditions, road surfaces, and road alignments (vertical and horizontal curves). This research presents empirical research to estimate the 85th percentile operating speed limits. The speed data were obtained using a stopwatch on the selected location along the Agaie-Katcha-Baro Road Agaie, Niger State. Spot speed study was adopted as the method for the research. The method has successfully predicted the 85th percentile speed limit for the Agaie-Katcha-Baro Road Agaie, Niger State. It has established maximum and minimum speed limits for the road and has also shown how inexpensive and quick the stopwatch method is in conducting spot speed studies in Nigerian roads. The findings are hoped to provide a lasting solution towards the national design standard for the highway designer and planner to improving the consistency of geometric design elements of the two-lane highways.