Curved Road Sections Research Articles

Inclusive assessment of road traffic accident associated with design-construction disparities and contemplating its relative impact for sustainable road safety

Purpose Road accident is a major threat to sustainable road safety, causing immense suffering and posing an increasingly serious global challenge, especially in developing countries. It is the leading cause of death, injuries and property damage. While vehicle driver-related factors play a significant role in accidents, poorly designed and constructed roads are also a growing factor. As result, this study aims to assess traffic accident problems associated with design-construction complications on Arba Minch-Jinka Road, Ethiopia. Design/methodology/approach From 2013 to 2021, a large amount of traffic accident data was gathered, and through actual roadway surveys at potential locations along the road, the data was associated with design-construction parameters. The analysis was done by adopting descriptive statistics incorporating comparative hypotheses, in which the individual and combined effects of design-construction issues were identified. Results revealed, on average, 76% of total coincided accidents along the study road were associated with design-construction issues. Exclusively, causing factors, i.e. roadway, driver, vehicle, pedestrian problems and environmental, contributed 7.65%, 77.78%, 6.17%, 6.05% and 2.35% traffic accidents, respectively. Findings Detailed and time-consuming data collection, investigations, analysis and assessments were used in the research to discover a strong association between road design-construction problems and traffic accidents. As a result, 42 black spot sections were identified, and 7.65% is exclusively caused from design-construction problems. Curved road sections led the surge by 42% from selected design-construction variable, whereas the remaining 58% was shared among four parameters. According to relative analysis, design-construction issues caused a 58.17%, 12.14%, 32.36% and 29.93% increase in accidents in combination with driver, vehicle, pedestrian and environmental factors, respectively. This is in an average of 33.15% escalated problem in a combination that raises questions about the sustainability of road safety. Originality/value It is essential to use scientific methodologies to evaluate traffic accidents and associated design-build discrepancies in developing nations like Ethiopia if we are to achieve sustainable road safety. The fundamental importance and value of this study is that it promotes accountability to the road design and construction, which are not frequently thought of as influencing factors in traffic accidents. This paper is original, and all references have been correctly mentioned, to the best of the author’s knowledge.

Critical radius prediction for small radius curved section of two-lane secondary highways based on speed characteristics

Small radius curved sections of two-lane secondary highways have low technical indicators, complex alignments, and frequent accidents. In order to improve the safety of traffic operation, the article investigates the curved sections of two-lane secondary highways with different radii and obtains the travelling speeds of different vehicle types at different section locations. By studying the trajectory characteristics and speed characteristics of vehicles travelling in curves, the velocity difference ratio, which responds to the continuity of driving speed, was defined. Then, based on this, this paper investigates the vehicle motion law of small radius curved road sections. The results show that the speed change of large cars in small radius curves is similar to a “U" shape, while the speed change of small cars is similar to a “V" shape. The speed adjustments of the larger cars occur mainly within the range of gentle curves, whereas the speed changes of the smaller cars are large throughout the range of curves. There is a significant exponential function relationship between curve radius and 85 % percentile speed, from which the curve radius threshold can be predicted. This provides a basis for engineering construction of curved road sections and optimization of curve design indicators, which greatly improves the traffic safety level of curved road sections.

Impact of freeway slope photovoltaic panels on drivers: A study based on driving simulator

Aiming at the impact of freeway slope photovoltaic construction on driving safety, a driving simulator experiment was carried out. By designing eight slope photovoltaic schemes under varying sunlight conditions and road alignment parameters, we recruited 35 drivers to collect detailed driving behavior data. Seven driving indicators were selected to develop an evaluation index system. Statistical analysis was conducted to compare driver behavioral performance under eight slope photovoltaic schemes. The findings reveal that the installation of photovoltaic panels on freeway slopes significantly affects driving behavior. Specifically, the driver's speed and degree of steering wheel angle decreased significantly, while acceleration increased significantly on straight alignment. The standard deviation of driver speed, acceleration and standard deviation of acceleration significantly reduced, while the degree of steering wheel angle and the depth of the gas pedal significantly increased when photovoltaic panels were laid on the side slopes on curved road sections. In addition, different curve radius, the impact of photovoltaic panels on acceleration and degree of steering wheel turning angle were different. There is a significant effect of installing side slope photovoltaic panels on driver acceleration, standard deviation of acceleration and degree of steering wheel turning angle in curved sections with different curve radius. Under different sunlight conditions, the impact of photovoltaic panels on the degree of steering wheel angle were also different. The actual setup needs to take into account the impact of different road alignments on drivers. The is study provided theoretical support for the installation of freeway slope photovoltaic panels.

The Influence of the Relative Motion Dynamics of the Wheeled Vehicle Sprung and Unsprung Part on the Motion Stability along Curved Road Sections

The research method of the influence of the main suspension parameters on the motion stability of a wheeled vehicle was developed on the basis of a flat model of the dynamics of its relative motion. The mathematical model is a system of two nonlinear differential equations of the second order. The basic parameters of transverse angular oscillations of the sprung and unsprung part, which determine the dynamics of relative motion, are described using the basic principles of the perturbation method in combination with Ateb-functions. Kinetostatic equations and conditions of motion stability in the aggregate made it possible to determine the critical value of the steady motion speed as a function of the main parameters that characterize the suspension and the oscillations amplitudes of the sprung and unsprung part.It was established that an increase in the oscillations amplitude of the unsprung part from 0.01 rad to 0.015 rad causes a decrease in the critical speed of steady motion by up to 35%.The main results can serve as a basis for the suspension modernization of wheeled vehicle, and their reliability is confirmed by obtaining, in the extreme case, known results concerning suspensions with linear characteristics of elastic elements and damping devices

Analysis of Operating Safety of Tractor-Trailer under Crosswind in Cold Mountainous Areas

To investigate the driving safety of tractor-trailers under extreme conditions in cold mountainous areas, this paper used numerical simulation software to construct a driving scenario of cold mountainous road, to simulate and analyze the driving safety of tractor-trailers under different wind speed and driving speed conditions, and then the critical deriving speed for safe driving was obtained. Four main factors were considered: low adhesion coefficient, strong crosswind, road radius, driving speed, lateral acceleration, and vertical load-deflection rate (LTR) were selected as the main safety response indexes for the determination of sideslip and rollover. The results show that strong crosswinds have an obvious effect on the tractor-trailer sideslip, and the safe operating speed range of the tractor-trailer is from 0 to 30 km/h, with the value of safe driving speed decreasing as the wind speed increases; the speed range where sideslip occurs is from 30 to 37 km/h, with the dangerous driving speed also decreasing as the wind speed increases; accidents when the driving speed exceeds 38 km/h. In addition, simulation experiments show that tractor-trailers generally skid first without rollover on a combination of curved road sections with a low coefficient of adhesion and super-elevation. Finally, the driving simulator was used to test the driving conditions of the tractor-trailer on the cold curved slope combination section with different crosswind speeds, and the experimental results proved the validity of the simulation’s safe speed threshold.

Multi-Target Tracking Algorithm Combined with High-Precision Map

On high-speed roads, there are certain blind areas within the radar coverage, especially when the blind zone is in curved road sections; because the radar does not have the measurement point information in multiple frames, it is easy to have a large deviation between the real trajectory and the filtered trajectory. In this paper, we propose a track prediction method combined with a high-precision map to solve the problem of scattered tracks when the targets are in the blind area. First, the lane centerline is fitted to the upstream and downstream lane edges obtained from the high-precision map in certain steps, and the off-north angle at each fitted point is obtained. Secondly, the normal trajectory is predicted according to the conventional method; for the extrapolated trajectory, the northerly angle of the lane centerline at the current position of the trajectory is obtained, the current coordinate system is converted from the north-east-up (ENU) coordinate system to the vehicle coordinate system, and the lateral velocity of the target is set to zero in the vehicle coordinate system to reduce the error caused by the lateral velocity drag of the target. Finally, the normal trajectory is updated and corrected, and the normal and extrapolated trajectories are managed and reported. The experimental results show that the accuracy and convergence effect of the proposed methods are much better than the traditional methods.

НЕЛІНІЙНІ ПОПЕРЕЧНО-КУТОВІ КОЛИВАННЯ ПІДРЕСОРЕНОЇ ТА НЕПІДРЕСОРЕНОЇ ЧАСТИН КОЛІСНИХ ТРАНСПОРТНИХ ЗАСОБІВ ТА ЇХ ВПЛИВ НА СТІЙКІСТЬ РУХУ

A method of analytical study of the nonlinear transverse-angular oscillations influence of the sprung-unsprung part system on the traffic stability of a wheeled vehicle along curved road sections has been developed. A system of nonlinear differential equations describing the dynamics of the relative motion of this system has been obtained and a first approximation of its analytical solution has been constructed. The peculiarity of the oscillations of the specified parts is that their natural frequencies depend on the amplitudes. Therefore, the dynamic interaction between the sprung and unsprung parts, as well as the road surface and elastic tires are determined by the vibrations amplitude-frequency characteristics of the specified parts, which are caused by road irregularities. Using the kinetostatics equation of the unsprung-sprung part system, the forces of dynamic interaction of elastic wheels with the road surface were determined – the basic ratios for evaluating traffic stability. It has been established: the relative oscillations of the sprung and unsprung parts of a vehicle significantly reduce the critical speed values of stable motion for overturning; the critical speed value of stable motion for overturning is greater for larger static deformation values of elastic shock absorbers and tires, as well as the progressive characteristic of elastic shock absorbers. The obtained main results can serve as a basis for the creation of a software product of adaptive suspensions, and their reliability is confirmed by obtaining results in the extreme case, which apply to simpler - linear calculation models of vehicle dynamics.

Permitted speed decision of single-unit trucks with emergency braking maneuver on horizontal curves under rainy weather.

Under adverse weather conditions, visibility and the available pavement friction are reduced. The improper selection of speed on curved road sections leads to an unreasonable distribution of longitudinal and lateral friction, which is likely to cause rear-end collisions and lateral instability accidents. This study considers the combined braking and turning maneuvers to obtain the permitted vehicle speed under rainy conditions. First, a braking distance computation model was established by simplifying the relationship curve between brake pedal force, vehicle braking deceleration, and braking time. Different from the visibility commonly used in the meteorological field, this paper defines "driver’s sight distance based on real road scenarios" as a threshold to measure the longitudinal safety of the vehicle. Furthermore, the lateral friction and rollover margin is defined to characterize the vehicle’s lateral stability. The corresponding relationship between rainfall intensity-water film thickness-road friction is established to better predict the safe speed based on the information issued by the weather station. It should be noted that since the road friction factor of the wet pavement not only determined the safe vehicle speed but also be determined by the vehicle speed, so we adopt Ferrari’s method to solve the quartic equation about permitted vehicle speed. Finally, the braking and turning maneuvers are considered comprehensively based on the principle of friction ellipse. The results of the TruckSim simulation show that for a single-unit truck, running at the computed permitted speed, both lateral and longitudinal stability meet the requirements. The proposed permitted vehicle speed model on horizontal curves can provide driving guidance for drivers on curves under rainy weather or as a decision-making basis for road managers.

Automotive Safety Rolling Barrier

The government is always looking at the latest technology that can ensure safety of road users, as outlined in the construction industry transformation plan. A small Korean manufacturing company invented a new concept longitudinal barrier, (The Rolling Barrier) which had continuous pipes covered with urethane rings. This study aims to evaluate the effectiveness of the “Rolling Barrier” and to understand the Rolling Barrier’s characteristics of crash cushioning, how to correct the vehicles running direction and the required strength of barriers. They convert that impact energy into rotational energy to propel the vehicle forward rather than potentially breaking through an immovable barrier. When a car hits the barrier, the rotating barrel converts shock from the vehicle to rotational energy. Upper and lower frames adjust tires of large and small vehicles to prevent the steering system from a functional loss. The Rolling Barrier can be effectively used in curved roads sections, ramps, medians and entrance or exit ramps in parking garages. In this paper, the description and studies of Rolling Barriers are elaborated. In 2015, there were 63,805 traffic accidents over on the Maharashtra, India, with 54.2 % composed of vehicles that crashed into longitudinal barriers. Such accidents can be drastically reduced if more safe barriers are installed for traffic safety. A small Korean manufacturing company invented a new concept longitudinal barrier, the Rolling Barrier (RB), which has continuous pipes covered with urethane rings. This study aims to evaluate the effectiveness of the RB & to understand the RB’s characteristics of crash cushioning, how to correct the vehicle’s running direction & the required strength of barriers. Experiments with barriers performance & crashing vehicle behavior at curved sections using a 1.3-ton passenger car & a 3.5-ton truck showed satisfactory vehicle behavior as they ran parallel with the RB after crashing. The structural problem of the RB wasn’t found during the time of the crash. In the strength performance test using the 8-ton truck & in the passenger protection test using the 1.3-ton passenger car, the RB satisfied the Ministry of Construction & Transportation’s “ Guidelines for Installation & Management of Road Safety Facilities.” The differences between the RB & conventional barriers where crash cushioning & required strength of barriers were involved were verified by mathematical equations. The RB can be effectively used in curved road sections, ramps, medians & entrance/exit ramps in parking garages. Keywords: -accidents, longitudinal barrier, rolling barrier, traffic barrier, vehicle, collision

Investigation of speed and trajectory of motorcycle riders at curved road sections of two-lane rural roads under diverse lighting conditions

Introduction: Vehicular accidents at horizontal curves are over-represented compared to accidents that occur at tangent sections. Investigations have been conducted aimed at identifying the major causes that result in higher accident risk, both in terms of severity and rate, at curved road sections. Excessive or abrupt changes in speeding and improper vertical position are cited as major factors of lane departure, whereas other factors (either human or environmental) have also been documented. However, most research involves 4-wheel vehicles rather than other modes of transport that behave differently. More specifically, while motorcyclist fatalities occur more frequently than passenger vehicles, when accounting for vehicle distance traveled only a limited number of research studies address their behavior at curved road sections. Method: This paper presents the findings of field operational tests carried out by motorcyclists along two-lane rural roads with a wide range of horizontal curves using an instrumented motorcycle. Key objectives of the research included the conditions under which the motorcyclists differentiate their trajectory in regards to the direction of the horizontal curves, the correlation between the trajectory and the geometry of the road, and the impact of the lighting conditions on riders’ behavior. Results: The research showed that motorcyclists tend to ride closer to the centerline of the road, neglect the hazards associated with dim lighting conditions, and maintain constant speed in the left hand and the right-hand horizontal curves.

The Effect of Vehicle and Road Conditions on Rollover of Commercial Heavy Vehicles during Cornering: A Simulation Approach

Heavy vehicles make up a relatively small percentage of traffic volume on Malaysian roads compared to other vehicle types. However, heavy vehicles have been reported to be involved in 30,000–40,000 accidents yearly and caused significantly more fatalities. Rollover accidents may also incur cargo damages and cause environmental or human disasters for vehicles that carry hazardous cargos if these contents are spilled. Thus, in this paper, a comprehensive study was conducted to investigate the effects of vehicle and road conditions on rollover of commercial heavy vehicles during cornering at curved road sections. Vehicle conditions include the heavy vehicle class (based on the axle number and vehicle type), speed and gross vehicle weight, while road conditions include the cornering radius and coefficient of friction values. In order to reduce the risks involved in usage of actual heavy vehicles in crash experiments, a simulation approach using a multi-body vehicle dynamic software was applied in this study, where the verified virtual heavy vehicle model was simulated and the output results were extracted and analyzed. The results showed that a maximum of 40% and a minimum of 23% from the total number of simulations resulted in an unsafe condition (indicated as failed) during the simulations. From the unsafe conditions, two types of rollover accidents could be identified, which were un-tripped and tripped rollovers. The heavy vehicle speed was also found to have a strong correlation to the lateral acceleration (to cause a rollover), followed by gross vehicle weight, coefficient of friction and cornering radius, respectively.

Speed Models for Motorcycle Riders for Two-lane Rural Roads

The development of operating speed models has been the subject of numerous research studies in the past. Most of them present models that aim to predict free-flow speed in conjunction with the road geometry at the curved road sections considering various geometric parameters e.g., radius, length, preceding tangent, deflection angle. The developed models seldomly take into account the operating speed profiles of motorcycle riders and hence no significant efforts have been put so far to associate the geometric characteristics of a road segment with the speed behavior of motorcycle riders. The dominance of 4-wheel vehicles on the road network led the researchers to focus explicitly on the development of speed prediction models for passenger cars, vans, pickups, and trucks. However, although the motorcycle fleet represents only a small proportion of the total traffic volume motorcycle riders are over-represented in traffic accidents especially those that occur on horizontal curves. Since operating speed has been thoroughly documented as the most significant precipitating factor of vehicular accidents, the study of motorcycle rider's speed behavior approaching horizontal curves is of paramount importance. The subject of the present paper is the development of speed prediction models for motorcycle riders traveling on two-lane rural roads. The model was the result of the execution of field measurements under naturalistic conditions with the use of an instrumented motorcycle conducted by experienced motorcycle riders under different lighting conditions. The implemented methodology to determine the most efficient model evaluates a series of road geometry parameters through a comprehensive literature review excluding those with an insignificant impact to the magnitude of the operating speeds in order to establish simple and handy models.

Planning a Continuous Vehicle Trajectory for an Automated Lane Change Maneuver by Nonlinear Programming considering Car-Following Rule and Curved Roads

This study proposes a trajectory planning method for an automated lane change maneuver. We consider that the spatiotemporal trajectory of a controlled vehicle can be represented by a polynomial function and estimate the parameters of the polynomial function through nonlinear programming that does not rely on the assumed time horizon of lane change and the assumed final state of the controlled vehicle. When the controlled vehicle achieves its target lane, the state of this vehicle should be constrained by both the position and the speed of the forward vehicle. We integrate a car-following model into the nonlinear programming to constrain the state of the controlled vehicle at the end of the lane change. Notably, the interaction factors are taken into consideration: the motion of the vehicle that follows the controlled vehicle in the target lane can be influenced by the trajectory planning results of the controlled vehicle. The proposed trajectory planning method can simultaneously estimate the motion of the following vehicle and plan the trajectory for the controlled vehicle. Our proposed model can also work for curved road sections. We represent the curve information in the nonlinear programming by a regression model. We solve the nonlinear programming through the sequential quadratic program (SQP) algorithm and design a method to specify an initial guess for the algorithm. This paper finally demonstrates the effect of the proposed trajectory planning method under different scenarios.

Changes in Driver's Ability to Perceive Curved Road Sections Based on the Light-environment Conditions on Rural Roads at Night

Changes in Driver's Ability to Perceive Curved Road Sections Based on the Light-environment Conditions on Rural Roads at Night

Factors influencing noncompliance with bicycle passing distance laws

Many jurisdictions around the world have implemented laws to require a minimum distance when motor vehicles pass cyclists, but research into the factors influencing passing distances has produced inconsistent results, indicating the need for future research. This study examined the factors influencing motorists’ compliance with a legislated bicycle passing distance rule in Queensland, Australia. Unlike the earlier studies, which used volunteer riders to record passing events, this study used a naturalistic study design to record passing events where none of the motorists or the cyclists were aware of being studied. As a result, this study captured the ‘true’ driving and riding behaviours during passing events. The likelihood of non-compliance was greater on higher (70–80 km/h speed limits) and lower (40 km/h) speed roads than 60 km/h roads, at curved road sections, and on roads with narrower traffic lanes. Rider characteristics (age, gender, helmet status, type of clothing, type of bicycle, and individual or group riding) had no statistically significant association with compliance status. The findings indicate that efforts to improve cyclist safety during overtaking events should focus on non-rider related factors, such as roadway infrastructure characteristics.

A new methodology for approaching motorcycle riders’ behavior at curved road sections

The present paper focuses on the investigation of motorcycle riders’ behavior at curved road sections by introducing a new methodology based on global positioning system (GPS) technology. In the frame of the research, the determination of the optimum regression curve between the curve radius’ and the corresponding velocities, was investigated. Within the context of the paper field measurements were conducted, with the use of appropriate velocity recording equipment in order to confirm the efficiency of the proposed methodology. The measurements were conducted taking into account various factors that potentially influence riders’ behavior such as the different light conditions, the difference on riding experience level, the familiarity of the riders with the routes, the presence of pillion and the different road environments, such as width/condition of the road pavement, roadside land use, right/left hand curves etc. The experimental environment that served the needs of the experiment was mountain Pelion in Magnesia region in Greece and was based upon four primary conditions: the location, the type of the road, the weather conditions and finally, the time and date that the experiment would be conducted. The validation of the proposed methodology was performed by recruiting two motorcyclists. Their selection was based on demographic, psychometric and experience criteria. The research showed among others, that the regression curves could be used as a curve classification mean. Moreover, a significant variation was detected on the riders’ behavior when carrying a pillion related to their experience levels.

Performance of curved steel bridge railings subjected to truck collisions

Curved steel railings are used along curved road sections and bridges for safety. As with other railings, they are required to meet four performance standards as: (1) to prevent vehicles from leaving the road; (2) to protect occupants; (3) to guide vehicles back to the line of the road; and (4) to prevent penetration of the railing. Current Japanese specifications for railing design concern only straight railings. Some researchers and engineers suspect that curved railings are more dangerous than straight ones and this study finds that the impact angle between truck and railing, which affects both railing and truck behavior, can be larger than the angle allowed for in the Japanese specifications in some actual cases of curved roads and bridges. The purpose of this research is therefore to verify the above suspicion and to investigate the performances of curved railings subjected to collisions at the larger impact angles. A full-scale test would be the ideal methodology for this purpose but a test of the right sort would involve a considerable cost and effort. Thus numerical analyses are relied on to study the performance of curved steel railings according to the following procedures: (1) the railing and truck are represented by finite element models; (2) various cases are simulated of truck collisions with railings; and (3) numerical results are obtained for the consequent displacements, energy responses and truck behaviors as a means of evaluating the railing performances. The railings investigated in the various simulation cases are of grade SC and are either straight or have a curve radius of 100m, 150m, 280m or 460m. The software engine used for the numerical analysis is LS-DYNA 3D. Based on the results of the study, a design recommendation is proposed for curved railings.

Contribution to the Investigation of Motorcyclists’ Speed Prediction Equations for Two-Lane Rural Roads

The calculation of speed prediction equations has been the subject of numerous researches in the past. The majority of them present models to predict free-flow speed in terms of the road geometry at the curved road sections and more specifically in terms of the radiuses of the curves. Common characteristic is that none of them approaches the speed behavior of motorcycles since they are excluded from the datasets of the various studies. Instead, the models usually predict operating speed for other vehicle types such as passenger cars, vans, pickups and trucks. The present paper aims to cover this gap by developing speed prediction equations for motorcycles. For this purpose a new methodology is proposed while field measurements were carried out in order to obtain an adequate dataset of free-flow speeds along the curved sections of three different two lane rural roads. The aforementioned field measurements were conducted by two participants incorporating various road conditions (e.g. light conditions, experience level, familiarity with the routes). The ultimate target was the development of speed prediction equations by calculating the optimum regression curves between the curve radius’ and the corresponding velocities for the different road conditions. The research revealed that the proposed methodology could be used as a very useful tool to investigate motorcyclists’ behavior at curved road sections. Moreover it was feasible to draw conclusions correlating the speed adjustment with the various driving conditions.

Pavement Design for Curved Road Sections Fatigue Performance of Interfaces and Longitudinal Top-down Cracking in Multilayered Pavements

This paper focuses on damage processes other than the main one observed and studied in pavement design. Previous research has targeted the experimental fatigue performance of tack coats. The French Pavement Design method has been chosen herein to illustrate how interface fatigue performance can lead to improved design, especially when pavements are subjected to repeated horizontal loadings. In a curved pavement section, longitudinal top-down cracking is observed, and this damage process may also be taken into account during the design approach. A 3D finite element model has been derived to assess pavement lifetime. In conclusion, it is proposed to include the fatigue performance of interfaces when designing pavements with horizontal loadings and thin surface layers.

Pavement Design for Curved Road Sections

ABSTRACT This paper focuses on damage processes other than the main one observed and studied in pavement design. Previous research has targeted the experimental fatigue performance of tack coats. The French Pavement Design method has been chosen herein to illustrate how interface fatigue performance can lead to improved design, especially when pavements are subjected to repeated horizontal loadings. In a curved pavement section, longitudinal top-down cracking is observed, and this damage process may also be taken into account during the design approach. A 3D finite element model has been derived to assess pavement lifetime. In conclusion, it is proposed to include the fatigue performance of interfaces when designing pavements with horizontal loadings and thin surface layers.