Two-lane Roads Research Articles

A Promoted Design for Primary Coil in Roadway-Powered System

As technology advances, electric vehicle (EV) dynamic charging utilizing wireless power transfer (WPT) becomes prevalent. This new power supply mode allows running cars to be charged with electricity at any time on the road. Unlike traditional tramcars, the EVs can be free from rail limitation, and WPT technology provides maximal charging flexibility. This paper studies a WPT charging system, which uses a series of sectional primary coils. The relationship between primary coil size and transfer efficiency is fully explored. On the basis of sectional wireless power supply, the lateral movement of transfer coils is reported, and a promoted design for the primary coil that provides power for a two-lane road simultaneously is proposed.

보행자 작동신호기 설치기준 정립을 위한 적정 차량 및 보행자 교통량 추정모형

The main reason to install pedestrian pushbuttons is improving traffic operations. The current guideline for the installation of signal systems with pedestrian pushbuttons is car-oriented. It is difficult to clearly understand the guideline because there isn't an in-depth study to compare the pros and cons of the pedestrian- and vehicle-oriented methods in terms of waiting time. Thus, this study aims to estimate the waiting times of pedestrians and vehicles. The two delay times are compared considering the hypothetical circumstances such as geometry, pedestrian crossing time, pedestrian/vehicle counts and arrival distribution. The results show that when the pedestrian traffic volume exceeds 97 ped/h in the case of a two-lane road (one lane in each direction) the pushbutton system is effective and beneficial to pedestrians. It means that the total waiting time of pedestrians is less than the one of vehicles. Additional four scenarios are designed and tested by varying the number of lanes and design speeds. In conclusion, the pushbutton signal is more beneficial for pedestrians when the number of pedestrians is less than or equal to 85, 70, and 70 ped/h for the three-lane scenario, the four-lane with the design speed of 80km/h scenario, and the four-lane with the design speed of 100km/h, respectively. Keywords crosswalk; equilibrium; pedestrian push-button; pedestrian delay; standards for installation; vehicle delay ; 횡단보도; 적정 교통량; 보행자 작동신호기; 보행자 지체시간; 설치기준; 차량 지체시간 Language: ko

AN ALTERNATIVE METHOD OF ESTIMATING SPACE-MEAN SPEED

Average travelling speed usually applied in the traffic analysis as required in the fundamental traffic model. As one type of speed under the space-mean speed, most of the researchers have derived the equation to estimate the space-mean speed. There are a few factors that influence the speed changes along the segment. The fluctuate speed along the segment give an idea to average the spot mean speed from at least two points in order to estimate the space-mean speed. This paper explores an alternative method on how to convert the time-mean speed to space-mean speed that can represent the actual operating speed along segment using the average technique. A total of 18 data sets of time-mean speed and space-mean speed in six segments of uninterrupted two-lane single carriageway road were collected using automatic traffic counter and moving car observer, respectively. Two sets of automatic traffic counter were installed along the segment to record the spot speed and then converted to the time-mean speed, while the moving car observer were conducted concurrently to get the space-mean speed. The data sets were analysed using linear regression analysis. The results of summary of model show a strong relationship with coefficient of determination, R2=0.808, while ANOVA test results show the coefficient of constant and time-mean speed is not zero with p-value is less than 0.05 at confident level of 95%. The error obtained from this alternative equation are lesser than the established equation and it recommends that the alternative equation is acceptable.

Analysis of a novel two-lane lattice model on a gradient road with the consideration of relative current

In this paper, a novel hydrodynamic lattice model is proposed by considering of relative current for two-lane gradient road system. The stability condition is obtained by using linear stability theory and shown that the stability of traffic flow varies with three parameters, that is, the slope, the sensitivity of response to the relative current and the rate of lane changing. The stable region increases with the increasing of one of them when another two parameters are constant. By using nonlinear analysis, the Burgers, Korteweg–de Vries, and modified Korteweg–de Vries equations are derived to describe the phase transition of traffic flow. Their solutions present the density wave as the triangular shock wave, soliton wave, and kink–antikink wave in the stable, metastable, and unstable region, respectively, which can explain the phase transitions from free traffic to stop-and-go traffic, and finally to congested traffic. To verify the theoretical results, a series of numerical simulations are carried out. The numerical results are consistent with the analytical results. To check the novel model, calibration are taken based on the empirical traffic flow data. The theoretical results and numerical results show that the traffic flow on the gradient road becomes more stable and the traffic congestion can be efficiently suppressed by considering the relative current and lane changing, and the empirical analysis shows that the novel lattice model is reasonable.

Luminance-Corrected 3D Point Clouds for Road and Street Environments

A novel approach to evaluating night-time road and street environment lighting conditions through 3D point clouds is presented. The combination of luminance imaging and 3D point cloud acquired with a terrestrial laser scanner was used for analyzing 3D luminance on the road surface. A calculation of the luminance (cd/m2) was based on the RGB output values of a Nikon D800E digital still camera. The camera was calibrated with a reference luminance source. The relative orientation between the luminance images and intensity image of the 3D point cloud was solved in order to integrate the data sets into the same coordinate system. As a result, the 3D model of road environment luminance is illustrated and the ability to exploit the method for evaluating the luminance distribution on the road surface is presented. Furthermore, the limitations and future prospects of the methodology are addressed. The method provides promising results for studying road lighting conditions in future lighting optimizations. The paper presents the methodology and its experimental application on a road section which consists of five luminaires installed on one side of a two-lane road in Otaniemi, Espoo, Finland.

Portuguese two-lane highways: modelling crash frequencies for different temporal and spatial aggregation of crash data

The identification of contributory factors to crash frequencies observed in different highway facilities can aid transportation and traffic management agencies to improve road traffic safety. In spite of the strategic importance of the national Portuguese road network, there are no recent studies concerned with either the identification of contributory factors to road crashes or Crash Prediction Models (CPMs) for this type of roadway. This study presents an initial contribution to this problem by focusing on the national roads NR-14, NR-101 and NR-206, which are located in Northern region of Portugal. They are two-lane single carriageway rural roads. This study analysed the crash frequencies, Average Annual Daily Traffic (AADT) and geometric characteristics of 88 two-lane road segments. The selected segments were 200-m-long and did not cross through urbanized areas. The fixed length of 200 meters corresponds to the road length used in Portugal to define a critical point. Data regarding the annual crash frequency and the AADT were available from 1999 to 2010. Due to the high number of zero-crash records in the initial database, the data were explored to identify the best statistical modelling approach to be adopted. The Generalized Estimating Equations (GEE) procedure was applied to 10 distinctive databases formed by grouping the original data in time and space. The results show that the different observations within each road segment present an exchangeable correlation structure type. This paper also analyses the impact of the sample size on the model’s capability of identifying the contributing factors to crash frequencies. The major contributing factors identified for the two-lane highways studied were the traffic volume (expressed in AADT), lane width, vertical sinuosity, and Density of Access Points (DAP). Acceptable CPM was identified for the highways considered, which estimated the total number of crashes for 400-m-long segments for a cumulative period of two years.

Effects of safety measures on driver's speed behavior at pedestrian crossings

This paper reports the results of a multi-factorial experiment that was aimed at the following: (a) analyzing driver's speed behavior while approaching zebra crossings under different conditions of vehicle–pedestrian interaction and with respect to several safety measures and (b) comparing safety measures and identifying the most effective treatment for zebra crossings. Three safety countermeasures at pedestrian crossings (curb extensions, parking restrictions and advanced yield markings) and the condition of no treatment (baseline condition) were designed on a two-lane urban road and implemented in an advanced driving simulator. Several conditions of vehicle–pedestrian interaction (in terms of the time left for the vehicle to get to the zebra crossing at the moment the pedestrian starts the crossing) were also simulated. Forty-two drivers completed the driving in the simulator. Based on the recorded speed data, two analyses were performed.The first analysis, which focused on the mean speed profiles, revealed that the driver's speed behavior was affected by conditions of vehicle–pedestrian interaction and was fully consistent with previous findings in the literature and with the Threat Avoidance Model developed by Fuller.Further analysis was based on variables that were obtained from the speed profiles of drivers (the speed at the beginning of the deceleration phase, the distance from the zebra crossing where the deceleration began, the minimum speed value reached during the deceleration, the distance from the pedestrian crossing where the braking phase ended and the average deceleration rate). Multivariate variance analysis (MANOVA) revealed that there was a significant main effect for safety measures and for pedestrian conditions (the presence and absence of a pedestrian). The results identified that the curb extension was the countermeasure that induces the most appropriate driver's speed behavior while approaching the zebra crossing. This conclusion was also confirmed by outcomes of the questionnaire on the countermeasure's effectiveness. More than 80% of the drivers perceived that the curb extensions were effective, which indicates that when this countermeasure was present, the drivers were more willing to yield and that the visibility of the pedestrian crossing was better. For this countermeasure, the lowest number of interactions in which the drivers did not yield to a pedestrian was also recorded.

Evaluation of K 0 in stiff clay by back-analysis of convergence measurements from unsupported cylindrical cavity

The coefficient of earth pressure at rest K 0 of fine-grained soils is often being estimated empirically from the overconsolidation ratio (OCR). The relationships adopted in this estimation, however, assume that K 0 is caused by pure mechanical unloading and do not consider that a significant proportion of the apparent preconsolidation pressure may be caused by the effects of ageing, in particular by secondary compression. In this work, K 0 of Brno Tegel, which is a clay of stiff to hard consistency (apparent vertical preconsolidation pressure of 1800 kPa, apparent OCR of 7), was estimated based on back-analysis of convergence measurements from unsupported cylindrical cavity. The values were subsequently verified by analysing a supported exploratory adit and a two-lane road tunnel. As the simulation results are primarily influenced by soil anisotropy, it was quantified in an experimental programme. The ratio of shear moduli $$\alpha _G$$ was 1.45, the ratio of horizontal and vertical Young's moduli $$\alpha _E$$ was 1.67, and the value of Poisson ratio $$\nu _{tp}$$ was close to 0. The soil was described using a hypoplastic model considering very small strain stiffness anisotropy. For the given soil, the OCR-based estimation yielded $$K_0=1.3$$ , while Jaky formula estimated $$K_0=0.63$$ for the state of normal consolidation. The back-analysed value of K 0 was 0.75. The predicted tunnel displacements agreed well with the monitoring data, giving additional confidence into the selected modelling approach. It was concluded that OCR-based equations should not be used automatically for K 0 estimation. K 0 of many clays may actually be lower than often assumed.

Cellular automaton models for traffic flow considering opposite driving of an emergency vehicle

Aiming at two-lane road, this paper establishes three models to analyze the opposite-overtaking rules of emergency vehicle based on cellular automaton (CCA) model. Based on the simulation of mixed traffic flow for multi-density conditions, the density-speed diagrams have been obtained consequently. According to the analysis, when the traffic density of the opposite lane is low, the opposite driving behavior of emergency vehicle can improve the average speed effectively. At the same time, if the cocurrent lane is in high-density traffic, the traffic in the opposite lane will be disturbed, but the vehicles in the cocurrent lane will not be affected. The paper has further discussed the influence of different emergency vehicle driving behaviors on traffic. The results reveal that as the traffic of the opposite lane is in a low-density range, if emergency vehicle operates overtaking behavior precisely, the greater the density of the cocurrent lane is, the more obviously the speed improve. Meanwhile large random fluctuation of overtaking times will occur. While the risky lane change behavior displays different traffic characteristics, that is when the same direction lane is in high density, the speed increases slightly and the lane change number is changed regularly.

The tuning of human motor response to risk in a dynamic environment task.

The role of motor uncertainty in discrete or static space tasks, such as pointing tasks, has been investigated in many experiments. These studies have shown that humans hold an internal representation of intrinsic and extrinsic motor uncertainty and compensate for this variability when planning movement. The aim of this study was to investigate how humans respond to uncertainties during movement execution in a dynamic environment despite indeterminate knowledge of the outcome of actions. Additionally, the role of errors, or lack thereof, in predicting risk was examined. In the experiment, subjects completed a driving simulation game on a two-lane road. The road contained random curves so that subjects were forced to use sensory feedback to complete the task and could not rely only on motor planning. Risk was manipulated by using horizontal perturbations to create the illusion of driving on a bumpy road, thereby imposing motor uncertainty, and altering the cost function of the road. Results suggest continual responsiveness to cost and uncertainty in a dynamic task and provide evidence that subjects avoid risk even in the absence of errors. The results suggest that humans tune their statistical motor behavior based on cost, taking into account probabilities of possible outcomes in response to environmental uncertainty.

Estimación de longitud crítica en pendientes ascendentes en caminos bidireccionales

The critical length of grade on two-lane rural roads is used as criterion to assess the need of ascending lanes for heavy vehicles. To estimate it, a speed profile is needed, which depends on the road’s grade and length, and on the physical, dynamic and mechanical characteristics of heavy vehicles. The Chilean standard uses a speed profile for a design truck that have a weight-to-power ratio of 120 kg/kW and an entrance speed of 88 km/h. This unique model prevents from studying cases in which the entrance speed can be different or in which the design vehicle is significantly different to the design speed of standards due to local conditions and consequently, does not allow estimating realistic critical lengths of grades. In this work, speed profiles models based on acceleration and force equilibrium were simulated, considering weight-to-power ratios between 120 and 263 kg/kW, entrance speeds between 80 and 100 km/h. Several values of critical lengths of grades were estimated, which offers engineers more options when designing ascending slopes. Rev. ing. constr. [online]. 2015, vol.30, n.1, pp. 5-16. ISSN 0718-5073. http://dx.doi.org/10.4067/S0718-50732015000100001

Rumble strip sound level evaluation—Comparison of three designs

Results of sound level monitoring from three types of longitudinal rumble strips installed along the edge of two-lane rural roads are discussed. This study was in response to objections by landowners about unwanted noise caused by vehicles traveling over rumble strips. The ultimate study goal is to provide maximum tactile and tonal sound levels at the driver position while minimizing exterior sound levels. Both exterior and vehicle interior sound levels were measured for three longitudinal edge-of-pavement rumble strip designs—California, Pennsylvania, and Minnesota. Simultaneous digital audio files were also recorded. Three vehicles types were tested at 30, 45, and 60 mph. Comparison of exterior levels and interior sound levels showed that the Pennsylvania design is the quietest, both interior and exterior. Interior levels from the Minnesota and California designs are similar but exterior levels are higher for the Minnesota design. The California design generates two tonal peaks. The Minnesota design generates only one higher tonal peak. Studies to date have not accurately addressed the distance at which a rumble strip signal can be heard. Sound levels were projected perpendicular to the roadway suggesting detectability at over a mile from the Minnesota design in a typical rural environment.

Investigation of pedestrian crashes on two-way two-lane rural roads in Ethiopia

Understanding pedestrian crash causes and contributing factors in developing countries is critically important as they account for about 55% of all traffic crashes. Not surprisingly, considerable attention in the literature has been paid to road traffic crash prediction models and methodologies in developing countries of late. Despite this interest, there are significant challenges confronting safety managers in developing countries. For example, in spite of the prominence of pedestrian crashes occurring on two-way two-lane rural roads, it has proven difficult to develop pedestrian crash prediction models due to a lack of both traffic and pedestrian exposure data. This general lack of available data has further hampered identification of pedestrian crash causes and subsequent estimation of pedestrian safety performance functions. The challenges are similar across developing nations, where little is known about the relationship between pedestrian crashes, traffic flow, and road environment variables on rural two-way roads, and where unique predictor variables may be needed to capture the unique crash risk circumstances. This paper describes pedestrian crash safety performance functions for two-way two-lane rural roads in Ethiopia as a function of traffic flow, pedestrian flows, and road geometry characteristics. In particular, random parameter negative binomial model was used to investigate pedestrian crashes. The models and their interpretations make important contributions to road crash analysis and prevention in developing countries. They also assist in the identification of the contributing factors to pedestrian crashes, with the intent to identify potential design and operational improvements.

Coordination of horizontal and sag vertical curves on two-lane rural roads: Driving simulator study

The highway geometric design guidelines for several countries provide suggestions for the coordination of horizontal curves overlapping with sag vertical curves (sag combinations) to avoid combined configurations that produce undesirable optical effects and reduced safety. Such suggestions are derived from studies based on the drawing of the perspective of the road. This drawing method is severely limited with respect to the simulation of the perspective view of the highway to the driver during the dynamic task of driving. Interactive driving simulation methods are deemed to be more efficient for these objectives.This paper reports the results of a study carried out using an interactive driving simulator to evaluate the effects on the driver's speed behavior of different configurations of sag combinations and non-combined curves on a flat grade with the same features as the horizontal curves of the sag combinations (reference curves). The speed behaviors of drivers along the tangent–curve transitions of sag combinations and reference curves were recorded. The speed on the approach tangent, the speed at the midpoint of the horizontal curve and the maximum speed reduction (MSR), the difference between the maximum speed on the last 200m of the approach tangent and the minimum speed on the first half of the horizontal curve, were analyzed. One-way repeated MANOVA was performed to determine if the driver's speed behavior on the horizontal curves was influenced by different configurations of sag combinations and reference curves.The primary result was that on suggested sag combinations, the driver's speed behavior did not differ in any statistically significant way from that on the reference curves. Whereas the critical sag combinations (configurations that should be avoided) caused high values of maximum speed reduction along the tangent–curve transition, which pointed to the driver's reaction to an incorrect perception of the road alignment. Therefore, this result confirmed the effectiveness of the road design guidelines for the coordination of horizontal curves and sag vertical curves.

Impact of Vehicles on Smoke Spread Dynamics in the Case of Fire in Road Tunnel

In this paper, the impact of vehicles in road tunnel on smoke spread in case of fire is illustrated using the FDS (Fire Dynamics Simulator) system. FDS is a CFD-based fire field model capable to simulate fire in various environments capturing a big variety of physical processes related to fire. A set of simulations of fire in a 300 m long two-lane single directional road tunnel with longitudinal ventilation is described focusing on the impact of vehicles on the smoke spread dynamics in the tunnel.

On-road experiment to assess drivers’ detection of roadside targets as a function of headlight system, target placement, and target reflectance

Adaptive headlights swivel with steering input to keep the beams on the roadway as drivers negotiate curves. To assess the effects of this feature on driver’s visual performance, a field experiment was conducted at night on a rural, unlit, and unlined two-lane road during which 20 adult participant drivers searched a set of 60 targets. High- (n=30) and low- (n=30) reflectance targets were evenly distributed on straight road sections and on the inside or outside of curves. Participants completed three target detection trials: once with adaptive high-intensity discharge (HID) headlights, once with fixed HID headlights, and once with fixed halogen headlights. Results indicated the adaptive HID headlights helped drivers detect targets that were most difficult to see (low reflectance) at the points in curves found by other researchers to be most crucial for successful navigation (inside apex). For targets placed on straight stretches of road or on the outside of curves, the adaptive feature provided no significant improvement in target detection. However, the pattern of results indicate that HID lamps whether fixed or adaptive improved target detection somewhat, suggesting that part of the real world crash reduction measured for this adaptive system (Highway Loss Data Institute (HLDI), 2012a) may be due to the differences in the light source (HID vs. halogen). Depending on the scenario, the estimated benefits to driver response time associated with the tested adaptive (swiveling HID) headlights ranged from 200 to 380ms compared with the fixed headlight systems tested.

Empirical Bayes Before–After Study on Safety Effect of Narrow Pavement Widening Projects in Texas

Texas has approximately 40,000 lane miles (64,000 lane kilometers) of two-lane farm-to-market (FM) and ranch-to-market (RM) roads with total paved widths of 18 to 22 ft (5.5 to 6.7 m), most of which are in rural areas. Narrow pavement widening in Texas typically involves adding lane width, a narrow shoulder, or both to increase the travel way in each direction of a narrow FM and RM road by 1 to 9 ft (0.3 to 2.7 m). The main reasons for roadway widening are usually to do any or all of the following: improve safety, increase structural capacity, and enhance pavement performance. The goal of this study was to investigate the safety effects of narrow pavement widening projects for rural two-lane FM and RM roads in Texas. A before–after comparison study was conducted with the empirical Bayes method to evaluate how wider lanes and shoulders affect crash occurrence, by type and severity. Of the 22 studied projects, analysis showed a 31.5% reduction in total crashes, a 35.7% reduction in run-off-the-road crashes, and a 55.4% reduction in head-on crashes after narrow widening projects were carried out. The projects were also effective in reducing fatal crashes and injuries by about 29.5%. These findings suggest that pavement widening is an effective safety countermeasure on narrow two-lane FM and RM roads in rural areas.

Does Roadside Vegetation Affect Driving Performance?: Driving Simulator Study on the Effects of Trees on Drivers' Speed and Lateral Position

This study investigated the effects of roadside vegetation on driving performance on a two-lane rural road. In a driving simulation, 44 participants drove along seven roadside tree configurations. The configurations were characterized by two offsets of trees from the road edge (1.5 and 4.0 m) and three spacings between trees (10.0, 17.5, and 25.0 m) located on the roadside of a two-lane rural road that was 6.0 m wide. One additional configuration, without trees, was used as the baseline condition. The investigation was developed over five geometric elements: sharp left curve, sharp right curve, gentle left curve, gentle right curve, and tangent. Compared with the baseline condition, when trees were close to the road edge, drivers were found to decrease their speed significantly and move toward the centerline of the road. By contrast, when the offset of trees was increased, drivers adopted higher speeds that increased the distance from the road edge but with a lower left lateral displacement. This occurred along all five geometries, especially on sharp curves. Tree spacing did not affect the drivers' speed but significantly influenced the lateral position: drivers moved farther away from the road edge when tree spacing was decreased. The results demonstrated that drivers balanced the useful guidance information that roadside trees provided with the risk associated with the presence of trees: when trees were far away, the sense of guidance was predominant, and drivers adopted higher speeds; when trees were closer, drivers saw the trees as a risk, slowed down, and moved further away from them. Such driving behavior has direct impacts on the safety implications of roadside trees.

An Experimental Study on Lateral Acceleration of Cars in Different Environments in Sichuan, Southwest China

In view of the tremendous improvements in the dynamic performance of automobiles and changes in the composition of drivers over the past several decades, it is valuable to examine the distribution of automobile’s lateral acceleration in new environments. The lateral accelerations, speeds, and trajectory curvatures of a passenger car on twelve highways with different design speeds and topographies were obtained. By synchronizing, matching, and counting, the distribution of the lateral acceleration was obtained, and the level of driving comfort was estimated. The10th,15th,50th,85th, and90thpercentile values of the lateral acceleration on three road types (six-lane road, four-lane road, and two-lane road) were found. Combined with scatter diagrams of the lateral acceleration over the curvature, the negative correlation between the lateral acceleration and the curvature was analyzed and interpreted. In addition, regression models of the lateral acceleration with the curvature for the three kinds of roads were established. Based on scatter diagrams of the lateral acceleration over the speed, regression models of the averageaydepending on the speed and the85thpercentileaydepending on the speed of passenger cars and buses were established. The research provides calculation parameters and a control basis for operating speed prediction, pavement material design, and maximum and minimum limit value determination for the superelevation ratios and curve radii.

Development and Effective Use of a Wire Rope Guardrail System for Two-lane Roads in Japan

Fatal high-speed head-on collisions often occur in the limited spaces of two-lane roads without median strips. Wire rope guardrail systems can be seen as an alternative to median strips. Such systems use thin posts, have a buffering function and require minimal width. The purpose of this study was to develop a wire rope guardrail system with a buffering function as a separator for two-lane roads. CG simulation and collision experiments using real vehicles were conducted to determine the necessary characteristics of the fence, and performance tests were conducted in accordance with guard fence installation criteria. As a result, a wire rope guardrail system that satisfies Japan's Am Performance Standard Criteria for expressway median strips was developed. A driving test was conducted to study the feasibility of introduction to two-lane expressways.