Journal articles on the topic 'Curve radius'
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Wang, Pu, Daolin Si, Shuguo Wang, and Qiang Yi. "Study on Gage Widening Methods for Small-Radius Curves." Applied Sciences 11, no. 12 (June 8, 2021): 5334. http://dx.doi.org/10.3390/app11125334.
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Existing gage widening standards and the influence of gage widening on the curve passing performance of trains and rail wear were examined. The existing gage widening theory can determine the minimum curve radius that needs to be widened, the widening value required by curves with different radii, and whether multiaxle locomotives can pass small-radius curves. However, it does not quantify the influence of the gage widening value on the curve passing performance and track maintenance workload. The range of the minimum curve radius that needs to be widened is 220–350 m, whereas some countries adopt a radius of 600 m; the maximum gage widening range is 15–20 mm, and few countries adopt gage widening values exceeding 30 mm. When the gage widening value increases from 0 to 10 mm, the lateral force of the curved wheel or rail with a radius less than 300 m is reduced by 16–20%, and that with a radius exceeding 300 m is reduced by 10–15%. The results of this study reveal that using proper gage widening values can reduce the lateral force of the wheel or rail and improve the curve passing performance. In the rail lifecycle, the implementation of the current gage widening standard requires only one gage adjustment operation, whereas the implementation of the original gage widening standard requires doubling gage adjustment operations.
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Jose Andueza, Pedro. "Mathematical Models of Vehicular Speed on Mountain Roads." Transportation Research Record: Journal of the Transportation Research Board 1701, no. 1 (January 2000): 104–10. http://dx.doi.org/10.3141/1701-13.
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Mathematical models were developed to estimate vehicular speed on curves and tangents in mountain roads. The 85th percentile speed for curves was estimated by using the radius of the curve under consideration, the radius of the previous curve, sight distance in the curve, and tangent length before the curve. The average speed was calculated by using the radius of the curve under consideration, the radius of the previous curve, and sight distance. The 85th percentile and the average speed were estimated by using the radius of the previous curve and tangent length. Speeds adopted by drivers respond not to engineer’s design speed but to geometric characteristics of the road. A design procedure is proposed that takes advantage of available design speed and driver behavior on the road at the same time. On a curve, drivers consider two efficiency measures: speed and comfort. On some curves, they prefer to feel a certain degree of discomfort in exchange for obtaining greater speeds. For some geometric conditions, drivers adopt a speed that sacrifices not only comfort but also safety.
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Loktev, Alexey Alexeevich, Vadim Vadimovich Korolev, Irina Viktorovna Shishkina, and Vladislav Sergeevich Kuskov. "Selection of shape for turnout curve of high-speed switches." Transport of the Urals, no. 3 (2020): 62–67. http://dx.doi.org/10.20291/1815-9400-2020-3-62-67.
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The main factor at determination of radius of turnout curve under the conditions of comfortable driving is the limitation of centrifugal acceleration increment amount per unit time. For this reason, at designing high-speed switches it is advisable to use variable-radius curves as a turnout curve. The paper considers variable-radius curves - cubic parabola, parabola of the fourth order and sine curve. On the basis of the comparative assessment it is established that the sine curve is the most acceptable variant for using as a turnout curve in high-speed switches.
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Lou, Ping, Yonghe Li, Hongbo Xiao, Zhengang Zhang, and Shide Lu. "Influence of Small Radius Curve Shield Tunneling on Settlement of Ground Surface and Mechanical Properties of Surrounding Rock and Segment." Applied Sciences 12, no. 18 (September 11, 2022): 9119. http://dx.doi.org/10.3390/app12189119.
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Compared with straight tunnels, over-excavation occurs on the inner side of the curved section during shield construction of small radius curved tunnels, and the disturbance to the ground surface and mechanical properties of surrounding rock and segment are more severe. This paper establishes the numerical models of small radius curve tunnels and straight tunnels to study the characteristics of surface deformation caused by the shield excavation of small radius curved tunnels and the influence of shield construction parameters on ground settlement, surrounding rock deformation, and segment force. The maximum error between the numerical simulation results and the measured surface settlement curve is 7.3%, which is in good agreement. The results show that: (1) The maximum value of the surface settlement of the small radius curve tunnel appears inside the curve section, and with the decrease in the curve radius, the surface settlement increases, and the distance between the peak settlement point and the tunnel center is larger. (2) When the curve radius of the tunnel is smaller, the lateral displacement of the ground surface moves farther to the inner side, and the range of soil mass with lateral displacement in the inner side is also wider. (3) Increasing the heading face pressure and grouting pressure can reduce surface settlement, but the heading face pressure should not exceed 350 kPa, and the grouting pressure should not exceed 250 kPa. (4) When the curve radius is smaller, the deformation of surrounding rock and the segment stress is larger.
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He, Jiao Long, Shu Guang Chen, and Xin Sheng Zhang. "Research on Technology of Highway Curve and Slope Road Segment Alignment Safety Design." Applied Mechanics and Materials 204-208 (October 2012): 1665–68. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.1665.
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In the paper, Combination curved with slope road segment on the driving experiment , The paper is analyzed the curve and slope road segment on Gradient, Horizontal Curve Radius, Speed and heart rate these variables of the inherent relation and law. The model of the relationship of the longitudinal slope and horizontal curve radius and heart rate is set up. By employing regression analysis, Conduct quantitative analysis, calculation and can be determined by the minimum horizontal curve radius value of vertical slope corresponding to at different vehicle-speeds on curved with longitudinal slope,Theoretical reference is provided for designers in the design technology research.
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Xin, Chunfu, Zhenyu Wang, Pei-Sung Lin, Chanyoung Lee, and Rui Guo. "Safety Effects of Horizontal Curve Design on Motorcycle Crash Frequency on Rural, Two-Lane, Undivided Highways in Florida." Transportation Research Record: Journal of the Transportation Research Board 2637, no. 1 (January 2017): 1–8. http://dx.doi.org/10.3141/2637-01.
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The association between horizontal curve design (e.g., radius and type) on rural, two-lane, undivided highways and motorcycle crash frequency is not well documented in existing reports and publications. This study aimed to investigate the effects of design parameters and associated factors on the occurrence of motorcycle crashes with consideration of the issue of unobserved heterogeneity. A random-parameters negative binomial regression model was developed on the basis of data on 431 motorcycle crashes, which were collected on 2,179 horizontal curves along two-lane, undivided highways in Florida for 11 years (2005 to 2015). Four normally distributed random parameters (i.e., logarithm of curve radius, reverse curves, pavement condition, and rough pavement indicator) were identified to represent their heterogeneity caused by unobserved factors over time, space, individuals, or some combination thereof. The major conclusions are the following: ( a) an increase in curve radius, on average, significantly and near-logarithmically reduced motorcycle crash frequency on rural, two-lane, undivided highways (this effect was more significant when the curve radius was less than 2,000 ft); ( b) 74.8% of reverse curves tended to reduce motorcycle crash frequency on rural, two-lane, undivided highways (for the remaining 25.2%, the effect had an opposite effect; on average, the likelihood of motorcycle crashes on reverse curves decreased by 39%); ( c) the crash modification function (CMF) for curve radius on rural, two-lane, undivided highways was established, given the radius of 5,000 ft as the baseline, as a power formula, CMF = (radius/5,000)-0.208.
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Hasan, Nazmul. "Threshold Radius of a Ballasted CWR Curved Track: Curve Classification." Journal of Transportation Engineering, Part A: Systems 143, no. 7 (July 2017): 04017026. http://dx.doi.org/10.1061/jtepbs.0000054.
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Mauriello, Filomena, Alfonso Montella, Mariano Pernetti, and Francesco Galante. "An Exploratory Analysis of Curve Trajectories on Two-Lane Rural Highways." Sustainability 10, no. 11 (November 17, 2018): 4248. http://dx.doi.org/10.3390/su10114248.
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This paper is aimed at obtaining a better understanding of driving behavior on horizontal curves of two-lane rural highways in terms of trajectories in relation to the different curve radii and directions by a driving simulator experiment. The driving simulator experiment involved 50 drivers and eight classes of curve radii, ranging from 125 m to 800 m. Overall, 2000 curve trajectories were analyzed and classified. Six major classes were defined: (1) ideal behavior, (2) normal behavior, (3) driving close to the centerline, (4) driving outside in curve approach, (5) cutting, and (6) correcting. Furthermore, 21 sub-classes were introduced to consider both lane departures and location of the corrective actions. The CATANOVA tests and Bhapkar’s tests showed that both the curve radius and the curve direction had a significant effect on the classification results. To get a clearer understanding of the effect of the curve radius and direction on curve negotiation, three macro-classes corresponding to safe, intermediate, and dangerous behavior were introduced. The safest behaviors significantly increased with the curve radius while the most dangerous behaviors significantly decreased with the curve radius. Furthermore, left curves showed a higher proportion of dangerous trajectories. Overall, it seems that the driving trajectories are a promising surrogate measure of safety as highlighted by the correlation between the trajectories identified as dangerous and the radii of the curves.
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Himes, Scott, Richard J. Porter, Ian Hamilton, and Eric Donnell. "Safety Evaluation of Geometric Design Criteria: Horizontal Curve Radius and Side Friction Demand on Rural, Two-Lane Highways." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 3 (March 2019): 516–25. http://dx.doi.org/10.1177/0361198119835514.
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AASHTO’s A Policy on Geometric Design of Highways and Streets, 6th Edition, provides design criteria for horizontal curve elements based on the point-mass model. The model equates the centripetal force needed to navigate a horizontal curve of a specific radius traveling at the design speed to the combination of superelevation rate and side friction needed to achieve that force. Few researchers have examined the safety impacts of horizontal curve radius, superelevation rate, and design speed through crash-based research. None of the research reviewed included the effects of design speed or superelevation rate in the crash modification factors (CMFs) or functions. This research explored these factors using a negative binomial regression modeling approach based on data collected from the SHRP 2 RID 2.0 for 889 horizontal curves on rural two-lane highways in Indiana and Pennsylvania, which resulted in roadway departure crash modification functions for horizontal curve radius and side friction demand. The crash modification function for side friction demand includes an interactive component of horizontal curve radius and speed and a direct effect of superelevation rate on roadway departure crashes. The results showed that roadway departure crashes are expected to increase for decreasing curve radius, increasing posted speed limit, and decreased superelevation rate. Furthermore, curve-related CMFs were sensitive to the curve radii used in their development. CMFs developed from curves with larger radii tended to result in larger CMFs. Sample applications are provided for computing the effects of changing the horizontal curve radius, posted speed limit, or both on proposed alternatives.
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Chen, J. T., J. W. Lee, S. K. Kao, and Y. T. Chou. "Construction of a curve by using the state equation of Frenet formula." Journal of Mechanics 37 (2021): 454–65. http://dx.doi.org/10.1093/jom/ufab014.
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Abstract In this paper, the available formulae for the curvature of plane curve are reviewed not only for the time-like but also for the space-like parameter curve. Two ways to describe the curve are proposed. One is the straight way to obtain the Frenet formula according to the given curve of parameter form. The other is that we can construct the curve by solving the state equation of Frenet formula subject to the initial position, the initial tangent, normal and binormal vectors, and the given radius of curvature and torsion constant. The remainder theorem of the matrix and the Cayley–Hamilton theorem are both employed to solve the Frenet equation. We review the available formulae of the radius of curvature and examine their equivalence. Through the Frenet formula, the relation among different expressions for the radius of curvature formulae can be linked. Therefore, we can integrate the formulae in the engineering mathematics, calculus, mechanics of materials and dynamics. Besides, biproduct of two new and simpler formulae and the available four formulae in the textbook of the radius of curvature yield the same radius of curvature for the plane curve. Linkage of centrifugal force and radius of curvature is also addressed. A demonstrative example of the cycloid is given. Finally, we use the two new formulae to obtain the radius of curvature for four curves, namely a circle. The equivalence is also proved. Animation for 2D and 3D curves is also provided by using the Mathematica software to demonstrate the validity of the present approach.
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Purwanto, Djoko, Amelia Kusuma Indriastuti, and Kami Hari Basuki. "Hubungan antara Kecepatan dan Kondisi Geometrik Jalan yang Berpotensi Menyebabkan Kecelakaan Lalu Lintas pada Tikungan." MEDIA KOMUNIKASI TEKNIK SIPIL 21, no. 2 (June 8, 2016): 83. http://dx.doi.org/10.14710/mkts.v21i2.11234.
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To date, the traffic accident number on hairpin curve is still quite high. This is exacerbated by speeding driving behaviour of some road users.This research aims to identify the factors that cause traffic accidents and drivers’ behaviour at the curve; to review curve geometric design; and to develop a relationship among speed, curve geometric condition and the accident at the curve. This study simply reviewed three hairpin curves that were prone to be blackspots in Batang. The dominant factors that cause accidents were human error and road condition. The driver’s speeding behaviour was indicated by the speed that was lessen when entering and increase when leaving the curve. There were speed variations among vehicles in research location that could increase the number of accident. The results of the geometric review showed that the radius of all curves evaluated did not meet the standard, i.e. less than the minimum radius. Another result of this study was relationships among speed, geometric condition and accident number, as shown by the following formula: Speed = 0.095 Radius + 42.889, No. of accident = - 0.785 Radius + 0.008 Speed - 284.301, and EAN = 0.028 Speed - 1108.689.
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Montella, Alfonso, Francesco Galante, Filomena Mauriello, and Massimo Aria. "Continuous Speed Profiles to Investigate Drivers' Behavior on Two-Lane Rural Highways." Transportation Research Record: Journal of the Transportation Research Board 2521, no. 1 (January 2015): 3–11. http://dx.doi.org/10.3141/2521-01.
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To improve highway design consistency, several studies developed operating speed prediction models and investigated drivers' speed behavior. Most existing models are based on spot speed data that assume constant operating speed throughout the horizontal curves and occurrence of acceleration and deceleration only on tangents. To overcome limitations associated with existing models, this study investigated continuous speed profiles with an experiment that used a high-fidelity dynamic-driving simulator on a two-lane highway. A piecewise linear regression model and locally weighted regression scatter-plot smoothing were used to remove noise in the data set while preserving underlying patterns and to identify significant changes in the speed profile. Based on the smoothed speed profiles, models to predict operating speed in curves and in tangents, deceleration and acceleration rates to be used in the operating speed profiles, and starting and ending points of constant operating speed in curve were developed. Radius of the curve notably affected not only the operating speed in the curve but also the operating speed of the tangent following the curve: the smaller the radius, the lower the operating speed of the exit tangent. Both acceleration and deceleration rates increased with curvature. This study found that operating speed was not constant along curves. On small radius curves, deceleration ended close to the center of the curve, and acceleration starts, close to the end of the curve. Increasing the curve radius, the end point of deceleration moves toward the curve's beginning, whereas the start of acceleration moves toward the center of the curve.
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Sharf Aldeen, Asame, Ali Abdi Kordani, Afshin Fallah, and Seyed Mohsen Hosseinian. "Safety Comparison of Simple and Spiral Horizontal Curves Based on Side Friction Factor Dynamic Modeling." Journal of Advanced Transportation 2023 (February 10, 2023): 1–23. http://dx.doi.org/10.1155/2023/7954346.
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A horizontal curve’s geometric design is considered an important factor in highway accidents, and simple and spiral curves are regarded as the most common types of horizontal curves. Various factors affect the safety of horizontal curves, one of the most important of which is the side friction factor in the horizontal curves. Therefore, in this study, the safety of simple and spiral horizontal curves was investigated for the E-class sedan, E-class SUV, and two-axle conventional truck based on the side friction factor. In this regard, CarSim and TruckSim vehicle dynamic simulation software were utilized using 360 scenarios, including vehicle speed, vehicle type, curve radius, and road geometry. It was revealed that the maximum side friction factor for all vehicles in the simple horizontal curve was higher than the spiral horizontal curve. Also, the process of increasing the side friction factor was carried out with a gentler slope in the spiral horizontal curve. Except for the radius of 0.7 times the maximum radius of the spiral horizontal curve (R) for the truck and the radii of 0.7 R and 0.9 R for the sedan and SUV, the maximum side friction factor in simple and spiral horizontal curves was lower than the AASHTO recommended values, which shows that the spiral horizontal curve was better and safer compared to the simple horizontal curve based on the side friction factor.
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Maljković, Biljana, and Dražen Cvitanić. "Evaluation of design consistency on horizontal curves for two-lane state roads in terms of vehicle path radius and speed." Baltic Journal of Road and Bridge Engineering 11, no. 2 (June 27, 2016): 127–35. http://dx.doi.org/10.3846/bjrbe.2016.15.
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Experimental investigation was conducted on a 24 km long segment of the two-lane state road to collect the driver behavior data. The research involved 20 drivers driving their own cars equipped with the GPS device. Considering the impact of path radius and speed on the side friction demand, the design consistency on horizontal curves was evaluated by determining the margins of safety. The analysis showed that the vehicle path radii were mainly smaller than curve radius, on average for 12%. Regression analysis indicated that the percentage difference between the curve radius and vehicle path radius is not affected by the speed, speed differential and geometric characteristics of the curve and surrounding elements. Two different margins of safety were analyzed. One is the difference between maximum permissible side friction (based on design speed) and side friction demand, while another is the difference between side friction supply (based on operating speed) and side friction demand. Generally, demands exceeded supply side friction factors on curves with radii smaller than 150 m, whereas “poor” conditions (in terms of Lamm’s consistency levels) were noted for curves under approximately 220 m. Both values are very close to the critical radius below which higher accident rates were observed according to several accident studies. Based on the results of the research, it is proposed to use a 12% smaller curve radius for the evaluation of margin of safety and that curves with radii smaller than 200 m should be avoided on two-lane state roads outside the built-up area.
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Popović, Zdenka, Luka Lazerević, and Nikolay Vatin. "Analysis of Track Gauge Widening in Curves with Small Radius." Applied Mechanics and Materials 725-726 (January 2015): 967–73. http://dx.doi.org/10.4028/www.scientific.net/amm.725-726.967.
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In this paper it was performed curve negotiation analysis of three axle bogie of locomotive type JŽ 461. This locomotive has large distance between first and middle i.e. middle and last axle, which leads to increased lateral forces during curve negotiation. Final result might be widening of track gauge in curves with small radius. This paper points that Infrastructure Manager must take into account vehicle performances and type of track when defines track gauge in curves.
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You, Run Wei. "Safety Design on Small Radius Curve of Mountain Road." Applied Mechanics and Materials 587-589 (July 2014): 981–84. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.981.
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Bend of small radius curve is accident-prone locations. Taking small radius curve as research object, by researching on traveling track and design of widening small radius curve, super elevation, center line as well as security problems of traffic facilities, puts forward measures on safety design on small radius curve of mountain road.
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Zheng, Xue Lian, Xian Sheng Li, Cheng Wu Jiao, Gang Bai, and Yuan Yuan Ren. "Study on Road Geometric Alignment Parameters Based on Vehicle Handling Stability Simulation." Applied Mechanics and Materials 404 (September 2013): 273–79. http://dx.doi.org/10.4028/www.scientific.net/amm.404.273.
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Unreasonable road geometric alignment has a negative influence on vehicle handling stability, especially when vehicle drives with a high speed. For horizontal road alignment, radius and banking of circular curve are the most popular and important parameters. To investigate the influence of horizontal road alignment on vehicle handling stability, a 3 degrees-of-freedom vehicle dynamic model is established. Three road horizontal curves with different radius are established in Carsim environment to investigate the influence of curve radius on vehicle handling stability and four different banking curve roads are built to study the impact of road banking on vehicle roll stability. The research achievement will provide theoretical basis and technical support for road geometric alignment design.
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Wang, Zhiqiang, and Zhenyu Lei. "Formation Mechanism of Metro Rail Corrugation Based on Wheel–Rail Stick–Slip Behaviors." Applied Sciences 11, no. 17 (September 1, 2021): 8128. http://dx.doi.org/10.3390/app11178128.
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Field investigation shows that most corrugations occur on the inner rail surface of curved tracks with a radius of less than 700 m. In order to explore the formation mechanism of metro corrugation, the relationship between wheel–rail stick–slip characteristics and rail corrugation is studied by combining single wheelset curving and a rigid–flexible coupling model. The numerical results illustrate that the lateral torsional stick–slip vibration of inner rail–inner wheel of the guiding wheelset on the small radius curve eventually leads to the generation of inner rail corrugation, and the lateral torsional stick–slip vibration of outer rail–outer wheel of the driven wheelset may also occur, but the intensity is weak and the probability is low. The lateral torsional stick–slip vibration of inner rail–inner wheel of the guiding wheelset on the large radius curve is also easy to cause inner rail corrugation, but the degree of inner rail corrugation is lower than that on the small radius curve; the outer rail on the large radius curve is still not easy to produce corrugation. The formation mechanism of rail corrugation on the straight track is different from that on the curve track, which is mainly related to the wheel–rail longitudinal torsional stick–slip vibration.
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Felipe, Emmanuel, and Francis Navin. "Automobiles on Horizontal Curves: Experiments and Observations." Transportation Research Record: Journal of the Transportation Research Board 1628, no. 1 (January 1998): 50–56. http://dx.doi.org/10.3141/1628-07.
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Statistical information on the basic variables involved in driving through a horizontal curve was obtained using a 4×4 Latin square design experiment to measure the action of automobile drivers in test track horizontal curves. The independent variables used in the test curves were speed (comfortable, fast); pavement surface (dry, wet); driver (male, female); and curve radius (16 m, 26 m, 60 m, 100 m). The measured output was the driver’s selected speed and corresponding lateral acceleration. In addition, the passengers indicated their comfort level on a four-point semantic scale. Expert drivers also drove the test curves to establish the upper limits of the driver-vehicle-tire system. Field observations of four curves along a two-lane rural mountain highway measured driver vehicle speed, lateral acceleration, and lateral position. The results indicate that, for a comfortable ride, drivers are limited by their comfortable lateral acceleration on small radius curves and seek the “environmental speed” on large radius curves.
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Wang, Cai Yun, Peng Shen, Wen Zhong, and Qi Yue Liu. "Numerical and Experiment Analysis of Rail Wear." Advanced Materials Research 189-193 (February 2011): 697–702. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.697.
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The rolling contact wear is a severe problem and meets with much widespread interest in the world. This paper describes an numerical method and simulation experiment investigation on the rail wear affected by the curve radius and axle load etc. The creep force ,stick/slip areas of contact particles, and friction work of wheel/rail in static condition are analyzed by kalker’s program CONTACT. The effect of curve radius and axle load on rolling wear behaviour of rail is investigated by simulation experiment. The results of numerical and experiment indicates that with the decreasing of curve radius and the increasing of axle load, the wear value of rail increase nonlinearly, especially in the condition of the curve radius is less than 1200m,the wear value of rail increase rapidly. And with the decrease of curve radius, the maximum slippage decrease gradually, and the stick areas decrease while the slip areas increase. The growth speed of friction work of wheel/rail in the condition of smaller curve radius and heavier axle load is faster than in the condition of larger curve radius (straigth line) and lighter axle load.
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Hasan, Moudud, Tarek Sayed, and Yasser Hassan. "Influence of vertical alignment on horizontal curve perception: effect of spirals and position of vertical curve." Canadian Journal of Civil Engineering 32, no. 1 (February 1, 2005): 204–12. http://dx.doi.org/10.1139/l04-090.
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Several studies have shown that the perception of horizontal curves can be influenced by an overlapping vertical alignment. A previous two-phase study investigated the hypothesis that a horizontal curve appears flatter when overlapping with a vertical sag curve and sharper when overlapping with a vertical crest curve. The study concluded that the hypothesis was valid. The study also developed several statistical models to estimate the perceived radius of horizontal curves in a combined alignment. This study extends the earlier work by investigating the effect of additional geometric parameters on the perception. The parameters examined include the presence of spiral curves, the length of the spirals, and the position of the vertical curve midpoint relative to the horizontal curve. It was found that (1) driver misperception of the horizontal curvature increases as the radius of the horizontal curve increases, (2) the presence of a spiral curve affects driver perception of the horizontal curvature in the case of crest combination only, (3) the length of the spiral curve has no effect on the perception whether on crest or sag combinations, and (4) while the effect of the position of the vertical curve midpoint relative to the horizontal curve is not statistically significant, it seems that the perception problem appears to diminish as the positive offsets increases.Key words: highway geometric design, visual perception, combined alignment.
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Zhao, Liang, and Meng Li Zhang. "Influence of Radius of Horizontal Curve on Driver's Psychology and Physiology on the Two-Lane Mountain Highway." Applied Mechanics and Materials 226-228 (November 2012): 2335–39. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.2335.
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At the present time, the accident remains at a high level all over the world. It mostly happened on the two-lane mountain highway. Through analysis of the relationship between radius of horizontal curve and driving safety of the drivers on two-lane mountain highway, variations of heart rate was be introduced. The variations of heart rate will be changed with Radius of horizontal curve through qualitatively and quantitatively analysis. However, the maximum of drivers' heart rate does not occur on the limit radius of horizontal curve. It locates at the place slightly larger than the limit radius of horizontal curve. The model between heart rate variation and radius of horizontal curve square was established. Finally, some useful advises were suggested to strengthen the two-lane highway management.
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Easa, Said, and Essam Dabbour. "Establishing design guidelines for compound horizontal curves on three-dimensional alignments." Canadian Journal of Civil Engineering 32, no. 4 (August 1, 2005): 615–26. http://dx.doi.org/10.1139/l05-016.
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In current design guides, the minimum radii of compound horizontal curves are based on the design requirements of simple horizontal curves for each arc on flat terrain. Such a design ignores the effects of compound curvature and vertical alignment. This paper uses computer simulation software to establish the minimum radius requirements for compound curves, considering these effects. The actual lateral acceleration experienced by a vehicle negotiating a two-dimensional (2-D) simple curve is recorded as a base scenario to facilitate the analysis of a compound curve on a flat terrain or combined with vertical alignment (three-dimensional (3-D) compound curves). The vertical alignments examined include upgrades, downgrades, crest curves, and sag curves. Mathematical models for minimum radius requirements were developed for flat and 3-D compound curves. Three types of design vehicles were used. The results show that an increase in the minimum radius ranging from 5% to 26% is required to compensate for the effects of both compound curvature and vertical alignment.Key words: highway geometric design, compound horizontal alignments, side friction, vehicle simulation, 3-D alignments.
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Zheng, Binshuang, Xiaoming Huang, Junyao Tang, Jiaying Chen, Runmin Zhao, Zhengqiang Hong, Tao Tang, and Meiling Han. "Evaluation on Braking Stability of Autonomous Vehicles Running along Curved Sections Based on Asphalt Pavement Adhesion Properties." Journal of Advanced Transportation 2022 (May 29, 2022): 1–20. http://dx.doi.org/10.1155/2022/7348554.
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As the main objective influencing factor on the brake safety of autonomous vehicles, pavement texture information is directly related to road surface antiskid performance. However, in the brake system of autonomous vehicles, the influence of road surface adhesion characteristics on braking stability is seldomly considered. To study the braking stability of autonomous vehicles on curved sections under different road conditions, the advanced close-range photogrammetry system was utilized to extract the road surface texture information. Thereafter, the power spectral density (PSD) of the road surface was calculated by MATLAB to obtain the pavement adhesion coefficient curves based on the Persson friction theory model under different road conditions. Considering the pavement adhesion characteristics, the braking model of autonomous vehicles was built in Simulink, and then, the braking performance on curved sections was analyzed with CarSim/Simulink cosimulation. The results indicate that, according to the adhesion coefficient of different asphalt pavement types under different road conditions, the ranking order is open-grade friction course (OGFC) > stone matrix asphalt (SMA) > dense-graded asphalt concrete (AC). In addition, both the maximum lateral offset distances and the maximum lateral forces of the tires decrease as the curve radius gradually increases under different road conditions. It can also be found that there is a relatively uniform vertical forces distribution of the tire when the curve radius is no less than 100 m, and the limit speed of the vehicle varies parabolically with increasing in curve radius. Compared with dry road, the reduction of vehicle braking deceleration is more significant and the yaw rate is greater on wet road. Last but not least, the braking comfort with a radius of 200 m is the best according to the comfort index (CI) in International Standard ISO, in which the comfort level can be sorted into six levels.
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Li, Rong Bin, and Can Cui. "Comparison and Research of Thermocouple Measuring Temperature Curve and Theoretical Temperature Curve in Grinding." Applied Mechanics and Materials 454 (October 2013): 280–87. http://dx.doi.org/10.4028/www.scientific.net/amm.454.280.
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A Thermocoupletemperature measurement test of grinding for steel 45 was done to analyse thereason of errors between experimental temperature curve and theoreticaltemperature curve derived by triangular distribution heat source model.It wasshown that,errors of influencing factors,such as grinding heat flow,thermalconductivity,density,specific heat capacity,limited grinding energy andeffective abrasive contact radius,have certain effect on temperature measuredby thermocouple.It was found that the influence of grinding heat flow into aworkpiece is the biggest and the effective radius of abrasive contact thesmallest.It is concluded that as long as the error of each influencing factoris controlled in a certain range,thermocouple measuring temperature curve willmatch with theoretical temperature curve closely.
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Shen, Peng, Cai Yun Wang, Zhong Wen, and Qi Yue Liu. "An Experimental Investigation on Railway Adhesion Properties under Water Medium and Dry Condition Respectively." Advanced Materials Research 189-193 (February 2011): 3554–59. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3554.
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The effect of wheel speed, axle load and track curve radius on wheel/rail adhesion properties under dry and water medium condition was investigated in this paper using JD-1 wheel/rail simulation facilities with Hertz simulation method, and then testing method of “four horizontals and three factors” was adopted to analyze the influence degree of speed, axle load and track curve radius on wheel/rail adhesion. Results from the experiment are that: The adhesion coefficient reached maximum at creep ratio of 1.5% under dry condition, and 1% under wet condition respectively; the adhesion coefficient under water medium condition occupy about a proportion of 32%-50% of that under dry condition. adhesion coefficient would reduce with speed increasing, axle load increasing and track curve radius decreasing under dry condition, and reduce with speed increasing, axle load decreasing and track curve radius decreasing under water medium condition; As far as influence degree of three testing factors which have effect on adhesion coefficient is concerned, axle load is the first one, then speed, finally track curve radius under dry condition, and speed is the first one, then axle load, finally track curve radius under water medium condition.
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Hauser, Vladimír, Olena S. Nozhenko, Kateryna O. Kravchenko, Mária Loulová, Juraj Gerlici, and Tomáš Lack. "Innovative wheel tread design aimed to tramcar-track interaction improvement when passing curves of a small radius." MATEC Web of Conferences 157 (2018): 03010. http://dx.doi.org/10.1051/matecconf/201815703010.
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Tramways in cities often ride in track curves of a small radius, which is followed by an increased effect of the vehicle on the track. In the rail - wheel contact often occurs creep in longitudinal as well as in lateral direction, which causes increase of riding resistance, wear in rail – wheel contact and noise operation. Exactly with the aim to reduce these undesirable effects we designed a tram bogie with steered wheelsets and with the double wheel tread. This inventions are registered by authors under Utility Model Nr. u201609015 and Patent Application Nr. a201701589. Description of proposed process of passing vehicle through strongly curved track is given in this paper. A comparison of creep velocities in rail - wheel contact results obtained by computer multibody simulations for a tram vehicle riding through a S-curve are presented. Purposefulness of proposed invention is investigated by constructing vehicle ride resistance dependence to the track curve radius.
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Wang, Cai Yun, Peng Shen, and Qi Yue Liu. "Study on Using Numerical Method to Predict Wear Volume of Rail." Advanced Materials Research 335-336 (September 2011): 339–42. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.339.
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This paper describes an numerical method and simulation experiment investigation on the rail wear affected by the curve radius and axle load etc. the effects of curve radius and axle load on The effects of axle load and curve radius on total slippage of contact particles and friction work of wheel/rail are investigated with numerical methods are analyzed by kalker’s program CONTACT. The effect of curve radius and axle load on rolling wear behaviour of rail is investigated by simulation experiment. It is indicated that axle load and curve radius are important factors to effect rolling contact wear of wheel-rail, and there is a linear relationship between wear volume of rail and friction work of wheel/rail; The preliminary empirical formula between wear volume of rail sample and friction work is given by analysis the experimental and calculation results, the formula offers a certain reference value for researching wear of wheel-rail and predicting wear volume of rail.
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Dias, Charitha, Takashi Oguchi, and Kasun Wimalasena. "Drivers’ Speeding Behavior on Expressway Curves: Exploring the Effect of Curve Radius and Desired Speed." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 17 (June 17, 2018): 48–60. http://dx.doi.org/10.1177/0361198118778931.
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Speed profiles can be considered as a key input for assessing safety, comfort and efficiency of highway or expressway segments. Therefore, understanding drivers’ speeding behavior, particularly on expressway curve sections, is important. Most previous studies have modeled the speed on highway curve sections mainly as constant or a piecewise linear profile. Such approaches may not realistically represent the properties of speed and acceleration behavior. Furthermore, mechanisms underlying the speeding behavior through curve sections have not been comprehensively studied. In this study, the minimum-jerk concept, which was originally applied in neuroscience and robotics domains, is utilized to explore drivers’ speeding behavior on expressway curve sections. GPS-based naturalistic driving data of vehicles travelling on the Tomei expressway in Japan under free-flow conditions were used to explore the applicability and validity of the proposed approach. How the proposed approach can be used to evaluate the effect of horizontal geometry and desired driving speed on drivers’ speeding and acceleration behavior on expressway curve sections is also discussed. The findings of this study could be useful in modeling speed and acceleration choice behaviors on highway curve sections which could potentially be applied in highway design consistency evaluations. Furthermore, the outputs of this study may be useful in other advanced applications, such as modeling and visualizing realistic vehicle movements in driving simulators and virtual reality applications and trajectory planning of autonomous vehicles.
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Dong, Yaping, Jinliang Xu, Menghui Li, Xingli Jia, and Chao Sun. "Association of Carbon Emissions and Circular Curve in Northwestern China." Sustainability 11, no. 4 (February 22, 2019): 1156. http://dx.doi.org/10.3390/su11041156.
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Carbon emissions, produced by automobile fuel consumption, are termed as the key reason leading to global warming. The highway circular curve constitutes a major factor impacting vehicle carbon emissions. It is deemed quite essential to investigate the association existing between circular curve and carbon emissions. On the basis of the IPCC carbon emission conversion methodology, the current research work put forward a carbon emission conversion methodology suitable for China’s diesel status. There are 99 groups’ test data of diesel trucks during the trip, which were attained on 23 circular curves in northwestern China. The test road type was key arterial roads having a design speed greater than or equal to 60 km/h, besides having no roundabouts and crossings. Carbon emission data were generated with the use of carbon emission conversion methodologies and fuel consumption data from field tests. As the results suggested, carbon emissions decline with the increase in the radius of circular curve. A carbon emission quantitative model was established with the radius and length of circular curve, coupled with the initial velocity as the key impacting factors. In comparison with carbon emissions under circular curve section and flat section scenarios, the minimum curve radius impacting carbon emissions is 500 m. This research work provided herein a tool for the quantification of carbon emissions and a reference for a low-carbon highway design.
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Zeng, Wei, Yue Yang, Wen-Sheng Qiu, Huan Xie, and Su-Chao Xie. "Optimization of the target profile for asymmetrical rail grinding in sharp-radius curves for high-speed railways." Advances in Mechanical Engineering 9, no. 2 (February 2017): 168781401668719. http://dx.doi.org/10.1177/1687814016687196.
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Asymmetrical rail grinding in sharp-radius curves could reduce the side wear of railheads and enhance curve capacity of rail vehicles. The wheel/rail contact performance and curve capacity could be further improved by the optimization of the asymmetrical rail grinding target profile. In order to modify the target profile smoothly, the nonuniform rational B-spline curve with adjustable weight factors is used to establish a parameterized model of railhead curves in the asymmetrical grinding region. The indices of contact performance and curve capacity for different weight factors are obtained using experiment design and service performance simulation. Two Kriging surrogate models are proposed, in which the design variables are the adjustable weight factors, and the response parameters are the indices of contact performance and curve capacity, respectively. The multi-objective optimization model of the target profile is established, in which the objective functions are the two Kriging surrogate models of contact performance and curve capacity. The optimized weight factors are sought using a nondominated sorting genetic algorithm II, and the corresponding optimal target profile is obtained. The wheel/rail service performance simulation before and after optimization indicates that the contact performance and curve capacity are improved significantly.
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Ibragimov, S. A. "Investigation of the dependences of the Vivaldi antenna with two curve radii in the electrodynamic modeling software package." Herald of Dagestan State Technical University. Technical Sciences 49, no. 1 (May 20, 2022): 49–58. http://dx.doi.org/10.21822/2073-6185-2022-49-1-49-58.
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Objective. The aim of the study is to build and optimize a computer model of the antenna using software packages for electrodynamic modeling.Method. The study is based on dynamic modeling methods.Result. In this paper, the dependences of the width of the radiation pattern on the curved Vivaldi antenna with a mirror arrangement of the petals are obtained. Graphs of the dependence of the radii of curved petals and aperture values on the width of the radiation pattern in two planes for frequencies of 3 and 24 GHz are plotted. Curve radius, antenna aperture and lower antenna height are plotted as functions of the maximum beamwidth for 24 GHz and the minimum beamwidth for 3 GHz. The obtained dependencies were approximated for two planes θ = 900 (antenna aperture plane) and φ = 00 (plane perpendicular to the antenna aperture plane). By means of regression analy sis, analytical descriptions and graphs of dependences of the maximum beamwidth for 24 GHz and the minimum beamwidth for 3 GHz, on the radii of the curves, aperture and the height of the lower curve of the antenna lobe were obtained.Conclusion. The resulting mathematical model makes it possible to obtain the values of the radius of the curve, the opening and the lower height of the antenna lobes for different frequencies, as a result, to build a Vivaldi antenna with the desired topology.
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Lian, Guofu, Yang Zhang, Hao Zhang, Xu Huang, Changrong Chen, and Jibin Jiang. "Investigation of Geometric Characteristics in Curved Surface Laser Cladding with Curve Path." Metals 9, no. 9 (August 29, 2019): 947. http://dx.doi.org/10.3390/met9090947.
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Laser cladding on curved surfaces is essential in industrial applications for restoration and remanufacturing of high-value parts. This study investigated the influence of different factors on clad width, clad height, and dilution rate in curved surface laser cladding with curved path. Mathematical models were developed using central composite designs to predict these geometric characteristics by controlling laser power, scanning speed, gas flow, and altering the outside radius of the cylindrical substrate. Analysis of variance and response surface methodology indicated that clad width increased with increasing laser power and reducing scanning speed. Clad height positively correlated to laser power and negatively correlated to the outside radius of the cylindrical substrate. Increasing the laser power while decreasing the scanning speed led to an increase in dilution rate. Afterwards, the geometric characteristics of the clad were improved by optimizing these factors with the target to maximize clad width and height as well as to minimize dilution rate. The difference between model predictions and experimental validations for clad width, clad height, and dilution rate were 3.485%, 3.863%, and 6.566%, respectively. The predicted accuracy was verified with these models, and they were able to provide theoretical guidance to predict and control the geometric characteristics of curved surface laser cladding with a curved path.
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Rondora, Maria Emilia Schio, Ali Pirdavani, and Ana Paula C. Larocca. "Driver Behavioral Classification on Curves Based on the Relationship between Speed, Trajectories, and Eye Movements: A Driving Simulator Study." Sustainability 14, no. 10 (May 20, 2022): 6241. http://dx.doi.org/10.3390/su14106241.
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Horizontal curves of rural highways are prone to a considerably high number of fatalities because an erroneous perception can lead to unsafe driving. This generally occurs when a driver fails to notice the highway geometry or changes in the driving environment, particularly curved segments. This study aimed to understand the geometric characteristics of curved segments, such as radius and approach tangents, on the driving performance towards minimizing vehicle crashes. Speed profiles and lateral position, the most common indicators of successful negotiation in curves, and eye movements were recorded during an experiment conducted in a fixed-base driving simulator equipped with an eye-tracking system with a road infrastructure (a three-lane highway) and its surroundings. A driving simulator can faithfully reproduce any situation and enable sustainable research because it is a high-tech and cost-effective tool allowing repeatability in a laboratory. The experiment was conducted with 28 drivers who covered approximately 500 test kilometers with 90 horizontal curves comprising nine different combinations of radii and approach tangent lengths. The drivers’ behavior on each curve was classified as ideal, normal, intermediate, cutting, or correcting according to their trajectories and speed changes for analyses of the performance parameters and their correlation conducted by factorial ANOVA and Pearson chi-square tests. The cross-tabulation results indicated that the safest behavior significantly increased when the curve radius increased, and the performance measures of curve radii were greatly affected. However, the driving behavior was not affected by the approach tangent length. The results revealed segments of the road that require a driver’s closer attention for essential vehicle control, critical information, and vehicle control in different parts of the task.
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Fitzpatrick, Kay, C. Brian Shamburger, Raymond A. Krammes, and Daniel B. Fambro. "Operating Speed on Suburban Arterial Curves." Transportation Research Record: Journal of the Transportation Research Board 1579, no. 1 (January 1997): 89–96. http://dx.doi.org/10.3141/1579-11.
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Free-flow speeds were collected at both a control section and a curve section at 14 surburban sites with horizontal curves and 10 suburban sites with vertical curves. The scatter plots of the 85th percentile speed versus approach density indicate that when the approach density is between 3 and 15 approaches per km, approach density does not influence speed. Regression analysis indicated that the curve radius for horizontal curves and the inferred design speed for vertical curves can be used to predict the 85th percentile speed on curves for vehicles on the outside lane of a four-lane divided suburban arterial. For horizontal-curve sites, a curvilinear relationship exists between curve radius and the 85th percentile speed. A linear relationship provided the best fit between the inferred design speed and the 85th percentile speed for the vertical curve sites. For the horizontal and vertical curve sites, the speed at which 85th percentile speed becomes less than the inferred design speed is lower for suburban arterials than for rural highways. Drivers on suburban horizontal curves operate at speeds greater than the inferred design speed for curves designed for speeds of 70 kph or less, whereas on rural, two-lane roadways, drivers operate at speeds greater than the inferred design speed for curves designed for speeds of 90 kph or less. For vertical curves, the speeds at which drivers operate greater than the inferred design speed are 90 kph for suburban arterials and 105 kph for rural highways. These results are within 12 kph of the observed 85th percentile speeds on nearby control sections (approximately 80 kph for suburban arterials and 100 kph on rural highways).
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Šeporaitis, Mindaugas, Viktoras Vorobjovas, and Audrius Vaitkus. "Evaluation of Horizontal Curve Radius Effect on Driving Speed in Two Lane Rural Road. Pilot Study." Baltic Journal of Road and Bridge Engineering 15, no. 4 (September 28, 2020): 252–70. http://dx.doi.org/10.7250/bjrbe.2020-15.503.
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This paper presents a case study of driving speed at horizontal curves in the regional road. The literature review of operating speed at horizontal curves in regional roads expresses the difference between design speed and driving speed. Driving speed was measured in ten horizontal curves on regional road No. 2610. Collected data was compared to the design speed, various design standards, and Operating Speed Prediction Models for traffic in low-volume roads. Based on result analysis, was proposed initial adjusted minimum radius of the horizontal curve based on operating speed. It is justified that proposed corrections based on operating speed ensure a credible speed limit effect on road safety. The performed experiment showed different tendencies comparing measured driving speed with permitted and design speeds. It was determined that dependent on specific curved section drivers tend to exceed posted speed limit from 17% to 98% of cases, and from 41% to 100% − the design speed in the horizontal curve. This research led to identifying the limitations of experimental research methodology. These limitations are related to experimental Site selection with different combinations of alignment elements, traffic, and accident data. A pilot study showed significant results and gave essential insights into the full-scale research plan. The results are expected to benefit both other researchers and the organisations responsible for the development and implementation of normative technical documents for road design.
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Sharf Aldeen, Asame, Ali Abdi Kordani, Seyed Mohsen Hosseinian, and Mehdi Mehdi Nazar. "Evaluation of the Application of Maximum Radius in Horizontal Curves Using Vehicle Dynamic Simulation." Advances in Civil Engineering 2022 (March 22, 2022): 1–19. http://dx.doi.org/10.1155/2022/5237541.
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Most road design standards recommend using a spiral curve for transitions. The main advantages of using this curve are the gradual increase in the centrifugal force, creating a suitable space for presenting superelevation, and providing a correct perception of the curve for the driver. In this research, vehicle dynamic simulation software CarSim and TruckSim is used to assess the forces imposed on the vehicles. In this regard, 360 scenarios are considered for sedans, SUVs, and trucks, which consist of variations of the road geometry (simple or spiral horizontal curve), curve radius, and type and speed of the vehicle. In addition, the regression analysis is performed to examine the relationships between the lateral acceleration (as a dependent variable) and the vehicle speed, curve radius, and vehicle type (as independent variables). The results indicate that in all cases, safety in the spiral horizontal curve is greater than that in the simple horizontal curve, and the maximum side friction factor, lateral acceleration, roll rate, roll angle, yaw rate, and lateral distance in the simple horizontal curve are higher than those in the spiral horizontal curve. Moreover, the difference percentage of the side friction factor, lateral acceleration, yaw rate, and lateral distance between the simple and spiral horizontal curves is the highest in SUVs, followed by sedans and trucks, while the difference percentage of the roll rate and roll angle is the highest in sedans, followed by SUVs and trucks. The results of regression analysis illustrate that the coefficient of determination (R2) in the proposed model is 0.972, 0.964, and 0.981 for sedans, SUVs, and trucks, respectively, indicating the strong relationships between the dependent and the explanatory variables as well as the capability of the model to cover the data.
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Bruce, J. W., and P. J. Giblin. "Growth, motion and 1-parameter families of symmetry sets." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 104, no. 3-4 (1986): 179–204. http://dx.doi.org/10.1017/s030821050001917x.
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SynopsisAssociated to every plane curve there is the locus of centres of circles bitangent to that curve, the so-called symmetry set of the curve. We can view this set as the spine of our curve, which can be recovered by taking the envelope of circles of varying radii along this spine. Varying the symmetry set in some isotopy while keeping the radius function fixed may be viewed as crudely modelling motion of the original curve viewed as a biological object. Fixing the symmetry set and varying the radius function can be considered to model growth crudely. In this paper we shall describe the generic changes in the curves which take place in the process of growth and motion, and outline the corresponding results for spheres centred on a space curve. We also use the idea of a stratified Morse function to describe the generic changes which occur in one parameter families of (full) bifurcation sets in the plane. Applying this to the bifurcation set of distance squared functions we find all the transitions of a symmetry set (and evolute) which occur in a generic isotopy of a plane curve.
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Koc, Władysław. "Extending transition curve in analytical design method." Transportation Overview - Przeglad Komunikacyjny 2016, no. 4 (April 1, 2016): 1–12. http://dx.doi.org/10.35117/a_eng_16_04_01.
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The paper presents the problem of extending the transitional curves, using for this purpose an analytical design method. The basis for the analysis of numerical calculations were carried out for a wide set of parameters characterizing the standard geometric system. We considered an importance of the size of radius of the circular arc and return angle of route on the obtained results after the formulation of appropriate theoretical dependence. It was found that the extension of the transition curve does not need cause large lateral displacements of the existing track at considerable length. It is only necessary to reduce the radius of the circular arc in a suitable way.
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Biswas, Asish, and Madhab Chandra Ghosh. "Performance analysis of female sprinters in different curve radius." International Journal of Physical Education, Sports and Health 8, no. 1 (January 1, 2021): 147–51. http://dx.doi.org/10.22271/kheljournal.2021.v8.i1c.1983.
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You, Qing Chong, and Said M. Easa. "Roadside-curve lateral offsets for roadway reverse horizontal curves with intermediate tangents." Canadian Journal of Civil Engineering 47, no. 4 (April 2020): 382–94. http://dx.doi.org/10.1139/cjce-2018-0547.
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Following the roadside design curve of a spiraled roadside curve (SRC) previously proposed by the authors, this paper examines the characteristics of the required lateral offset ratios defined by the SRC on roadway reverse horizontal curves, including two reverse spiraled horizontal curves with and without an intermediate tangent. The radius ratio of two reverse simply horizontal curves, the spiral curve lengths of two reverse spiraled horizontal curves, and the intermediate tangent length were found to be the major influential factors of the offset ratios. A complete set of design tables was developed for reverse simple horizontal curves and reverse spiraled horizontal curves respectively, which would have significant engineering implications to roadside design of roadway reverse horizontal curves.
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Peiyong, Li, Gao Feng, Wang Chengfang, Mao Yunsheng, and Cui Jin. "Research of the Curve Radius of Shape Formed in Profile Cold Forming with BP Neural Networks Approach Based on Experiment." Journal of Ship Production and Design 32, no. 01 (February 1, 2016): 50–58. http://dx.doi.org/10.5957/jspd.2016.32.1.50.
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During the processing of frame part forming in ship production, the prediction of the curve radius of shape formed is of great significance for the quality and efficiency of forming work. The experiment method is used to conduct the research. Because the profile forming is affected by various factors, this article used orthogonal experiment designing method to draw up the forming experiment scheme. In the experiment researches, the angle steel is chosen as study object. Using the data recorded in the experiments as training sample, this article established a model based on the Bayesian regularization back propagation (BP) neural network to predict the curve radius of shape formed. With this model and the test sample recorded in the experiment, the calculation results showed that the model could reflect the relationship between the technical parameters and the curve radius correctly. Using the above model, this article predicts the curve radius with a series of variables of the influence factors, studies the rules of the influence of the factors to the curve radius, and obtains meaningful conclusions. These conclusions have been applied to guide the development of the three-fulcrum frame bender successfully.
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Sil, Gourab, Avijit Maji, Suresh Nama, and Akhilesh Kumar Maurya. "OPERATING SPEED PREDICTION MODEL AS A TOOL FOR CONSISTENCY BASED GEOMETRIC DESIGN OF FOUR-LANE DIVIDED HIGHWAYS." Transport 34, no. 4 (July 17, 2019): 425–36. http://dx.doi.org/10.3846/transport.2019.10715.
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Researchers have studied two-lane rural highways to predict the operating speed on horizontal curves and correlated it with safety. However, the driving characteristics of four-lane-divided highways are different. Weak lane discipline is observed in these facilities, which influences vehicle speed in adjacent lane or space. So, irrespective of its lane or lateral position, vehicles in four-lane divided highways are considered free flowing only when it maintains the minimum threshold headway from any lead vehicle. Examination of two conditions is proposed to ensure the free flow. Vehicles meeting both conditions, when tracked from the preceding tangent section till the centre of the horizontal curve, are considered as free flowing. The speed data of such free flowing passenger cars at the centre of eighteen horizontal curves on four-lane divided highways is analysed to develop a linear operating speed prediction model. The developed model depends on curve radius and preceding tangent length. The operating speed of passenger car in four-lane divided highways is influenced by horizontal curve of radius 360 m or less. Further, longer tangent would yield higher operating speed at the centre of the curve. Finally, two nomograms are suggested for conventional design, consistency based design and geometric design consistency evaluation of four-lane divided horizontal curves.
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Xin, Chunfu, Zhenyu Wang, Chanyoung Lee, and Pei-Sung Lin. "Modeling Safety Effects of Horizontal Curve Design on Injury Severity of Single-Motorcycle Crashes with Mixed-Effects Logistic Model." Transportation Research Record: Journal of the Transportation Research Board 2637, no. 1 (January 2017): 38–46. http://dx.doi.org/10.3141/2637-05.
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Horizontal curves have been of great interest to transportation researchers because of expected safety hazards for motorcyclists. The impacts of horizontal curve design on motorcycle crash injuries are not well documented in previous studies. The current study aimed to investigate and to quantify the effects of horizontal curve design and associated factors on the injury severity of single-motorcycle crashes with consideration of the issue of unobserved heterogeneity. A mixed-effects logistic model was developed on the basis of 2,168 single-motorcycle crashes, which were collected on 8,597 horizontal curves in Florida for a period of 11 years (2005 to 2015). Four normally distributed random parameters (moderate curves, reverse curves, older riders, and male riders) were identified. The modeling results showed that sharp curves (radius <1,500 ft) compared with flat curves (radius ≥4,000 ft) tended to increase significantly the probability of severe injury (fatal or incapacitating injury) by 7.7%. In total, 63.8% of single-motorcycle crashes occurring on reverse curves are more likely to result in severe injury, and the remaining 26.2% are less likely to result in severe injury. Motorcyclist safety compensation behaviors (psychologically feeling safe, and then riding aggressively, or vice versa) may result in counterintuitive effects (e.g., vegetation and paved medians, full-access-controlled roads, and pavement conditions) or random parameters (e.g., moderate curve and reverse curve). Other significant factors include lighting conditions (darkness and darkness with lights), weekends, speed or speeding, collision type, alcohol or drug impairment, rider age, and helmet use.
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Zeng, Xiaohui, Han Wu, Jiang Lai, and Hongzhi Sheng. "Hunting stability of high-speed railway vehicles on a curved track considering the effects of steady aerodynamic loads." Journal of Vibration and Control 22, no. 20 (August 9, 2016): 4159–75. http://dx.doi.org/10.1177/1077546315571986.
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Aerodynamic loads may have effects on the hunting stability, and the factor of curved track makes it more complicated. Therefore, considering the steady aerodynamic loads generated by crosswind and airflow in the opposite advancing direction of train, the hunting stability of high-speed railway vehicle on a curved track is studied in this paper. The changes of gravitational restoring force and creep coefficients which are caused by aerodynamic loads are considered, and the change of equilibrium position due to aerodynamic loads, centrifugal force and the factor of curved track is also in consideration. A mathematical model of a high-speed railway vehicle during curve negotiation with aerodynamic loads is set up. A program based on the model is written and verified. Using this program, the linear critical speed considering the effects of aerodynamic loads is determined by the eigenvalue analysis. This paper investigates the critical speeds in three aerodynamic conditions. Considering the aerodynamic loads, the dependence of critical speed on curve radius and super-elevation is analyzed, and the impact of aerodynamic loads on instability mode is analyzed as well. In addition, this paper obtains the dominant factors affecting critical speed and the variation tendency of critical speed with primary longitudinal stiffness by orthogonal experiments. The results show that the critical speed decreases or increases while the wind is blowing to outer rail or inner rail respectively. The aerodynamic loads produce obvious effects on the instability mode. The variation tendency of critical speed dependence on curve radius in the conditions with aerodynamic loads keeps consistent with the case without aerodynamic loads. It is seen from the orthogonal experiments that, aerodynamic loads and curve radius are the dominant factors affecting linear critical speed of vehicle on a curved track, and the linear critical speed decreases with the increasing of primary longitudinal stiffness.
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Zhong, W., P. Chen, and Y. Wang. "An Experimental Investigation on Wear of Rail in Different Curve Radius." Advanced Materials Research 739 (August 2013): 458–61. http://dx.doi.org/10.4028/www.scientific.net/amr.739.458.
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Among the rail defects, the transverse fatigue crack, which has been the most dangerous damage, is developed near the rail running face and grows perpendicular to the rail surface. Finally, the transverse fatigue crack would result in the failure of railway rail. In this paper, the rolling tests were performed using a JD-1 wheel/rail simulation facility without any lubricant. The tester is composed of a small wheel served as rail and a larger wheel served as wheel. The fatigue behavior of rail rollers with different materials and curve radius were investigated in detail by examining wear volume and wear scar using optical microscopy (OM) and scanning electronic microscopy (SEM). The results indicate that with curve radius decreasing, the wear volume of rail roller increases rapidly and the fatigue damage becomes severe. Furthermore, the cracking propagation angle increases obviously with curve radius decreasing and fatigue wear is dominating during the wear process. There appears distinct plastic deformation on the section of rail roller under small curve radius condition. For the same curve radius, the wear volume of PD3 rail is more than that of PG4 rail and the plastic deformation is more obvious. Moreover, the cracking propagation angle of PD3 rail material is smaller than that of PG4 rail. In conclusion, PG4 rail material is not suitable for the high-speed railway.
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Ligo, Richard G., and Oguz C. Durumeric. "Conformal transformations and curvature." Journal of Knot Theory and Its Ramifications 28, no. 02 (February 2019): 1950020. http://dx.doi.org/10.1142/s0218216519500202.
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In this paper, we discuss the relationship between conformal transformations of [Formula: see text] and the curvature of curves. First, for any non-circular closed curve, there exists a length-preserving inversion such that the maximum pointwise absolute curvature can be made arbitrarily large. In contrast, we show that the total absolute curvatures of a family of curves conformally equivalent to a given simple or simple closed curve are uniformly bounded. Furthermore, we show that the total absolute curvature of an inverted regular [Formula: see text] simple closed curve as a function of inversion center and radius is removably discontinuous along the curve with exactly a [Formula: see text] drop, and continuous elsewhere.
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Zhao, HaiLong, Ke Peng, ZePing Wu, WeiHua Zhang, JiaWei Yang, and JingBo Sun. "Numerical Simulation of Supersonic Carman Curve Bodies with Aerospike." International Journal of Aerospace Engineering 2021 (April 28, 2021): 1–14. http://dx.doi.org/10.1155/2021/8821721.
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Drag reduction is one of the important problems for the supersonic vehicles. As one of the drag reduction methods, aerospike has been used in some equipment because of its good drag reduction effect. In this paper, the numerical simulations of Carman curve bodies with different lengths of the aerospike and different radius of the flat cylindrical aerodisk in supersonic flow freestream are investigated. Based on the numerical simulations, the mechanism of drag reduction of the aerospike is discussed. The drag reduction effect influence of the parameters of the aerodisk radius and the aerospike length on the Carman curve body is analyzed. The aerodisk radius within a certain range is helpful for the drag reduction. The change of length of the aerospike has little effect on the drag of Carmen curve bodies. The drag reduction effect of the same aerospike becomes worse with the increase of the incoming Mach number.
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Bhat, Vishesh S., and R. Haribaskar. "A pair of kinematically related space curves." International Journal of Geometric Methods in Modern Physics 15, no. 10 (October 2018): 1850180. http://dx.doi.org/10.1142/s0219887818501803.
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We investigate the relation between two types of space curves, the Mannheim curves and constant-pitch curves and primarily explicate a method of deriving Mannheim curves and constant-pitch curves from each other by means of a suitable deformation of a space curve. We define a “radius” function and a “pitch” function for any arbitrary regular space curve and use these to characterize the two classes of curves. A few non-trivial examples of both Mannheim and constant pitch curves are discussed. The geometric nature of Mannheim curves is established by using the notion of osculating helices. The Frenet–Serret motion of a rigid body in theoretical kinematics is studied for the special case of a Mannheim curve and the axodes in this case are deduced. In particular, we show that the fixed axode is developable if and only if the motion trajectory is a Mannheim curve.
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Echaveguren, Tomás, Marcelo Bustos, and Hernán de Solminihac. "Assessment of horizontal curves of an existing road using reliability concepts." Canadian Journal of Civil Engineering 32, no. 6 (December 1, 2005): 1030–38. http://dx.doi.org/10.1139/l05-056.
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Horizontal curves on road are commonly analyzed under design speed point of view, where it is assumed that the maximum speed of a vehicle in a curve is the design speed. The empirical evidence has demonstrated that when the design speed is low, the operating speed tends to be higher. This happens because of an available remaining lateral (or transverse) friction for speeds over design speed. This condition is determined by a speed limit, obtained from the demand and supply equilibrium of friction of a pavement. The difference between operating and design speeds is usually considered as the margin of safety of a horizontal curve on a road. In this study, a methodology to determine the margin of safety of an existing curve is proposed. The methodology is based on the reliability theory by which reliability of operational conditions can be analyzed by using a reliability index as a margin of safety. A case study for light vehicles is evaluated to determine high impact variables over reliability, such as, macrotexture, skid resistance, curve radius, and superelevation. The results obtained in this study demonstrated that curve radius, skid resistance, and macrotexture are variables with high impact over failure probability. In constrast, superelevation has little effect on the failure probability.Key words: reliability, horizontal curves, operating speed, skid resistance, pavement texture.