交通运输工程学报

Micro-crack propagation behavior of pavement concrete subjected to coupling effect of fatigue load and freezing-thawing cycles

GUO Yin-chuan, SHEN Ai-qin, HE Tian-qin, ZHOU Sheng-bo

Abstract: In order to quantitatively characterize and analyze the evolution laws of pavement concrete internal cracks under the coupling effect of fatigue load and freezing-thawing cycles, the SEM and the morphological image segmentation method were used to extract the micro-crack patterns, the Image-Pro Plus was used to quantify the micro-crack structure, and the relationship between the crack parameters and the loss of flexural strength under the coupling effect was studied by using the grey correlation analysis method.Analysis result shows that there are original micro-cracks in pavement concrete, the average width is 13 μm, and the maximum length is 144 μm.Under the coupling effect, the evolution of pavement concrete cracks along the length direction is the alternative process of extension and fracture, while the crack evolution along thewidth direction is the alternative process of expansion and contraction.When the concrete is destroyed, the maximum length of crack reaches 352.64 μm, and the average width of crack reaches 15.4 μm.After 150 times freezing-thawing cycles, the crack area density increases significantly, and is 6.7 times larger than the density of original micro crack when concrete is destroyed.The flexural strength of pavement concrete is greatly related to the fractal dimension, average width and maximum length of the crack under the coupling effect, and the grey correlation coefficients are 0.957, 0.954 and 0.871 respectively.Based on the regression analysis, the equation between the flexural strength loss and crack structural parameters of pavement concrete is established, there is good linear correlation between the flexural strength loss and the fractal dimension, average width, maximum length of crack, and the correlation coefficients reach 0.97.More>

2016, 16(5): 1-9. doi: 10.19818/j.cnki.1671-1637.2016.05.001

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New design method of supplemented surface for airport turnoff taxiway

TAN Zhi-ming, YAO Yao, CHEN Jing-liang

Abstract: In order to simplify the design methods of supplemented surface bend on airport, the corresponding differential equation was established based on the turning track of landing gear tire when the plane glided on the runway, the gliding track was divided into two stages to solve the equation: nose wheel driving on the circular curve and nose wheel entering the straight section, and the analytical solution was obtained.The properties of supplemented surface for turning pavement were analyzed by introducing longitudinal space, position coefficient and supplemented width coefficient representing the widening value of supplemented surface for turning pavement.Based on the similarity of fillets width coefficients on different relative longitudinal distances and corner angles, the regression equation of fillets width coefficient was calculated, and the correctional formula of the angle between aircraft and exit line at the beginning of nose wheel entering the straight section was obtained.The new design method of supplemented surface for turning runway was put forward based on the differential equation solution of inner edge of supplemented surface on the circular curve, and was compared with ICAO method.Computationresult shows that when the turning angle is 135°, the curve radius is 45 m, the maximum wheelbase of plane is 25 m, and the width of main landing gear is 13 m, the adding width of supplemented surface calculated by using the new design method is 7.52 m, the value calculated by using ICAO method is 7.53 m, and the difference is less than 0.2%.When the cutoff point of curve is determined, any point coordinates of inner edge line of supplemented surface can be computed by using the new design method, while the inner edge line of supplemented surface must be determined in order to compute any point coordinates by using ICAO method.So, the calculated result of new method meets the precision and safety requirements, the calculation process is simple, and the use is easy.More>

2016, 16(5): 10-16. doi: 10.19818/j.cnki.1671-1637.2016.05.002

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Mechanical property of segmental tower of cable-stayed bridge

CHEN Kang-ming, WU Qing-xiong, HUANG Han-hui

Abstract: Based on the segmental tower of Waitan Bridge in Ningbo City, the axial compressive loading experiment of 1∶3.34scaled-model was conducted by using the prestressed steel strand self-balanced loading mode, and the force transferring route, mechanical characteristics, actual bearing capacity and local instability mechanism of segmental tower for cable-stayed bridge were studied by using finite element method and considering initial imperfections and local buckling.Analysis result shows that the external loads are mainly carried by the plates of two outer boxes, the stresses of the plates of outer and inner box increase and decrease from the sections closing to the abrupt changing section, the external load of inner box gradually transmits to outer box, and the maximum stresses of stiffened plates appear on the abrupt changing sections. The measurement points can be categorized into three kinds according to the relationship between the measured and sectional average stresses, including the points under axial compression and compression-flexure along the insider and outsider of steel box.The strength reduction coefficient of segmental tower is larger than 0.90 from the reduced-scale model experiment, and the ultimate bearing capacity of the model obtained by the finite element analysis is 1.06 times of theoretical ultimate bearing capacity.Although the local buckling of stiffened plates can be preventedeffectively by using longitudinal stiffeners and diaphragms, the attention should be paid to the design and construction of longitudinal stiffeners near the intersection of top plates, bottom plates and inner web plates of two side boxes, especially the longitudinal stiffeners close to the abrupt changing section, since the abrupt changing section easily leads to the stress concentration, and it is likely to occur local buckling.The stiffened plates of outsider of steel box for the segment model fail to resist larger applied loads due to the local buckling occurring on the abrupt changing section.More>

2016, 16(5): 17-29. doi: 10.19818/j.cnki.1671-1637.2016.05.003

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Modeling and simulation of railway vehicle wheel considering thermo-mechanical coupling

WEN Yong-peng, XU Xiao-jun, SHANG Hui-lin, LI Qiong

Abstract: Urban railway vehicle wheel was taken as research object, and an S-plate wheel model was established.The features of structural stress and thermal stress of wheel under different abrasions were investigated respectively by using FEM, the effects of thermo-mechanical coupling in the structure field and the thermal field on the stress characteristic of wheel were analysed, and the coupling rules of structural stress and thermal stress were obtained by considering thermomechanical coupling.Simulation result shows that the structural stress, the thermal stress and the coupling stress are all nonlinear with the development of tread abrasion of wheel.The coupling stress is stable when the wheel diameter ranges from 840 mm to 800 mm.When the diameter is less than 800 mm, the coupling stress grows faster, especially, when the diameter is 770 mm, the coupling stress rises rapidly.The coupling stress reaches 179.5 MPa under the abrasion-limit working condition.The coupling stress of wheel is produced by the superposition of complex three dimensional force system.For the coupling stress distribution, the phenomenonof drift exists at the position of the maximum coupling stress of wheel plate.The coupling stress of wheel plate becomes maximum at the brake end time, and is greater than both the maximum structural stress and the maximum thermal stress.Therefore, the coupling stress plays a leading role in the wheel stresses.For the structure design of wheel, it is recommended to consider the coupling role between the structural stress and the thermal stress, and to think the coupling stress as the evaluation index of wheel fatigue strength.More>

2016, 16(5): 30-41. doi: 10.19818/j.cnki.1671-1637.2016.05.004

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FEA of vibration response tolerance of traction transformer for high-speed train

YU Jin-peng, SONG Qing-peng, ZHANG Ming-yuan, ZHANG Ji-wang, LIU Xiao-xia, ZHANG Li-min

Abstract: In order to ensure the structure safety of lower body equipment for high-speed train, based on the simulation calculation method of vibration response tolerance and the Von Mises stress yield criterion, the vibration response capacities of high-speed train traction transformer under linear and nonlinear suspension stiffnesses were studied by using finite element simulation model.The longitudinal, horizontal and vertical loads were simultaneously applied to the traction transformer, and the dangerous node with the maximum response stress was gotten.The longitudinal, horizontal and vertical loads were respectively applied to the traction transformer, and the relationships between the amplitudes of different directions and the six stress componentsof dangerous node were obtained. Meanwhile, based on the superposition principle, the relationships between the amplitudes of different directions and the stress components of dangerous node under longitudinal, horizontal and vertical loads were obtained.The Von Mises stress function was computed, and the vibration response tolerance was obtained based on the Von Mises stress yield criterion.Analysis result shows that based on the superposition principle, the vibration response tolerance can be simulated and calculated by using MATLAB instead of ANSYS under the linear suspension stiffness.The avertical displacement contour curve is obtained between the vibration response tolerance surfaces under the linear and nonlinear suspension stiffnesses.When the coordinate point formed by the horizontal and longitudinal displacements is below the line projected by the vertical displacement contour curves, the vibration response tolerance of vertical displacement under the linear suspension stiffness is larger than the value under the nonlinear suspension stiffness.When the coordinate point formed by the horizontal and longitudinal displacements is above the line projected by the vertical displacement contour curves, the vibration response tolerance of vertical displacement under the linear suspension stiffness is smaller than the value under nonlinear suspension stiffness.More>

2016, 16(5): 42-48. doi: 10.19818/j.cnki.1671-1637.2016.05.005

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Evolution of wheel wear and dynamics performance of heavy haul freight car

LI Heng-li, LI Fei, WANG Xin-rui, YANG Ji-zhen

Abstract: The vehicle dynamics model considering wheel wear process was established based on a multi-body dynamics software of SIMPACK.The program of wheel/rail iterative automatic computation was programmed.Vehicle dynamics model, wheel/rail contact model, wheel/rail wear model, wheel/rail profile update and operation condition were integrated in the dynamics software.The subprogram embed in software SIMPACK was adopted to carry out the dynamics calculation and to organize the condition and data in wear process.The FASTSim algorithm was adopted to carry out the dynamics calculation of vehicle.Contact algorithm was adopted to carry out the wear calculation.The online automatic wear calculation cycle was formed without the co-simulation and data exchange of external program.Based on the operating environment ofDaqin Lines for the C80 B gondola, the evolution processes of wheel wear and dynamics performance during vehicle operation were studied. Analysis result indicates that the relationships between wheel tread wear depth, wheel full-section wear area and the operation mileage are both approximately linear, and wheel wear depth and wear area are about 1.68 mm and 100.63mm~2 per 100 000 km respectively.With the increase of operation mileage, the wheel wear and dynamics performance will deteriorates.With 250 000 km operation mileage, the vehicle lateral riding quality decreases from the "excellent"rank of new car to "good"rank, and the indexes of running safety such as derailment coefficient, wheel unloading rate and lateral wheelset force of negotiating, increase by at least 50% compared to new car.More>

2016, 16(5): 49-56. doi: 10.19818/j.cnki.1671-1637.2016.05.006

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Effect of ridgeline strengthening in thin-walled structure

ZHENG Yu-qing, ZHU Xi-chan, HU Qiang, LIU Jin

Abstract: The theoretical expressions of mean crushing force, energy absorbing prediction and ridgeline strengthening(RS)effect of thin-walled RS square tube were respectively derived out based on the ideal folding element model of square tube, the energy dissipation decomposition method during its plastic deformation process, and the modified energy balance equation of thinwalled RS square tube subjected to static axial crushing effect.A series of finite element models of thin-walled RS square tube subjected to quasi-static axial crushing were built, and imported into LS-DYNA program to conduct elastic-plastic dynamics simulation.The mean crushing forces were obtained, and the sensivity of ridgeline stress strengthening was investigated.The ridgeline strengthening technology was applied to the ridgeline strength design of front bumper beam and crashboxes for a vehicle.The corresponding thin-walled structures with higher strength steel were replaced by the assembly of ultra stress strengthened ridgelines and general mild steelplates.The finite element model of front bumper substructure system with strengthened ridgelines for individual evaluation was set up based on the existing finite element model verified by crash test.At 50km·h~(-1), the front crash simulation tests were conducted with the ridgeline strengthening model and the original model respectively.Simulation result indicates that the axial cushing force property of thin-walled RS square tube with the yield strength ratios of ridgeline to plate ranging from 1to 4can be predicted by using the mean crushing force formula, and the maximum deviation between theoretical result and simulation result is lower than 5.66%.Front crash simulation result comparison of the front bumper substructure before and after ridgeline strengthening shows similar plastic deformation modes and force transmission routes, and the energy absorption deviation is lower than 0.3 kJ.So, the general mild steel front bumper substructure with selective stress strengthened ridgelines can equivalently replace the corresponding higher strength steel front bumper substructure.More>

2016, 16(5): 57-65. doi: 10.19818/j.cnki.1671-1637.2016.05.007

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Locking control of hydraulic torque converter

HUI Ji-zhuang, GUO Yun-xin, ZHENG Heng-yu, ZHANG Ze-yu, HU Hao

Abstract: A type of engineering vehicle was used as research object, its characteristics of working condition were considered, and the common locking points at different throttle openings were calculated and selected based on the locking control principle.Based on throttle opening and turbine speed, brake signal, gear signal and cooling water temperature signal were considered, a multi-parameters locking control strategy was designed, and the corresponding locking flow was set up.Whole vehicle model composed of locking control model, engine model, hydraulic torque converter model, the output model of hydraulic torque converter, transmission model, and external resistance model, was built and simulated by using MATLAB/Simulink software.Simulation result shows that the locking signal responds correctly with the change of water temperature and gear signal, and the vehicle is locked at the setting locking point.The locking control model accords with the established locking control strategy, and the output model of transmission system is in line with the actual working conditions, which provides a theoretical basis for the locking control of vehicle and proposes a new scheme for improving the transmission efficiency, energy saving and emission reduction of vehicle.More>

2016, 16(5): 66-73. doi: 10.19818/j.cnki.1671-1637.2016.05.008

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Receding horizon optimization of en route flight conflict resolution strategy

TANG Xin-min, CHEN Ping, LI Bo

Abstract: Aiming at conflict resolution problem of two aircrafts on fixed airway, the static single optimal resolution strategy based on adjusting course angle and ground speed was analyzed, the uncertain factors such as speed disturbance possibly existing in aircraft flying process were considered, and a dynamic mixed optimal resolution strategy based on receding horizon optimization was proposed.The maximum likelihood estimation and Newton-Raphson iteration algorithm were used to identify wind vector.Three strategies including static optimization without disturbance, receding horizon optimization with changing ground speed of aircraft and receding horizon optimization with changing wind vector were compared.Analysis result shows that the shortest resolution time by adjusting course angle is 195 s, and the shortest resolution time by adjusting ground speed is 285 s.When the first aircraft decelerates, keeps uniform speed and accelerates, the resolution times are 240, 215 and 150 srespectively.The mean absolute errors of estimated values for wind vector's transversal and longitudinal components are 0.049 and-0.067 km ·h^-1 respectively, and the relative errors are 0.173% and-0.205% respectively.The resolution time decreases from 215 sto 160 safter wind vector is identificated.The dynamic mixed optimal resolution strategy based on wind vector identification and receding horizon optimization can timely response to the suddenly changing situation of wind vector and the ground speed of aircraft, and has good dynamic adaptability.15 figs, 27 refs.More>

2016, 16(5): 74-82. doi: 10.19818/j.cnki.1671-1637.2016.05.009

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Phase-state identification of traffic flow in terminal area incorporated with prior experience clustering

YUAN Li-gang, HU Ming-hua, ZHANG Hong-hai, MA Yong

Abstract: The traffic flow in terminal area was taken as research object, and the characteristics of traffic flow were defined and extracted based on the result of trajectory spectral clustering.The relationship of characteristics and phase-state transition law of traffic flow were analyzed to reveal three phase-states of traffic flow under observed data, including free state, steady state and congestion state, which was regarded as prior experience to further design the identification method of traffic flow situation in terminal area combining factor analysis and fuzzy clustering algorithm of genetic expectation maximization, the influence factor of traffic flow state and the recessive characteristics of traffic flow were extracted, and the observed data from typical busy terminal area were chosen to do the verification.Analysis result shows that the identification method of traffic flow situation based on objective data mining has good adaptability and accuracy, the identification numbers by the method for free state, steady state and congestion state are 6, 36 and 37 respectively, the discrimination numbers by the controller are 7, 40 and 32 respectively, the error rates are 14.3%, 10.0% and 15.6% respectively, and the identification rates are all above 84%;the extracted phase-state and time-spatial characteristic of traffic flow can be used to structure the overall operation situation in terminal area from local detail, which can provide support for the time-spatial distribution allocation of flow in terminal area and theoptimization of arrival and departure procedure.More>

2016, 16(5): 83-94. doi: 10.19818/j.cnki.1671-1637.2016.05.010

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Trailer pick-up tractor routing problem with timeliness requirement and solving

LI Hong-qi, ZHAO Wen-cong, LI Yan-ran

Abstract: Aiming at trailer pick-up tractor routing problem with timeliness requirement, fulltruck load transportation and many to many transportation demand were taken as basic characteristics, CO_2 emissions per ton-kilometer of freight transportation was taken as objective function, and a mixed integer programming model was built.A two-stage heuristic algorithm was designed based on saving algorithm and local search algorithm, and some known instances with time windows were solved.Calculation result shows that compared to the initial solutions of benchmark instances 1-12, the optimization rates of satisfactory solutions are 4.21%, 2.06%, 2.70%, 3.87%, 2.03%, 3.54%, 2.23%, 3.35%, 1.54%, 2.11%, 1.58%, and 0.81%respectively, and the average level is 2.50%, the optimum solutions are 101.22, 107.05, 106.21, 103.94, 116.23, 103.16, 102.61, 102.14, 101.05, 103.38, 103.69, and 100.54g·(t·km)-1respectively, and the average value is 104.27 g·(t·km)^-1.Obviously, the mixed integer programming model and the heuristic algorithm are feasible and effective, and the optimization of trailer pick-up tractor routing with prescription requirement can produce good energy saving and emission reduction effect.More>

2016, 16(5): 95-102. doi: 10.19818/j.cnki.1671-1637.2016.05.011

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Optimization on tractor-and-trailer transportation scheduling with uncertain empty-trailer tasks

YANG Zhen-hua, YANG Guang-min, XU Qi, GUO Shu-juan, JIN Zhi-hong

Abstract: In actual road network, the optimization model on tractor-and-trailer transportation scheduling with uncertain empty-trailer tasks was built.A two-stage heuristic algorithm was designed to solve the model.At the first stage, the transportation scheme of empty-trailer task was decided by two strategies, minimizing the transportation distance of empty-trailer and minimizing the total surplus of origin destination(OD)points for heavy-trailer tasks respectively.At the second stage, the task node surplus and the greed thought were combined to determine the execution sequence of all tasks.Numerical examples were used to analyze the performance of the algorithm.Analysis result shows that empty-trailer transportation cost and total cost are 325.5 and 1 010.5 yuan respectively, which respectively save by 10.44% and 3.62% compared to the original scheme, and less tractors are used.Based on the numerical example of tractor-and-trailer transportation among cities in Liaoning Province, the optimal values under two strategies, minimizing the transportation distance of empty-trailer and minimizing the total surplus of ODpoints for heavy-trailer tasks are 2 561.3 and 2 464.6 yuan respectively, average solving times are21.5 and 27.3 srespectively, and the results under the second strategy have good stability.The total costs computed by using simulated annealing algorithm are all above 3 100 yuan, and the solving times are all above 80 s.So, the algorithm in this paper has higher precision and efficiency, and the strategy of minimizing total surplus of OD points for heavy-trailer tasks has obvious advantages on tractor-and-trailer transportation scheduling problem with uncertain empty-trailer tasks.More>

2016, 16(5): 103-111. doi: 10.19818/j.cnki.1671-1637.2016.05.012

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Arterial coordination control optimization and application

QU Da-yi, WAN Meng-fei, WANG Zi-lin, XU Xiang-hua, WANG Jin-zhan

Abstract: The internal mechanism of arterial coordination control was analyzed based on the arrival characteristics of traffic flow at adjacent signal intersections.According to the queue state at downstream intersection, considering the constraint condition that signal state was green light when head and tail vehicles arrived, the phase offset models were proposed under three kinds of queue states including no queue, first queue and second queue.The quantitative relationship among phase offset, queue length, green time and cycle were researched.Given the relevance among the arterial intersections and the relationship between traffic demand and supply, the optimization strategy for arterial cycle, phase sequence and green ratio was proposed.Thirteen signal intersections along Binhai Road in Qingdao were selected to do case analysis.Calculation result shows that after the coordination control scheme of bidirectional green wave is used, the total travel time from east to west on Binhai Road decreases by 27.5% from 779 sto 564 sand the total stopping number of vehicle decreases from 6 to 2.The total travel time from west to east decreases by 26.5% from 806 sto 592 sand the total stopping number of vehicle decreases from 5 to 2.The phase offset model and its optimization strategy have remarkable optimization effect on the travel time and stopping number of vehicle, and this model has feasibility and practicability.More>

2016, 16(5): 112-121. doi: 10.19818/j.cnki.1671-1637.2016.05.013

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Traffic sign recognition method based on graphical model and convolutional neural network

LIU Zhan-wen, ZHAO Xiang-mo, LI Qiang, SHEN Chao, WANG Jiao-jiao

Abstract: In order to improve the recognition robustness of traffic sign, a recognition method of traffic sign based on graphical model and convolutional neural network(CNN)was proposed, and aapplication-oriented recognition system of traffic sign based on the regions with convolutional neural network(R-CNN)was set up.A graphical model based on UCM superpixel region was constructed, the multi-scales information from bottom to up was used efficiently, and a hierarchical saliency detection method based on graphical model was proposed to extract the interest regions of traffic sign.The candidate interest regions were processed for the feature extraction and classification of traffic sign with CNN.Detecting result indicates that aiming at the speed-limited signs, the graphical model based on UCM superpixel can get more larger-scale construction information of upper saliency map contrasting to the graphical model based on simple linear iterative cluster(SLIC)superpixel.Because the hierarchical saliency detection model based on the prior location restriction and the local properties combines the detail information of localregions and the constructional information of whole image, the detected results are more precise, and the detected targets are more complete and homogeneous.The detecting precision of detection model is 0.65, the recall ratio is 0.8, Findex is 0.73, and the indexes are higher than the indexes of other saliency detection methods based on superpixel.The CNN pre-training strategy for the specific detection task expends the data base of German traffic sign recognition benchmark(GTSRB), and fully uses the learning skills of CNN to learn the local fine detail features of object, so the recognition precision of CNN rises, and the recognition rate of CNN is 98.85% beyond the rate of SVM with 95.73%.More>

2016, 16(5): 122-131. doi: 10.19818/j.cnki.1671-1637.2016.05.014

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Application of BDS in western low-density railway lines

SHANGGUAN Wei, YUAN Zhong-yang, CAI Bo-gen, WANG Jian, LIU Jiang

Abstract: Considering the application requirements of low-density, low-cost and high-reliability of western railway lines, the integrated positioning technology of Beidou satellite navigation system and the inertial navigation system was studied, and the requirement of continuous and seamless positioning of train aimed at western low-density railway lines could be satisfied based on the map matching technology.When train passed through the tunnel and the mountainous area along railway lines, the Beidou satellite navigation system signal would failed due to obstacle.The short-term parameters could be derived and calculated by using the inertial navigation system constructed with accelerometer and gyroscope, train information of attitude, speed and position could be provided, which could solve the positioning problem of train because satellite signal failed in a short time.The map matching technology on the straight line and switch section ofrailway was studied, and the test was carried out based on the track map database.The Beidou satellite navigation positioning system of train aimed at western low-density railway lines was designed and established.Under the conditions of single-point static positioning in the laboratory and continuous dynamic positioning in the Qinghai-Tibet Railway Lines, the positioning functions of the system were tested.Test result shows that the average positioning error of train is 0.558 m under single-point static positioning condition, the average positioning error of train is 0.258 m under dynamic positioning condition, and the matching accuracy rate of train running trajectory point is 98.6% combining with the map matching technology based on track map database, so the system positioning errors can meet the overall positioning requirements of western low-density railway lines.More>

2016, 16(5): 132-141. doi: 10.19818/j.cnki.1671-1637.2016.05.015

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Discriminating method of abnormal dynamic information in AIS messages

LIU Xing-long, CHU Xiu-min, MA Feng, LEI Jin-yu

Abstract: Aiming at the abnormal dynamic information in ship automatic identification system(AIS)messages, a recognition approach based on probabilistic inference with four steps including prior knowledge extraction, evidence modeling, evidence combination and weight coefficient optimization was proposed.Likelihood modeling approach was used to transform artificially identified velocity, course angle and track position information included in AIS data to evidence reliability between 0 and 1 that was composed by evidential reasoning(ER)rule.The verified AIS data was regarded as the input, and nonlinear optimization approach was used to modify the weight coefficient of evidence.The AIS data of ferry in Wuhan Tianxingzhou Bridge waters and the cargo ships in Wuqiao waters were used to carry out verification test.Test result shows that the recognition accuracies of correct data, incorrect data and total data for ferry in WuhanTianxingzhou Bridge waters under optimized weight coefficients are 91.67%, 97.62% and 92.63% respectively.When the minimum total deviation is goal, the recognition accuracies of correct data, incorrect data and total data for cargo ships in Wuqiao waters are 91.79%, 89.87% and 91.65% respectively.When the minimum deviation of correct data is goal, the recognition accuracies of correct data, incorrect data and total data for cargo ships in Wuqiao waters are 93.18%, 49.95% and 90.03% respectively.Obviously, the discriminating method of AIS dynamic information based on ER rule can flexibly adjust the weight coefficient of evidence with different optimized goals, and has the accuracy close to the artificial level.More>

2016, 16(5): 142-150. doi: 10.19818/j.cnki.1671-1637.2016.05.016

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Optimization model signal priority time threshold of tram

ZHOU Yang-fan, JIA Shun-ping, CHEN Shao-kuan, WEI Wei

Abstract: Vehicle delay and intersection saturation were taken as constraint conditions, early green and extended green priority strategies were used, and the model of solving signal priority time threshold of tram was built.The influence of tram length was considered, and the model was verified through real case.Analysis result shows that the priority time thresholds under early green strategy are 0-13 s, and the priority time thresholds under extended green strategy are 5-11 s.When travelers are regarded as research units, different bus numbers under non-priority phase correspond to different overall benefit curves.When vehicles are regarded as research units, different bus numbers under non-priority phase correspond to only one overall benefit curve.The critical value of bus number under non-priority phase is 16 veh, the critical value of vehicle arrival rate under non-priority phase is 0.115pcu·s^-1, and critical value of red time is 101 s.When they exceed critical values, it is not suitable to set signal priority for tram.The optimization model of signal priority time threshold of tram in this paper provides basis for giving signal priority of tram within reasonable range.More>

2016, 16(5): 151-158. doi: 10.19818/j.cnki.1671-1637.2016.05.017

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