Showing papers in "Journal of Traffic and Transportation Engineering in 2010"

Relationship between fatigue driving and traffic accident

Abstract: Based on the statistics of road traffic accidents at home and abroad, the driver characteristics in fatigue driving, the time period distribution of accidents, and the main reasons of highway accidents were analyzed respectively. The effect of fatigue driving on operating actions and the reason of driver fatigue were studied, and the preventive measures of fatigue driving were put forward. Analysis result shows that male drivers under 30 years of age, the peoples with less than 3 years of driving ages and the peoples with about 10 years of driving ages are the colony who have more fatigue driving accidents than others. Most fatigue driving accidents happen approximately at 2:00 to 6:00 and 15:00 to 16:00, and the accident scales caused by fatigue driving on expressway are more higher than that on ordinary road. The causes of fatigue include prolonged driving, lack of sleep, circadian rhythms and driver factors. In order to prevent fatigue and reduce fatigue driving accidents, drivers are suggested to have sufficient sleep, a short rest, reasonable arrangements for travel time, and use fatigue warning devices.

Determined method of subway footway width based on queuing theory

Abstract: Subway footway and passenger flux were described as a queuing system at rush hours,a queuing optimization model was built based on the analysis of parameter characteristics,and a new approach for determining subway footway width was developed by combining the level of service for passengers with the calculation of subway footway capacity.A simulation model was proposed to testify the theoretical model above,which was capable of simulating the queuing system with any arrival process and any distribution of service time.Comparison result shows that the results of queuing optimization model and stochastic simulation at the lowest level of service are both close to the values of existing design norm,but with the improvement of service level,the values calculated by the former two methods show a remarkable trend of simultaneous growth,while those derived from the existing design norm show a level trend.2 tabs,3 figs,10 refs.

Automotive ABS control strategy based on logic threshold

Abstract: In order to solve the impact of the estimated accuracy of automotive reference speed on logic threshold control method,automotive reference speed was estimated by using correctional peak-to-peak connection method,and an automotive ABS control strategy was put forward.In the strategy,automotive slip ratio was main control threshold and automotive acceleration was secondary control threshold.A control test was carried out on the road with high attachment coefficient.Test result shows that at 45 km·h-1,the curves of automotive reference speed and real speed match,the maximal error is 6.4%,and the average error is less than 1.6%.Automotive braking time is 3.2 s,the braking distance is 15 m,and the average deceleration is 3.9 m·s-2.Obviously,the control effect is good and the control strategy is credible.2 tabs,7 figs,11 refs.

Stability analysis of rock slope based on cusp catastrophe theory

Abstract: A mechanical model for the assessment of rock slope stability was built,the criterions of the mechanical conditions resulting in the failure and instability of rock slope were inferred,the stability of rock slope was analyzed by using cusp catastrophe theory and limit equilibrium stability method applied in rigid bodies,and the latter deficiency was studied.With rigid limit equilibrium method,the stability coefficient of rock slope is 0.989,and is less than 1,which means that the slope is unstable.With cusp catastrophe theory,the rigidity ratio of the slope is 1.120,and is greater than 0.806 that is the reciprocal of water softening ratio,which means that the slope is stable.In fact,the slope is stable in excavation process,so cusp catastrophe theory may be used to analyze the stability of rock slope with complex factors.2 figs,13 refs.

Route planning of regional emergency evacuation based on lane modeling

Abstract: In order to effectively solve the potential delay during emergency evacuation routes,a lane-based network flow model was presented,its objective was the minimum of whole evacuation cost,and its constraint conditions were eliminating crossing-conflicts,reducing confluence,flow conservation and non-negative,restricting the traffic capacities of nodes and arcs.The expansion network flow model based on lane level and the traditional node-arc network model based on road level were solved by adopting Lingo software respectively,and a network including four intersections was analyzed as an example.Analysis result indicates that compared to the traditional network model,the travel cost saves four hours per vehicle,and reduces by 25% through the lane-based extension network flow model,so the model can minimize evacuation cost,reduce delay caused by merging and crossing,and improve evacuation efficiency.2 tabs,6 figs,12 refs.

Vibration test method of semi-rigid base course material

Abstract: Based on simulating the on-the-spot rolling working condition and impact of semi-rigid base course to maximal extent,the dry density and gradation of semi-rigid base course material were tested,the influence of vibration parameters on the compacting effect of semi-rigid base course material was studied,and a vibration test method of semi-rigid base course material was put forward.It is pointed that the optimum vibration parameters of vibration compaction test machine are vibration frequency at 30 Hz,excitation force at 7.6 kN,nominal vibration amplitude at 1.2 mm and vibrator mass at 300 kg,and the maximum dry density by 100 s vibration compaction is equal to the on-the-spot one.On the basis,the average accuracy of the maximum dry density and the average unconfined compressive strength by the method are 100.0% and 112.6% respectively,and they are 96.9% and 42.9% respectively by standard heavy compaction test and static compaction test.The result indicates that real base structure can be simulated accurately by the method,and the specimens produced by the method can represent the component structure and performance of on-site semi-rigid base.6 tabs,5 figs,16 refs.

Estimating method of pollution emissions for scheduled flight in different phases

Abstract: ICAO standard emission model was analyzed.The equations of parameters,such as flight time,thrust,fuel flow and so on,were induced.Flight time and fuel flow could be replaced by the equations in the model.The influence of atmosphere and flight parameters was considered,the calibrated emission index models of various pollutes were introduced,and the emission parameters in different flight phases were calculated.As the flight example of B737-800 from Xi'an to Yantai,the pollution emissions were calculated by Delphi on VEATE,and the variation rules of pollution emissions were analyzed.The result shows that the emissions of CO2 and NOx mainly appear in cruise phase,and the emissions of CO and HC occur in taxiing phase.The emissions of the four pollutes above are CO2,NOx,CO and HC in the decreasing sequence.The absolute errors between the calculation values and the reference values of ICAO are less than 1%.5 tabs,15 refs.

Airport delay performance evaluation based on fuzzy linear regression model

Abstract: In order to effectively evaluate the delay performance of airport,taking into account that the weather and traffic variable values were usually subject to some uncertainty factors,the features of traffic demand and weather were used to develop a fuzzy linear regression model for airport arrival delay,and the estimated delay was computedThe continuous baseline to measure operational airport delay performance was obtained by comparing estimated delay with actual delayThe delay performance could be evaluated based on the delay baselineAnalysis result indicates that the features of traffic demand and weather have a strong linear relationship with airport arrival delay,which can be fitted with the modelThe delay performance baseline takes into account the impact of airport weather and traffic demand on the delay,and divides the delay into low,medium and high levels,and the delays of different days can be compared and evaluated1 tab,2 figs,21 refs

Flexural behavior experiment of reinforced concrete T-beams with steel plate-concrete composite strengthening

Abstract: The flexural behaviors and failure modes of four reinforced concrete T-beams with steel plate-concrete composite strengthening were investigated.The major design parameters included damage level and bar-planted space.The loads,deflections,strains,cracks of test T-beams,the slippages between new and existing concretes,and the slippages between steel plates and new concretes were respectively measured by using load,deformation sensors and strain gauges.The ultimate bending capacities of test T-beams were simulated by using finite element software ANSYS,and were analyzed by using plastic method.The simulation values,theoretical calculation values and test values were compared.Comparison result shows that the ultimate bending capacities of the T-beams increase by two times.The influence degrees of damage levels and bar-planted spaces on the ultimate bending capacities are about 4%.The longitudinal slippages between the original and new concretes increase with the increments of bar-planted spaces.The maximal absolute differences among the simulation values,theoretical calculation values and test values are 9%,so steel plate-concrete composite strengthening method is feasible.5 tabs,17 figs,14 refs.

Relationship between characteristic of void and road performance of porous asphalt mixture

Abstract: Three Marshall specimens of OGFC-13 with different gradations were selected,and their internal void distributions were obtained by using X-CT technique and digital graphic processing technique.The fractal characteristics of voids were computed by fractal theory,and the relationship between the void characteristics and the road performances for porous asphalt mixtures were analyzed.It is indicated that the split strength of porous asphalt mixture decreases with the increase of porosity,but increases with the increase of the fractal dimension of void profile.The permeation property increases with the increase of porosity,but decreases with the increase of the fractal dimension of void profile.The fractal dimension can explain the reason of the road performance difference for the mixtures with same porosity,so the fractal dimension may be adopted to analyze the void distribution and the changing law of road performance for porous asphalt mixture.4 tabs,6 figs,18 refs.

Characteristic analysis of basic unit and complex network for urban rail transit

Abstract: The characteristics of urban rail network were comprehensively studied from part and overall perspectives.From part perspective,the 2-line,3-line and 4-line basic units of urban rail transit network were analyzed.Indicators such as transfer times,coverage intensity of attraction zone and load of transfer station were proposed to evaluate each basic unit.From overall perspective,complex network theory was used,and in topological Space P,indicators such as the degree,clustering coefficient of node and average path length were proposed to characterize overall network,and network characteristics were understood from topological network.Analysis result shows that the basic units of urban rail transit network are radiation,cross and ring.Triangle with ring,triangle with triangle and multiple triangles are relatively ideal complex forms.In the urban rail network of Beijing,with the increase of node degree,its probability distribution follows the trend of first increasing and then decreasing.The clustering coefficients of many stations are 1,and travels with no more than one time transfer are more than 80%,so the current rail network of Beijing is comparatively convenient.3 tabs,8 figs,10 refs.

Influence factors of bond performance between asphalt surface layer and semi-rigid base

Abstract: Referring to foreign LPDS shear test method,the influence of asphalt mixture,sticky layer material,semi-rigid base material,the interface of asphalt mixture and sticky layer material,the interface of viscous layer material and semi-rigid base on the shear strength between asphalt surface layer and semi-rigid base was studied with self-designed interior direct shear test and oblique shear test.The shear strength and the unit shear strength were the test evaluation indexes.It is shown that increasing the maximum nominal size and the compactness of asphalt mixture can improve interlayer bond strength.High strength,coarse and dense semi-rigid material can improve interlayer bond strength.Viscosity isn't main influence factor to select viscous layer materials,but the species and doses of viscous layer materials should be selected according to engineering practice test.Cleaning the surface of semi-rigid base is an important measure to improve bond interlayer's level.Prime coat should be sprinkled with 0.3~0.6 L·m-2 after the surface of semi-rigid base is cleaned.Casting single particle size,coarse specification and alkaline crushed stone above interlayer hot asphalt is easy to construct,and can improve interlayer bond strength.15 tabs,6 figs,10 refs.

Evaluation method of pavement roughness based on 5-DOF human-vehicle-road vibration model

Abstract: To evaluate the riding comfort of pavement,human-vehicle-road interaction was analyzed by using transfer matrix method,in which the vertical weighted root-mean-square(RMS)acceleration of passenger was adopted as the evaluation index of pavement roughness,a 5-DOF vibration model was used,and the coupled interaction between vehicle and road was consideredThe effects of running speed,rotary inertia of vehicle body,spring constant and damping constant of seat,and spring constant of tire on RMS were discussed,an evaluation method of pavement roughness based on human-vehicle-road interaction was proposed and an example was givenThe RMS accelerations of the pavements graded A,B,C and D were 0381 2,0796 3,1232 0 and 2970 6 m·s-2 respectively,and the ratings of riding comfort of the pavements were correspondent with their subjective ratingsCompared with the existing evaluation methods of pavement roughness,the evaluation method considers the impacts of pavement types and vehicle speeds,reflects the impact of rotating of vehicle,and can evaluate the riding comfort of truck9 tabs,1 fig,20 refs

Application of formal methods in train control system

Abstract: To ensure the correctness of train control system design and development,the ways of simulation,test and formalization were compared.According to the safe critical attribute of train control system,the characters related to system safety were propounded such as real time,hybrid,distribution(concurrence) and reactivity,and the specific formal methods associated with every character were introduced in details.The analysis and classification of the methods were done based on their mathematical basis and applications,and their advantages and disadvantages were given.Analysis result indicates that every method has determinate limitations,which is determined by the essences of model checking and theory proving.It is pointed out that the presentation of new method,the expansion of existing methods and the integration of many methods will be the development trend of formalization in train control system.1 tab,10 figs,46 refs.

Influence of transition curves on dynamics performance of railway vehicle

Abstract: The action forces of vehicle on transition curves were analyzed.The calculated dynamics performances of heavy haul wagon with 25 t axle load were analyzed by using dynamics simulation software SIMPACK while passing through cubic parabola type,4-3-4 type and quintic type transition curves.The calculated result was compared with the theoretical analysis one.The result indicates that the types of transition curves have great effect on the dynamics performance of vehicle,especially at connection point.Compared with 4-3-4 type and quintic type,the dynamic performance of vehicle at connection point is worse while running on quintic type transition curve,the differences of carbody vertical accelerations reach 83%,and the differences of other indexes are about 10%.The difference of carbody vertical accelerations between 4-3-4 type and quintic type is 63%,and the differences of other indexes are less than 2%.4-3-4 type and quintic type transition curves will have more advantages if the curves are prolonged.7 figs,11 refs.

Risk assessment and control measures of collapse for tunnel construction

Abstract: In order to prevent tunnel collapse and optimize tunnel design before tunnel construction,the collapse risk of Wolonggang Tunnel was taken as research object,the safety of tunnel primary shoring was analyzed,the risk factors of tunnel collapse were cleared,risk sources were identified combined with tunnel geology conditions,and analytic hierarchy process was used to rank the importantces of risk resources.The probability grades and risk loss grades were confirmed through expert investigation,and the grades of collapse risk were given by using risk matrix technique.Analysis result indicates that tunnel collapse inducements include the prompt closing of primary shoring,the removing occasion of temporary timbering,the close following of secondary lining and blasting concussion.The collapse risk grade of Wolonggang Tunnel is grade Ⅲ and is higher.6 tabs,5 figs,9 refs.

Braking stability of tractor-semitrailer running on curve

Abstract: In order to study the effect of braking condition on the stability of tractor-semitrailer running on curve,a whole vehicle model of tractor-semitrailer with 21 degrees of freedom was established by using dynamics theory and virtual prototype simulation software ADAMS.The change relations of folding angle,lateral acceleration,yaw angle velocity,vehicle speed,wheel speed and tire side-slip angle with time were analyzed when tractor-semitrailer ran on curve under the ultimate condition.Through the whole vehicle test of stable steering and step,the simulation accuracy of the model was verified.Simulation result shows that when tractor-semitrailer brakes after 3 s of turning,in 3 s,tractor's lateral acceleration becomes 0,yaw angle velocity reaches extreme value 33 rad·s-1,then decreases rapidly.While trailer's lateral acceleration reaches extreme value 4 m·s-2,and yaw angle velocity gradually decreases to 0.In the braking process on curve,tractor's rear axle first locks and slips,thus the folding phenomenon of tractor-semitrailer probably happens,which leads to the reduction of braking stability.1 tab,14 figs,11 refs.

Operating speed models for trucks at expressway tunnel sections

Abstract: In order to identify the characteristic points and operating speeds for trucks at expressway tunnel sections,the operating speed characteristics at tunnel sections were analyzed.According to car following tests,the driving behaviors and speed changes of trucks in varied length tunnels were studied,and the observation points at tunnel sections were identified.After speed observation,the characteristic points at tunnel sections were verified,the operating speed models for the characteristic points were achieved,and the validities of the models were verified.Analysis result shows that middle tunnel and short tunnel have little impacts on truck speed.200 m before tunnel entrance,entrance point and 100 m after exit are determined as three characteristic points of operating speed for long tunnel,the relative errors of the models are within 10%,so the models are valid.3 tabs,6 figs,9 refs.

Traffic incident acoustic recognition method based on wavelet decomposition and support vector machine

Abstract: The existing automatic detection and recognition methods of traffic incidents were analyzed,a recognition method with vehicle acoustic signals was proposed based on wavelet decomposition(WD) and support vector machine(SVM).Vehicle acoustic signals were decomposed with WD,the powers in different frequencies were regarded as different incident eigenvectors,and the traffic incident classifier composed of multiple SVMs was trained.The acoustic signals of normal driving,braking and crash incidents were recognized.Test result shows that various traffic incidents can be recognized with vehicle acoustic signals,the recognition rate reaches 95%,so the proposed method is feasible.1 tab,3 figs,16 refs.

Dynamic hydroplaning analysis of car tire

Abstract: The dynamic hydroplaning of car tire was studied by the theory of elastohydrodynamic lubrication.The system of elastohydrodynamic lubrication was made of tire,water on pavement and pavement.The coordinate system was set up on tire,so tire was relatively immobile,and water film was relatively mobile.To control the hydroplaning,the equations of Reynolds,thickness of water and its distortion were derived.The equations were solved by using complex direct iteration algorithm and corresponding program.Computation result indicates that the thickness of water film on pavement that can lead to the hydroplaning becomes lessening with speed increase.The hydroplaning will happen when the speed of car is 120 km·h-1 and the thickness of water film on pavement is 2 mm.2 tabs,2 figs,10 refs.

Selection model of trip modes for rural population

Abstract: Referring to the 1 249 survey data of rural population in 12 provinces of China,the influence factors of trip selection modes were analyzed.Based on the theory of disaggregate discrete choice and its modelling method,6 daily trip modes including walk,bicycle,motorcycle,agricultural truck,bus and private car were selected as the alternatives of trip modes,the characteristic variables affecting mode choice and the method getting their values were determined,and a multinomial logit(MNL)model was developed.Another 400 trip data of rural population were selected to testify the model' s validity.The result shows that the maximal absolute error between statistical data and computational values by MNL is 4.0%,so MNL has high accuracy.10 tabs,1 fig,12 refs.

Simulation and experiment of crashworthiness for combined bridge guardrail

Abstract: To improve large bridge traffic safety quality,the basic structure of a combined bridge guardrail was identified by theoretical calculations and type investigation.A number of guardrail structure optimization designs were conducted by using computer simulation based on finite element theory,and the crashworthiness of optimized guardrail was validated by full-scale vehicle crash test.Analysis result shows that the guardrail structure can effectively protect errant vehicle,and its crashworthiness can reach more than 420 kJ,which agrees with SA degree of relevant standard in China.The experiment also validates the validity and reliability of data extracted from computer simulation.2 tabs,14 figs,11 refs.

CKF-based robust filtering algorithm for GNSS/INS integrated train positioning

Abstract: Based on the fusion estimation problems of nonlinearity and robustness in integrated train positioning,the principle and architecture of global navigation satellite system/inertial navigation system(GNSS/INS)integrated train positioning system were introduced,the scheme of CKF nonlinear filter approach was given,and a novel CKF-based robust filtering algorithm was presented by applying H∞ robust filter theory to standard CKF frameThe autonomous filter state monitoring was discussed for the proposed algorithmThe filter convergence criterion and the robustness criterion of error's H∞ norm bound were analyzed,and field tests in Qinghai-Tibet Railway were illustratedAnalysis result shows that under field test condition,the average estimation error of the proposed algorithm decreases by 713% and 485% respectively in comparison with standard UKF and CKFThe root mean square of estimation error increases by 856% with constraint level from 315 to 1 3150,so the estimation precision changes mildly,and the algorithm is effective1 tab,7 figs,12 refs

Simulation of human vibration characteristics based on 9-DOF riding dynamics model

Abstract: To predict the human vibration response characteristics and riding comfort of human-vehicle system efficiently,a 9-DOF riding dynamics model of automobile was established according to human-vehicle-road interaction and multi-body dynamics principle.The dynamics equations of the model were derived by using Lagrange Principle.A time domain model of random road excitation was established according to random road excitation and the change of vehicle speed.A human-vehicle-road system simulation model was established by using MATLAB/Simulink,and the simulation and analysis of human vibration response in a light vehicle on different roads and at different speeds were carried out.Simulation result shows that the amplitude of human acceleration response significantly increases with the drop of road level at the same speed.On random road,the energy of human vibration caused by random road excition concentrates in low frequency,the first order resonance frequency appears around 5 Hz,and the second order resonance frequency occurs around 10 Hz,which is consistent with many experimental results.Therefore,the 9-DOF dynamics model and the simulation model are reliable to quickly compute the vibration characteristics of human and riding comfort under dynamic environment.4 tabs,6 figs,11 refs.

Multilevel decision method of ship's tropical cyclone avoidance route using multisource track forecast

Abstract: In order to reduce the unsafe affection on ship's tropical cyclone(TC)avoidance caused by the errors of TC track forecasts,the present situations of techniques used in ship's TC avoidance and TC track forecast were introduced,and the purport using multisource track forecast was analyzed.In the basis of introducing the application integrating multisource prediction results from observatories,a specific method using the technique of multisource data fusion and a multilevel decision diagram for ship's avoiding TC were put forward.Study result shows that TC avoidance route decided by using multisource forecast results and multilevel decision will enable decision makers to consider all the results from different observatories and more possible TC tracks,so as to reduce possible danger and loss farthest,and ensure the safeties of ships and mariners.1 tab,7 figs,8 refs.

Signal timing optimization at isolated intersections under random condition

Abstract: The stochastic characteristic of traffic flow was analyzed at isolated intersection, the deviation of queue length of phase vehicles correlating to the expected queue length was studied, the weights of all phases were considered, and an optimization model of signal timing was proposed. The quantitative relationships among phase clearance reliability(PCR), signal cycle and green time were determined, a deterministic transformation was achieved for the model, and a simulation example of two-phase signalized intersection was analyzed by using the model. The result indicates that when the variance of arrival rate increases from 0 to 350 pcu · s-1, the cycle length increases from 50 s to 232 s, and the phase with the larger variance of arrival rate needs much green time. When the queue length increases from 4 pcu to 30 pcu, the phase clearance reliability only increases from 0.712 to 0.884. The random variation of arrival rate has an obvious effect on traffic signal setting, and the model is correct.

Vibration characteristic of coupled system for straddle type monorail beam and train

Abstract: Each car of monorail train was idealized as a dynamic system with 15 degrees of freedom and its differential equations were derived by using Lagrange formulationTrack beam was idealized as Euler beamThe governing equations of motion for the coupled system of straddle type monorail beam and train were derived based on the energy method and the concert conditions of the displacements between train and monorail beamThe dynamic responses of the coupled system was studiedThe calculated result of dynamic response of monorail beam was compared with the test data at different speedsThe result shows that the effect of train speed on the deflections of beam are less than the effect on the accelerationThe acceleration increases with the increase of train speed and reaches the highest value at 40～50 km·h-1,then decreases with the increase of train speedTire model and the beam's surface roughness power spectral density function have greater effect on the calculated result of the lateral responses,and make computation error increase3 tabs,13 figs,11 refs

Simulation model and algorithm of multi-runway airport gate assignment

Abstract: Based on the traditional ideas of taxiway routing and gate waiting,a simulation model was proposed for multi-runway airport gate assignment problem.With security constraints,the model minimized total taxiing time to find out optimal assignment.On the basis of multi-runway airport informations such as ground network data,operating mode and flight schedules,a gate assignment simulation algorithm was designed and applied to real-time surface operations.Simulation result shows that compared with random assignment algorithm,the ground capacity increases by 4.6%,the times of conflict detection and resolution decrease by 10.7%,and the maximal delay reduces by 34.8%.So the efficiency of airport surface traffic is improved,and the proposed algorithm is feasible.3 tabs,4 figs,15 refs.

Mechanical responses of thin-layer asphalt concrete utilized in bridge deck pavement

Abstract: Thin-layer asphalt concrete was paved on cement concrete bridge,finite element analysis software ABAQUS was utilized to build the 3D models of box girder bridge and flanged girder bridge respectively,and the mechanical responses of pavementes with different thicknesses under traffic and thermal loads were analyzed.In addition,the effect of pavement gravity on bridge structure was studied.The result indicates that the maximum vertical shear stresses in box girder bridge and flanged girder bridge increase by about 72% and 40% respectively under vehicle load when pavement thickness increases from 4 cm to 12 cm.Thus,the possibility of the rutting occurrence decreases because of the application of thin-layer pavement.The influence of pavement thickness on the tensile stress is not obvious under thermal load,and each mechanical index is at the similar level.Under the gravity of pavement,the maximum Mises stress and principle tensile stress in box girder bridge respectively decrease by 19.62% and 17.70% by decreasing pavement thickness from 12 cm to 4 cm.At the same condition,the stress levels in flanged girder bridge respectively decrease by 13.79% and 10.16%,and the stress distribution in bridge structure is meliorated.Therefore,thin-layer asphalt concrete is feasible to be utilized in bridge deck pavement when environment condition and material performance are considered in actual engineering.2 tabs,13 figs,15 refs.

Calculating methods of stress for cement concrete pavement slab under plane loads

Abstract: With elastic base theory,the main influence factors of stress for pavement slab under plane loads were analyzed,the calculating formula form of stress was deduced by modifying the stress formula of highway pavement under standard axis load.Pavement's structural parameters were organized by orthogonal design method,and the stresses under different combinations of plane loads and pavement structures were calculated by FEM.The stresses and parameters were analyzed by nonlinear regression method,and the calculating formulae of stress under single wheel plane load were got.By introducing the modifying coefficient of load radius,the calculating formulae of stress under dual-wheel and dual-wheel-dual-axes plane loads were deduced by nonlinear regression method.The calculating formulae of stress under multi-wheel-multi-axes loads were deduced by combined load theory.Error analysis result indicates that the relative errors between the calculating results by nonlinear regression method and FEM are less than 2%,so the stress formulae have high precision.8 tabs,11 figs,11 refs.