| With the rapid development of China’s transport construction and road transportationindustry, the focus of contribution began to be shifted from the plains to the mountains and theproportion of truck traffic increased gradually, which led to the phenomeonon that trafficsafety problem of highway in mountains became more and more serious. Therefore,in-depth study on operating characteristics of trucks with heavy loads in a continuouslongitudinal sections, consideration and evaluation of sections with potential security risks,and the establishment of a continuous longitudinal sections security system, are not only basictopics on operational safety issues of highway in mountains, but also the urgent need toachieve sustainable development of road transport science.Based on analysis of research status from domestic and foreign, a clear meaning ofcontinuous longitudinal section on expressway was given, and ideal slope length ofcontinuous uphill based on operating speed was also studied. Survey sections, observationsites, dominant model and survey period were chosen in the survey program of traffic safetyof continuous longitudinal sections on expressway, trucks with50t load and Auman six-axiswere selected as text models, and measured survey of operating speed and brake drumtemperature were launched.Through the analysis of the mechanisms of trafic accidents on continuous downhillsections on expressway, basic models such as the operating speed prediction model and thebrake drum temperature prediction model were determined. Taking the operating speed oftrucks with six-axis as the dependent variable, and the slope length l and averagelongitudinal slope i of continuous downhill sections as independent variables, two kinds ofoperating speed prediction models under the condition of i≤2%and i＞2%were builtrespectively. Goodness of fit test and regression test of significance were used to check thedistribution of the residuals, which showed that the result met the requirements of normalityassumption. Further validation with measured datas was also conducted to verify the accuracyand feasibility of the model.According to the law of conservation of energy, through the calculation of the energyconversion equation of trucks on continuous downhill sections, independent variables factorssuch as slope and slope length were introduced, relational model of slope, slope length andbrake drum temperature was established. Based on the measured temperature data taken fromcontinuous downhill section K346+548~K334+637on a expressway In Inner Mongolia, thetheory temperature value of the predictive model were analysed by comparison. By fitting thedistribution of relationship between brake drum temperature predictive value and measuredvalue, revised brake hub temperature prediction model on continuous downhill sections wasestablished.Based on stress analysis of trucks, considering the equation of truck motion under thecondition of driven equilibrium, performance-based operating speed prediction model oftrucks was constructed, which gave a comprehensive reflection of combined effects of thelinear elements, road conditions, altitude and wind speed and other factors. Operating speed prediction system was also developed based on Visual Basic. Taking K000+000-K265+000onan expressway in Inner Mongoli as an example, an instance of the application of the systemwere conducted.Based on the on-spot investigation and data collection, the relationship of road alignmentsuch as horizontal alignment, vertical alignment, combining elements of curved slope andtraffic safety were analyzed, the effect of composition of traffic and the volume of traffic onthe traffic safety were discussed, and finally the main influence factors of traffic safety ofexpressway was found out. According to the characteristics of heavy vehicles, considering theuse of two-dimensional effects of operating speed and brake drum temperature,method ofrisk level classification of continuous downhill section on expressway was proposed, theclassification standard of risk level was given, and at the same time, different quantitativelengths corresponding to different risk levels were figured out.On the base of the statisticaldata of the traffic accidents of eight domestic expressways, using SPSS as the statisticalanalysis software, the correlation of hundreds of millions car accident rate per kilometer andaverage velocity、standard deviation of velocity was analyzed, and finally risk assessmentmodel of continuous uphill sections of expressway was established, specific evaluationprocess and steps were expatiated.With on-spot investigation and data collection, the applicability of traffic safetyfacilities on expressway such as the emergency lane, signs and markings, speed hump, lanerestrictions was analyzed. With the elaboration of the design principles of security ensuringscheme for continuous downhill sections of expressway was described, the two phase processof the scheme theory security analysis and implementation of construction of the continuousdownhill sections were put forward, and the setting method of induced facilities, warningfacilities, and emergency lane compulsory measures were discussed. Considering theassurance of traffic capacity and traffic safety of continuous uphill sections on expressway, asetting method of restrictive measures of continuous uphill sections was put forward, settingrequirement and geometric size of the climbing lane were also discussed combining with thecharacteristics of large vehicles.The research method combining site investigation, mathematical modeling, theoreticalanalysis and engineering verification was used in the research on the key technology of trafficsafety assurance of continuous longitudinal sections on expressway with heavy traffic, and thesafety level of continuous longitudinal sections on expressway operation was improved,which has not only an important practical influence on the construction of expressway inmountain area, but also an significant theoretical effect on the assurance of the traffic safety ofimportant project and harmonious development of traffic construction。... |
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